Network Working Group J. Tseng
Request for Comments: 4171 Riverbed Technology
Category: Standards Track K. Gibbons
McDATA Corporation
F. Travostino
Nortel
C. Du Laney
Rincon Research Corporation
J. Souza
Microsoft
September 2005
Internet Storage Name Service (iSNS)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document specifies the Internet Storage Name Service (iSNS)
protocol, used for interaction between iSNS servers and iSNS clients,
which facilitates automated discovery, management, and configuration
of iSCSI and Fibre Channel devices (using iFCP gateways) on a TCP/IP
network. iSNS provides intelligent storage discovery and management
services comparable to those found in Fibre Channel networks,
allowing a commodity IP network to function in a capacity similar to
that of a storage area network. iSNS facilitates a seamless
integration of IP and Fibre Channel networks due to its ability to
emulate Fibre Channel fabric services and to manage both iSCSI and
Fibre Channel devices. iSNS thereby provides value in any storage
network comprised of iSCSI devices, Fibre Channel devices (using iFCP
gateways), or any combination thereof.
Tseng, et al. Standards Track [Page 1]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Table of Contents
1. Introduction................................................... 6
1.1. Conventions Used in This Document........................ 6
1.2. Purpose of This Document................................. 6
2. iSNS Overview.................................................. 6
2.1. iSNS Architectural Components ........................... 7
2.1.1. iSNS Protocol (iSNSP) ........................... 7
2.1.2. iSNS Client...................................... 7
2.1.3. iSNS Server...................................... 7
2.1.4. iSNS Database ................................... 7
2.1.5. iSCSI............................................ 7
2.1.6. iFCP............................................. 7
2.2. iSNS Functional Overview................................. 8
2.2.1. Name Registration Service........................ 8
2.2.2. Discovery Domain and Login Control Service....... 8
2.2.3. State Change Notification Service............... 10
2.2.4. Open Mapping between
Fibre Channel and iSCSI Devices................. 11
2.3. iSNS Usage Model........................................ 11
2.3.1. iSCSI Initiator................................. 12
2.3.2. iSCSI Target.................................... 12
2.3.3. iSCSI-FC Gateway................................ 12
2.3.4. iFCP Gateway.................................... 12
2.3.5. Management Station.............................. 12
2.4. Administratively Controlled iSNS Settings............... 13
2.5. iSNS Server Discovery .................................. 14
2.5.1. Service Location Protocol (SLP)................. 14
2.5.2. Dynamic Host Configuration Protocol (DHCP)...... 14
2.5.3. iSNS Heartbeat Message.......................... 14
2.6. iSNS and Network Address Translation (NAT).............. 14
2.7. Transfer of iSNS Database Records between iSNS Servers.. 15
2.8. Backup iSNS Servers..................................... 17
2.9. Transport Protocols..................................... 19
2.9.1. Use of TCP for iSNS Communication............... 19
2.9.2. Use of UDP for iSNS Communication............... 20
2.9.3. iSNS Multicast and Broadcast Messages........... 20
2.10. Simple Network Management Protocol (SNMP) Requirements.. 21
3. iSNS Object Model............................................. 21
3.1. Network Entity Object .................................. 22
3.2. Portal Object .......................................... 22
3.3. Storage Node Object..................................... 22
3.4. Portal Group Object..................................... 23
3.5. FC Device Object........................................ 24
3.6. Discovery Domain Object................................. 24
3.7. Discovery Domain Set Object............................. 24
3.8. iSNS Database Model..................................... 24
4. iSNS Implementation Requirements.............................. 25
Tseng, et al. Standards Track [Page 2]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
4.1. iSCSI Requirements...................................... 25
4.1.1. Required Attributes for Support of iSCSI........ 26
4.1.2. Examples: iSCSI Object Model Diagrams........... 28
4.1.3. Required Commands and
Response Messages for Support of iSCSI.......... 30
4.2. iFCP Requirements....................................... 31
4.2.1. Required Attributes for Support of iFCP......... 31
4.2.2. Example: iFCP Object Model Diagram.............. 32
4.2.3. Required Commands and
Response Messages for Support of iFCP........... 34
5. iSNSP Message Format.......................................... 35
5.1. iSNSP PDU Header........................................ 35
5.1.1. iSNSP Version................................... 36
5.1.2. iSNSP Function ID............................... 36
5.1.3. iSNSP PDU Length................................ 36
5.1.4. iSNSP Flags..................................... 36
5.1.5. iSNSP Transaction ID............................ 36
5.1.6. iSNSP Sequence ID............................... 37
5.2. iSNSP Message Segmentation and Reassembly............... 37
5.3. iSNSP PDU Payload....................................... 37
5.3.1. Attribute Value 4-Byte Alignment................ 38
5.4. iSNSP Response Status Codes............................. 39
5.5. Authentication for iSNS Multicast and Broadcast Messages 39
5.6. Registration and Query Messages......................... 41
5.6.1. Source Attribute................................ 42
5.6.2. Message Key Attributes.......................... 42
5.6.3. Delimiter Attribute............................. 42
5.6.4. Operating Attributes............................ 43
5.6.5. Registration and Query Request Message Types ... 44
5.7. Response Messages....................................... 66
5.7.1. Status Code..................................... 66
5.7.2. Message Key Attributes in Response.............. 66
5.7.3. Delimiter Attribute in Response................. 67
5.7.4. Operating Attributes in Response................ 67
5.7.5. Registration and Query Response Message Type.... 67
5.8. Vendor-Specific Messages................................ 72
6. iSNS Attributes............................................... 73
6.1. iSNS Attribute Summary.................................. 73
6.2. Entity Identifier-Keyed Attributes...................... 76
6.2.1. Entity Identifier (EID)......................... 76
6.2.2. Entity Protocol................................. 76
6.2.3. Management IP Address .......................... 77
6.2.4. Entity Registration Timestamp .................. 77
6.2.5. Protocol Version Range.......................... 77
6.2.6. Registration Period............................. 78
6.2.7. Entity Index.................................... 78
6.2.8. Entity Next Index............................... 79
6.2.9. Entity ISAKMP Phase-1 Proposals................. 79
Tseng, et al. Standards Track [Page 3]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.2.10. Entity Certificate.............................. 79
6.3. Portal-Keyed Attributes................................. 80
6.3.1. Portal IP Address............................... 80
6.3.2. Portal TCP/UDP Port............................. 80
6.3.3. Portal Symbolic Name............................ 80
6.3.4. Entity Status Inquiry Interval.................. 81
6.3.5. ESI Port........................................ 82
6.3.6. Portal Index.................................... 82
6.3.7. SCN Port........................................ 82
6.3.8. Portal Next Index............................... 83
6.3.9. Portal Security Bitmap.......................... 83
6.3.10. Portal ISAKMP Phase-1 Proposals................. 84
6.3.11. Portal ISAKMP Phase-2 Proposals................. 84
6.3.12. Portal Certificate.............................. 84
6.4. iSCSI Node-Keyed Attributes............................. 84
6.4.1. iSCSI Name...................................... 85
6.4.2. iSCSI Node Type................................. 85
6.4.3. iSCSI Node Alias................................ 86
6.4.4. iSCSI Node SCN Bitmap .......................... 86
6.4.5. iSCSI Node Index................................ 87
6.4.6. WWNN Token...................................... 87
6.4.7. iSCSI Node Next Index .......................... 89
6.4.8. iSCSI AuthMethod................................ 89
6.5. Portal Group (PG) Object-Keyed Attributes............... 89
6.5.1. Portal Group iSCSI Name......................... 90
6.5.2. PG Portal IP Addr............................... 90
6.5.3. PG Portal TCP/UDP Port.......................... 90
6.5.4. Portal Group Tag (PGT).......................... 90
6.5.5. Portal Group Index.............................. 90
6.5.6. Portal Group Next Index......................... 91
6.6. FC Port Name-Keyed Attributes .......................... 91
6.6.1. FC Port Name (WWPN)............................. 91
6.6.2. Port ID (FC_ID)................................. 91
6.6.3. FC Port Type.................................... 92
6.6.4. Symbolic Port Name.............................. 92
6.6.5. Fabric Port Name (FWWN)......................... 92
6.6.6. Hard Address.................................... 92
6.6.7. Port IP Address................................. 92
6.6.8. Class of Service (COS).......................... 93
6.6.9. FC-4 Types...................................... 93
6.6.10. FC-4 Descriptor................................. 93
6.6.11. FC-4 Features .................................. 93
6.6.12. iFCP SCN Bitmap................................. 93
6.6.13. Port Role....................................... 94
6.6.14. Permanent Port Name (PPN)....................... 95
6.7. Node-Keyed Attributes .................................. 95
6.7.1. FC Node Name (WWNN)............................. 95
6.7.2. Symbolic Node Name.............................. 95
Tseng, et al. Standards Track [Page 4]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.7.3. Node IP Address................................. 95
6.7.4. Node IPA........................................ 96
6.7.5. Proxy iSCSI Name................................ 96
6.8. Other Attributes........................................ 96
6.8.1. FC-4 Type Code.................................. 96
6.8.2. iFCP Switch Name................................ 96
6.8.3. iFCP Transparent Mode Commands.................. 97
6.9. iSNS Server-Specific Attributes......................... 97
6.9.1. iSNS Server Vendor OUI.......................... 98
6.10. Vendor-Specific Attributes.............................. 98
6.10.1. Vendor-Specific Server Attributes............... 98
6.10.2. Vendor-Specific Entity Attributes............... 98
6.10.3. Vendor-Specific Portal Attributes............... 99
6.10.4. Vendor-Specific iSCSI Node Attributes........... 99
6.10.5. Vendor-Specific FC Port Name Attributes......... 99
6.10.6. Vendor-Specific FC Node Name Attributes......... 99
6.10.7. Vendor-Specific Discovery Domain Attributes..... 99
6.10.8. Vendor-Specific Discovery Domain Set Attributes. 99
6.10.9. Other Vendor-Specific Attributes................ 99
6.11. Discovery Domain Registration Attributes............... 100
6.11.1. DD Set ID Keyed Attributes..................... 100
6.11.2. DD ID Keyed Attributes......................... 101
7. Security Considerations...................................... 103
7.1. iSNS Security Threat Analysis ......................... 103
7.2. iSNS Security Implementation and Usage Requirements.... 104
7.3. Discovering Security Requirements of Peer Devices...... 105
7.4. Configuring Security Policies of iFCP/iSCSI Devices.... 106
7.5. Resource Issues........................................ 107
7.6. iSNS Interaction with IKE and IPSec.................... 107
8. IANA Considerations.......................................... 107
8.1. Registry of Block Storage Protocols.................... 107
8.2. Registry of Standard iSNS Attributes .................. 108
8.3. Block Structure Descriptor (BSD) Registry.............. 108
9. Normative References......................................... 109
10. Informative References....................................... 110
Appendix A: iSNS Examples........................................ 112
A.1. iSCSI Initialization Example........................... 112
A.1.1. Simple iSCSI Target Registration............... 112
A.1.2. Target Registration and DD Configuration....... 114
A.1.3. Initiator Registration and Target Discovery.... 117
Acknowledgements................................................. 121
Tseng, et al. Standards Track [Page 5]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
1. Introduction
1.1. Conventions Used in This Document
"iSNS" refers to the storage network model and associated services
covered in the text of this document.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
All frame formats are in big endian network byte order.
All unused fields and bitmaps, including those that are RESERVED,
SHOULD be set to zero when sending and ignored when receiving.
1.2. Purpose of This Document
This is a standards track document containing normative text
specifying the iSNS Protocol, used by iSCSI and iFCP devices to
communicate with the iSNS server. This document focuses on the
interaction between iSNS servers and iSNS clients; interactions among
multiple authoritative primary iSNS servers are a potential topic for
future work.
2. iSNS Overview
iSNS facilitates scalable configuration and management of iSCSI and
Fibre Channel (FCP) storage devices in an IP network by providing a
set of services comparable to that available in Fibre Channel
networks. iSNS thus allows a commodity IP network to function at a
level of intelligence comparable to a Fibre Channel fabric. iSNS
allows the administrator to go beyond a simple device-by-device
management model, where each storage device is manually and
individually configured with its own list of known initiators and
targets. Using the iSNS, each storage device subordinates its
discovery and management responsibilities to the iSNS server. The
iSNS server thereby serves as the consolidated configuration point
through which management stations can configure and manage the entire
storage network, including both iSCSI and Fibre Channel devices.
iSNS can be implemented to support iSCSI and/or iFCP protocols as
needed; an iSNS implementation MAY provide support for one or both of
these protocols as desired by the implementor. Implementation
requirements within each of these protocols are further discussed in
Section 5. Use of iSNS is OPTIONAL for iSCSI and REQUIRED for iFCP.
Tseng, et al. Standards Track [Page 6]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
2.1. iSNS Architectural Components
2.1.1. iSNS Protocol (iSNSP)
The iSNS Protocol (iSNSP) is a flexible and lightweight protocol that
specifies how iSNS clients and servers communicate. It is suitable
for various platforms, including switches and targets as well as
server hosts.
2.1.2. iSNS Client
iSNS clients initiate transactions with iSNS servers using the iSNSP.
iSNS clients are processes that are co-resident in the storage
device, and that can register device attribute information, download
information about other registered clients in a common Discovery
Domain (DD), and receive asynchronous notification of events that
occur in their DD(s). Management stations are a special type of iSNS
client that have access to all DDs stored in the iSNS.
2.1.3. iSNS Server
iSNS servers respond to iSNS protocol queries and requests, and
initiate iSNS protocol State Change Notifications. Properly
authenticated information submitted by a registration request is
stored in an iSNS database.
2.1.4. iSNS Database
The iSNS database is the information repository for the iSNS
server(s). It maintains information about iSNS client attributes. A
directory-enabled implementation of iSNS may store client attributes
in an LDAP directory infrastructure.
2.1.5. iSCSI
iSCSI (Internet SCSI) is an encapsulation of SCSI for a new
generation of storage devices interconnected with TCP/IP [iSCSI].
2.1.6. iFCP
iFCP (Internet FCP) is a gateway-to-gateway protocol designed to
interconnect existing Fibre Channel and SCSI devices using TCP/IP.
iFCP maps the existing FCP standard and associated Fibre Channel
services to TCP/IP [iFCP].
Tseng, et al. Standards Track [Page 7]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
2.2. iSNS Functional Overview
There are four main functions of the iSNS:
1) A Name Service Providing Storage Resource Discovery
2) Discovery Domain (DD) and Login Control Service
3) State Change Notification Service
4) Open Mapping of Fibre Channel and iSCSI Devices
2.2.1. Name Registration Service
The iSNS provides a registration function to allow all entities in a
storage network to register and query the iSNS database. Both
targets and initiators can register in the iSNS database, as well as
query for information about other initiators and targets. This
allows, for example, a client initiator to obtain information about
target devices from the iSNS server. This service is modeled on the
Fibre Channel Generic Services Name Server described in FC-GS-4, with
extensions, operating within the context of an IP network.
The naming registration service also provides the ability to obtain a
network-unique Domain ID for iFCP gateways when one is required.
2.2.2. Discovery Domain and Login Control Service
The Discovery Domain (DD) Service facilitates the partitioning of
Storage Nodes into more manageable groupings for administrative and
login control purposes. It allows the administrator to limit the
login process of each host to the more appropriate subset of targets
registered in the iSNS. This is particularly important for reducing
the number of unnecessary logins (iSCSI logins or Fibre Channel Port
Logins), and for limiting the amount of time that the host spends
initializing login relationships as the size of the storage network
scales up. Storage Nodes must be in at least one common enabled DD
in order to obtain information about each other. Devices can be
members of multiple DDs simultaneously.
Login Control allows targets to delegate their access
control/authorization policies to the iSNS server. This is
consistent with the goal of centralizing management of those storage
devices using the iSNS server. The target node or device downloads
the list of authorized initiators from the iSNS. Each node or device
is uniquely identified by an iSCSI Name or FC Port Name. Only
Tseng, et al. Standards Track [Page 8]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
initiators that match the required identification and authorization
provided by the iSNS will be allowed access by that target Node
during session establishment.
Placing Portals of a Network Entity into Discovery Domains allows
administrators to indicate the preferred IP Portal interface through
which storage traffic should access specific Storage Nodes of that
Network Entity. If no Portals of a Network Entity have been placed
into a DD, then queries scoped to that DD SHALL report all Portals of
that Network Entity. If one or more Portals of a Network Entity have
been placed into a DD, then queries scoped to that DD SHALL report
only those Portals that have been explicitly placed in the DD.
DDs can be managed offline through a separate management workstation
using the iSNSP or SNMP. If the target opts to use the Login Control
feature of the iSNS, the target delegates management of access
control policy (i.e., the list of initiators allowed to log in to
that target) to the management workstations that are managing the
configuration in the iSNS database.
If administratively authorized, a target can upload its own Login
Control list. This is accomplished using the DDReg message and
listing the iSCSI name of each initiator to be registered in the
target's DD.
An implementation MAY decide that newly registered devices that have
not explicitly been placed into a DD by the management station will
be placed into a "default DD" contained in a "default DDS" whose
initial DD Set Status value is "enabled". This makes them visible to
other devices in the default DD. Other implementations MAY decide
that they are registered with no DD, making them inaccessible to
source-scoped iSNSP messages.
The iSNS server uses the Source Attribute of each iSNSP message to
determine the originator of the request and to scope the operation to
a set of Discovery Domains. In addition, the Node Type (specified in
the iFCP or iSCSI Node Type bitmap field) may also be used to
determine authorization for the specified iSNS operation. For
example, only Control Nodes are authorized to create or delete
discovery domains.
Valid and active Discovery Domains (DDs) belong to at least one
active Discovery Domain Set (DDS). Discovery Domains that do not
belong to an activated DDS are not enabled. The iSNS server MUST
maintain the state of DD membership for all Storage Nodes, even for
those that have been deregistered. DD membership is persistent
regardless of whether a Storage Node is actively registered in the
iSNS database.
Tseng, et al. Standards Track [Page 9]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
2.2.3. State Change Notification Service
The State Change Notification (SCN) service allows the iSNS Server to
issue notifications about network events that affect the operational
state of Storage Nodes. The iSNS client may register for
notifications on behalf of its Storage Nodes for notification of
events detected by the iSNS Server. SCNs notify iSNS clients of
explicit or implicit changes to the iSNS database; they do not
necessarily indicate the state of connectivity to peer storage
devices in the network. The response of a storage device to receipt
of an SCN is implementation-specific; the policy for responding to
SCNs is outside of the scope of this document.
There are two types of SCN registrations: regular registrations and
management registrations. Management registrations result in
management SCNs, whereas regular registrations result in regular
SCNs. The type of registration and SCN message is indicated in the
SCN bitmap (see Sections 6.4.4 and 6.6.12).
A regular SCN registration indicates that the Discovery Domain
Service SHALL be used to control the distribution of SCN messages.
Receipt of regular SCNs is limited to the discovery domains in which
the SCN-triggering event takes place. Regular SCNs do not contain
information about discovery domains.
A management SCN registration can only by requested by Control Nodes.
Management SCNs resulting from management registrations are not bound
by the Discovery Domain service. Authorization to request management
SCN registrations may be administratively controlled.
The iSNS server SHOULD be implemented with hardware and software
resources sufficient to support the expected number of iSNS clients.
However, if resources are unexpectedly exhausted, then the iSNS
server MAY refuse SCN service by returning an SCN Registration
Rejected (Status Code 17). The rejection might occur in situations
where the network size or current number of SCN registrations has
passed an implementation-specific threshold. A client not allowed to
register for SCNs may decide to monitor its sessions with other
storage devices directly.
The specific notification mechanism by which the iSNS server learns
of the events that trigger SCNs is implementation-specific, but can
include examples such as explicit notification messages from an iSNS
client to the iSNS server, or a hardware interrupt to a switch-hosted
iSNS server as a result of link failure.
Tseng, et al. Standards Track [Page 10]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
2.2.4. Open Mapping between Fibre Channel and iSCSI Devices
The iSNS database stores naming and discovery information about both
Fibre Channel and iSCSI devices. This allows the iSNS server to
store mappings of a Fibre Channel device to a proxy iSCSI device
"image" in the IP network. Similarly, mappings of an iSCSI device to
a "proxy WWN" can be stored under the WWNN Token field for that iSCSI
device.
Furthermore, through use of iSCSI-FC gateways, Fibre Channel-aware
management stations can interact with the iSNS server to retrieve
information about Fibre Channel devices, and use this information to
manage Fibre Channel and iSCSI devices. This allows management
functions such as Discovery Domains and State Change Notifications to
be applied seamlessly to both iSCSI and Fibre Channel devices,
facilitating integration of IP networks with Fibre Channel devices
and fabrics.
Note that Fibre Channel attributes are stored as iFCP attributes, and
that the ability to store this information in the iSNS server is
useful even if the iFCP protocol is not implemented. In particular,
tag 101 can be used to store a "Proxy iSCSI Name" for Fibre Channel
devices registered in the iSNS server. This field is used to
associate the FC device with an iSCSI registration entry that is used
for the Fibre Channel device to communicate with iSCSI devices in the
IP network. Conversely, tag 37 (see Section 6.1) contains a WWNN
Token field, which can be used to store an FC Node Name (WWNN) value
used by iSCSI-FC gateways to represent an iSCSI device in the Fibre
Channel domain.
By storing the mapping between Fibre Channel and iSCSI devices in the
iSNS server, this information becomes open to any authorized iSNS
client wishing to retrieve and use this information. In many cases,
this provides advantages over storing the information internally
within an iSCSI-FC gateway, where the mapping is inaccessible to
other devices except by proprietary mechanisms.
2.3. iSNS Usage Model
The following is a high-level description of how each type of device
in a storage network can utilize iSNS. Each type of device interacts
with the iSNS server as an iSNS client and must register itself in
the iSNS database in order to access services provided by the iSNS.
Tseng, et al. Standards Track [Page 11]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
2.3.1. iSCSI Initiator
An iSCSI initiator will query the iSNS server to discover the
presence and location of iSCSI target devices. It may also request
state change notifications (SCNs) so that it can be notified of new
targets that appear on the network after the initial bootup and
discovery. SCNs can also inform the iSCSI initiator of targets that
have been removed from or no longer available in the storage network,
so that incomplete storage sessions can be gracefully terminated and
resources for non-existent targets can be reallocated.
2.3.2. iSCSI Target
An iSCSI target allows itself to be discovered by iSCSI initiators by
registering its presence in the iSNS server. It may also register
for SCNs in order to detect the addition or removal of initiators for
resource allocation purposes. The iSCSI target device may also
register for Entity Status Inquiry (ESI) messages, which allow the
iSNS to monitor the target device's availability in the storage
network.
2.3.3. iSCSI-FC Gateway
An iSCSI-FC gateway bridges devices in a Fibre Channel network to an
iSCSI/IP network. It may use the iSNS server to store FC device
attributes discovered in the FC name server, as well as mappings of
FC device identifiers to iSCSI device identifiers. iSNS has the
capability to store all attributes of both iSCSI and Fibre Channel
devices; iSCSI devices are managed through direct interaction using
iSNS, while FC devices can be indirectly managed through iSNS
interactions with the iSCSI-FC gateway. This allows both iSCSI and
Fibre Channel devices to be managed in a seamless management
framework.
2.3.4. iFCP Gateway
An iFCP gateway uses iSNS to emulate the services provided by a Fibre
Channel name server for FC devices in its gateway region. iSNS
provides basic discovery and zoning configuration information to be
enforced by the iFCP gateway. When queried, iSNS returns information
on the N_Port network address used to establish iFCP sessions between
FC devices supported by iFCP gateways.
2.3.5. Management Station
A management station uses iSNS to monitor storage devices and to
enable or disable storage sessions by configuring discovery domains.
A management station usually interacts with the iSNS server as a
Tseng, et al. Standards Track [Page 12]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Control Node endowed with access to all iSNS database records and
with special privileges to configure discovery domains. Through
manipulation of discovery domains, the management station controls
the scope of device discovery for iSNS clients querying the iSNS
server.
2.4. Administratively Controlled iSNS Settings
Some important operational settings for the iSNS server are
configured using administrative means, such as a configuration file,
a console port, an SNMP, or another implementation-specific method.
These administratively-controlled settings cannot be configured using
the iSNS Protocol, and therefore the iSNS server implementation MUST
provide for such an administrative control interface.
The following is a list of parameters that are administratively
controlled for the iSNS server. In the absence of alternative
settings provided by the administrator, the following specified
default settings MUST be used.
Setting Default Setting
------- ---------------
ESI Non-Response Threshold 3 (see 5.6.5.13)
Management SCNs (Control Nodes only) enabled (see 5.6.5.8)
Default DD/DDS disabled
DD/DDS Modification
- Control Node enabled
- iSCSI Target Node Type disabled
- iSCSI Initiator Node Type disabled
- iFCP Target Port Role disabled
- iFCP Initiator Port Role disabled
Authorized Control Nodes N/A
ESI Non-Response Threshold: determines the number of ESI messages
sent without receiving a response before the network
entity is deregistered from the iSNS database.
Management SCN for Control Node: determines whether a registered
Control Node is permitted to register to receive
Management SCNs.
Default DD/DDS: determines whether a newly registered device not
explicitly placed into a discovery domain (DD) and
discovery domain set (DDS) is placed into a default
DD/DDS.
DD/DDS Modification: determines whether the specified type of Node is
allowed to add, delete or update DDs and DDSs.
Tseng, et al. Standards Track [Page 13]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Authorized Control Nodes: a list of Nodes identified by iSCSI Name or
FC Port Name WWPN that are authorized to register as
Control Nodes.
2.5. iSNS Server Discovery
2.5.1. Service Location Protocol (SLP)
The Service Location Protocol (SLP) provides a flexible and scalable
framework for providing hosts with access to information about the
existence, location, and configuration of networked services,
including the iSNS server. SLP can be used by iSNS clients to
discover the IP address or FQDN of the iSNS server. To implement
discovery through SLP, a Service Agent (SA) should be cohosted in the
iSNS server, and a User Agent (UA) should be in each iSNS client.
Each client multicasts a discovery message requesting the IP address
of the iSNS server(s). The SA responds to this request. Optionally,
the location of the iSNS server can be stored in the SLP Directory
Agent (DA).
Note that a complete description and specification of SLP can be
found in [RFC2608], and is beyond the scope of this document. A
service template for using SLP to locate iSNS servers can be found in
[iSCSI-SLP].
2.5.2. Dynamic Host Configuration Protocol (DHCP)
The IP address of the iSNS server can be stored in a DHCP server to
be downloaded by iSNS clients using a DHCP option. The DHCP option
number to be used for distributing the iSNS server location is found
in [iSNSOption].
2.5.3. iSNS Heartbeat Message
The iSNS heartbeat message is described in Section 5.6.5.14. It
allows iSNS clients within the broadcast or multicast domain of the
iSNS server to discover the location of the active iSNS server and
any backup servers.
2.6. iSNS and Network Address Translation (NAT)
The existence of NAT will have an impact upon information retrieved
from the iSNS server. If the iSNS client exists in an addressing
domain different from that of the iSNS server, then IP address
information stored in the iSNS server may not be correct when
interpreted in the domain of the iSNS client.
Tseng, et al. Standards Track [Page 14]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
There are several possible approaches to allow operation of iSNS
within a NAT network. The first approach is to require use of the
canonical TCP port number by both targets and initiators when
addressing targets across a NAT boundary, and for the iSNS client not
to query for nominal IP addresses. Rather, the iSNS client queries
for the DNS Fully Qualified Domain Name stored in the Entity
Identifier field when seeking addressing information. Once
retrieved, the DNS name can be interpreted in each address domain and
mapped to the appropriate IP address by local DNS servers.
A second approach is to deploy a distributed network of iSNS servers.
Local iSNS servers are deployed inside and outside NAT boundaries,
with each local server storing relevant IP addresses for their
respective NAT domains. Updates among the network of decentralized,
local iSNS servers are handled using LDAP and appropriate NAT
translation rules implemented within the update mechanism in each
server.
Finally, note that it is possible for an iSNS server in the private
addressing domain behind a NAT boundary to exclusively support iSNS
clients that are operating in the global IP addressing domain. If
this is the case, the administrator only needs to ensure that the
appropriate mappings are configured on the NAT gateways to allow the
iSNS clients to initiate iSNSP sessions to the iSNS server. All
registered addresses contained in the iSNS server are thus public IP
addresses for use outside the NAT boundary. Care should be taken to
ensure that there are no iSNS clients querying the server from inside
the NAT boundary.
2.7. Transfer of iSNS Database Records between iSNS Servers
Transfer of iSNS database records between iSNS servers has important
applications, including the following:
1) An independent organization needs to transfer storage information
to a different organization. Each organization independently
maintains its own iSNS infrastructure. To facilitate discovery
of storage assets of the peer organization using IP, iSNS
database records can be transferred between authoritative iSNS
servers from each organization. This allows storage sessions to
be established directly between devices residing in each
organization's storage network infrastructure over a common IP
network.
2) Multiple iSNS servers are desired for redundancy. Backup servers
need to maintain copies of the primary server's dynamically
changing database.
Tseng, et al. Standards Track [Page 15]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
To support the above applications, information in an iSNS server can
be distributed to other iSNS servers either using the iSNS protocol,
or through out-of-band mechanisms using non-iSNS protocols. The
following examples illustrate possible methods for transferring data
records between iSNS servers. In the first example, a back-end LDAP
information base is used to support the iSNS server, and the data is
transferred using the LDAP protocol. Once the record transfer of the
remote device is completed, it becomes visible and accessible to
local devices using the local iSNS server. This allows local devices
to establish sessions with remote devices (provided that firewall
boundaries can be negotiated).
+-------------------------+ +-------------------------+
|+------+ iSNSP | | iSNSP +-----+ |
||dev A |<----->+------+ | | +------+<----->|dev C| |
|+------+ | | | | | | +-----+ |
|+------+ iSNSP |local | | | |remote| iSNSP +-----+ |
||dev B |<----->| iSNS | | | | iSNS |<----->|dev D| |
|+------+ |server| | | |server| +-----+ |
|........ +--+---+ | WAN | +---+--+ |
|.dev C'. | | Link | | |
|........ | ============= | |
| | | | | |
| +--+---+ | | +---+--+ |
| | local|<--- <--- <--- <-|remote| |
| | LDAP | | LDAP: | | LDAP | |
| +------+ Xfer "dev C"| +------+ |
+-------------------------+ +-------------------------+
Enterprise Enterprise
Network A Network B
In the above diagram, two business partners wish to share storage
"dev C". Using LDAP, the record for "dev C" can be transferred from
Network B to Network A. Once accessible to the local iSNS server in
Network A, local devices A and B can now discover and connect to "dev
C".
Tseng, et al. Standards Track [Page 16]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
+-------------------------+ +-------------------------+
|+------+ iSNSP | | iSNSP +-----+ |
||dev A |<----->+------+ | | +------+<----->|dev C| |
|+------+ | | | | | | +-----+ |
|+------+ iSNSP |local | | | |remote| iSNSP +-----+ |
||dev B |<----->| iSNS | | | | iSNS |<----->|dev D| |
|+------+ |server| | | |server| +-----+ |
|........ +------+ | WAN | +---+--+ |
|.dev C'. ^ | Link | | |
|........ | ============= v |
| | | | |SNMP |
| | | | | |
| +--+----+ | | v |
| | SNMP |<--- <--- <--- <---- |
| | Mgmt | | SNMP: Xfer "dev C" |
| |Station| | | |
| +-------+ | | |
+-------------------------+ +-------------------------+
Enterprise Enterprise
Network A Network B
The above diagram illustrates a second example of how iSNS records
can be shared. This method uses an SNMP-based management station to
retrieve (GET) the desired record for "dev C" manually, and then to
store (SET) it on the local iSNS server directly. Once the record is
transferred to the local iSNS server in Network A, "dev C" becomes
visible and accessible (provided that firewall boundaries can be
negotiated) to other devices in Network A.
Other methods, including proprietary protocols, can be used to
transfer device records between iSNS servers. Further discussion and
explanation of these methodologies is beyond the scope of this
document.
2.8. Backup iSNS Servers
This section offers a broad framework for implementation and
deployment of iSNS backup servers. Server failover and recovery are
topics of continuing research, and adequate resolution of issues such
as split brain and primary server selection is dependent on the
specific implementation requirements and deployment needs. The
failover mechanisms discussed in this document focus on the
interaction between iSNS clients and iSNS servers. Specifically,
what is covered in this document includes the following:
- iSNS client behavior and the iSNS protocol interaction between the
client and multiple iSNS servers, some of which are backup
servers.
Tseng, et al. Standards Track [Page 17]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
- Required failover behaviors of the collection of iSNS servers that
includes active and backup servers.
However, note that this document does not specify the complete
functional failover requirements of each iSNS server. In particular,
it does not specify the complete set of protocol interactions among
the iSNS servers that are required to achieve stable failover
operation in an interoperable manner.
For the purposes of this discussion, the specified backup mechanisms
pertain to interaction among different logical iSNS servers. Note
that it is possible to create multiple physical iSNS servers to form
a single logical iSNS server cluster, and thus to distribute iSNS
transaction processing among multiple physical servers. However, a
more detailed discussion of the interactions between physical servers
within a logical iSNS server cluster is beyond the scope of this
document.
Multiple logical iSNS servers can be used to provide redundancy in
the event that the active iSNS server fails or is removed from the
network. The methods described in Section 2.7 above can be used to
transfer name server records to backup iSNS servers. Each backup
server maintains a redundant copy of the name server database found
in the primary iSNS server, and can respond to iSNS protocol messages
in the same way as the active server. Each backup server SHOULD
monitor the health and status of the active iSNS server, including
checking to make sure its own database is synchronized with the
active server's database. How each backup server accomplishes this
is implementation-dependent, and may (or may not) include using the
iSNS protocol. If the iSNS protocol is used, then the backup server
MAY register itself in the active server's iSNS database as a Control
Node, allowing it to receive state-change notifications.
Generally, the administrator or some automated election process is
responsible for initial and subsequent designation of the primary
server and each backup server.
A maximum of one logical backup iSNS server SHALL exist at any
individual IP address, in order to avoid conflicts from multiple
servers listening on the same canonical iSNS TCP or UDP port number.
The iSNS heartbeat can also be used to coordinate the designation and
selection of primary and backup iSNS servers.
Each backup server MUST note its relative precedence in the active
server's list of backup servers. If its precedence is not already
known, each backup server MAY learn it from the iSNS heartbeat
message, by noting the position of its IP address in the ordered list
Tseng, et al. Standards Track [Page 18]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
of backup server IP addresses. For example, if it is the first
backup listed in the heartbeat message, then its backup precedence is
1. If it is the third backup server listed, then its backup
precedence is 3.
If a backup server establishes that it has lost connectivity to the
active server and other backup servers of higher precedence, then it
SHOULD assume that it is the active server. The method of
determining whether connectivity has been lost is implementation-
specific. One possible approach is to assume that if the backup
server does not receive iSNS heartbeat messages for a period of time,
then connectivity to the active server has been lost. Alternatively,
the backup server may establish TCP connections to the active server
and other backup servers, with loss of connectivity determined
through non-response to periodic echo or polling messages (using
iSNSP, SNMP, or other protocols).
When a backup server becomes the active server, it SHALL assume all
active server responsibilities, including (if used) transmission of
the iSNS heartbeat message. If transmitting the iSNS heartbeat, the
backup server replaces the active Server IP Address and TCP/UDP Port
entries with its own IP address and TCP/UDP Port, and begins
incrementing the counter field from the last known value from the
previously-active iSNS server. However, it MUST NOT change the
original ordered list of backup server IP Address and TCP/UDP Port
entries. If the primary backup server or other higher-precedence
backup server returns, then the existing active server is responsible
for ensuring that the new active server's database is up-to-date
before demoting itself to its original status as backup.
Since the primary and backup iSNS servers maintain a coordinated
database, no re-registration by an iSNS Client is required when a
backup server takes the active server role. Likewise, no re-
registration by an iSNS Client is required when the previous primary
server returns to the active server role.
2.9. Transport Protocols
The iSNS Protocol is transport-neutral. Query and registration
messages are transported over TCP or UDP. iSNS heartbeat messages
are transported using IP multicast or broadcast.
2.9.1. Use of TCP for iSNS Communication
It MUST be possible to use TCP for iSNS communication. The iSNS
server MUST accept TCP connections for client registrations. To
receive Entity Status Inquiry (ESI) (see Section 5.6.5.13) monitoring
the use of TCP, the client registers the Portal ESI Interval and the
Tseng, et al. Standards Track [Page 19]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
port number of the TCP port that will be used to receive ESI
messages. The iSNS server initiates the TCP connection used to
deliver the ESI message. This TCP connection does not need to be
continuously open.
To receive SCN notifications using TCP, the client registers the
iSCSI or iFCP SCN Bitmap and the port number of the TCP port in the
Portal used to receive SCNs. The iSNS server initiates the TCP
connection used to deliver the SCN message. This TCP connection does
not need to be continuously open.
It is possible for an iSNS client to use the same TCP connection for
SCN, ESI, and iSNS queries. Alternatively, separate connections may
be used.
2.9.2. Use of UDP for iSNS Communication
The iSNS server MAY accept UDP messages for client registrations.
The iSNS server MUST accept registrations from clients requesting
UDP-based ESI and SCN messages.
To receive UDP-based ESI monitoring messages, the client registers
the port number of the UDP port in at least one Portal to be used to
receive and respond to ESI messages from the iSNS server. If a
Network Entity has multiple Portals with registered ESI UDP Ports,
then ESI messages SHALL be delivered to every Portal registered to
receive such messages.
To receive UDP-based SCN notification messages, the client registers
the port number of the UDP port in at least one Portal to be used to
receive SCN messages from the iSNS server. If a Network Entity has
multiple Portals with registered SCN UDP Ports, then SCN messages
SHALL be delivered to each Portal registered to receive such
messages.
When using UDP to transport iSNS messages, each UDP datagram MUST
contain exactly one iSNS PDU (see Section 5).
2.9.3. iSNS Multicast and Broadcast Messages
iSNS multicast messages are transported using IP multicast or
broadcast. The iSNS heartbeat is the only iSNS multicast or
broadcast message. This message is originated by the iSNS server and
sent to all iSNS clients that are listening on the IP multicast
address allocated for the iSNS heartbeat.
Tseng, et al. Standards Track [Page 20]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
2.10. Simple Network Management Protocol (SNMP) Requirements
The iSNS Server may be managed via the iSNS MIB [iSNSMIB] using an
SNMP management framework [RFC3411]. For a detailed overview of the
documents that describe the current Internet-Standard Management
Framework, please refer to Section 7 of RFC 3410 [RFC3410]. The iSNS
MIB provides the ability to configure and monitor an iSNS server
without using the iSNS protocol directly. SNMP management frameworks
have several requirements for object indexing in order for objects to
be accessed or added.
SNMP uses an Object Identifier (OID) for object identification. The
size of each OID is restricted to a maximum of 128 sub-identifiers.
Both the iSCSI and iFCP protocol contain identifiers, such as the
iSCSI Name, that are greater the 128 characters in length. Using
such identifiers as an index would result in more than 128 sub-
identifiers per OID. In order to support objects that have key
identifiers whose maximum length is longer than the maximum SNMP-
supported length, the iSNS server provides secondary non-zero integer
index identifiers. These indexes SHALL be persistent for as long as
the server is active. Furthermore, index values for recently
deregistered objects SHOULD NOT be reused in the short term. Object
attributes, including indexes, are described in detail in Section 6.
For SNMP based management applications to create a new entry in a
table of objects, a valid OID must be available to specify the table
row. The iSNS server supports this by providing, for each type of
object that can be added via SNMP, an object attribute that returns
the next available non-zero integer index. This allows an SNMP
client to request an OID to be used for registering a new object in
the server. Object attributes, including next available index
attributes, are described in detail in Section 6.
3. iSNS Object Model
iSNS provides the framework for the registration, discovery, and
management of iSCSI devices and Fibre Channel-based devices (using
iFCP). This architecture framework provides elements needed to
describe various storage device objects and attributes that may exist
on an IP storage network. Objects defined in this architecture
framework include Network Entity, Portal, Storage Node, FC Device,
Discovery Domain, and Discovery Domain Set. Each of these objects is
described in greater detail in the following sections.
Tseng, et al. Standards Track [Page 21]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
3.1. Network Entity Object
The Network Entity object is a container of Storage Node objects and
Portal objects. It represents the infrastructure supporting access
to a unique set of one or more Storage Nodes. The Entity Identifier
attribute uniquely distinguishes a Network Entity, and is the key
used to register a Network Entity object in an iSNS server. All
Storage Nodes and Portals contained within a single Network Entity
object operate as a cohesive unit.
Note that it is possible for a single physical device or gateway to
be represented by more than one logical Network Entity in the iSNS
database. For example, one of the Storage Nodes on a physical device
may be accessible from only a subset of the network interfaces (i.e.,
Portals) available on that device. In this case, a logical network
entity (i.e., a "shadow entity") is created and used to contain the
Portals and Storage Nodes that can operate cooperatively. No object
(Portals, Storage Nodes, etc.) can be contained in more than one
logical Network Entity.
Similarly, it is possible for a logical Network Entity to be
supported by more than one physical device or gateway. For example,
multiple FC-iSCSI gateways may be used to bridge FC devices in a
single Fibre Channel network. Collectively, the multiple gateways
can be used to support a single logical Network Entity that is used
to contain all the devices in that Fibre Channel network.
3.2. Portal Object
The Portal object is an interface through which access to Storage
Nodes within the Network Entity can be obtained. The IP address and
TCP/UDP Port number attributes uniquely distinguish a Portal object,
and combined are the key used to register a Portal object in an iSNS
server. A Portal is contained in one and only one Network Entity,
and may be contained in one or more DDs (see Section 3.6).
3.3. Storage Node Object
The Storage Node object is the logical endpoint of an iSCSI or iFCP
session. In iFCP, the session endpoint is represented by the World
Wide Port Name (WWPN). In iSCSI, the session endpoint is represented
by the iSCSI Name of the device. For iSCSI, the iSCSI Name attribute
uniquely distinguishes a Storage Node, and is the key used to
register a Storage Node object in an iSNS Server. For iFCP, the FC
Port Name (WWPN) attribute uniquely distinguishes a Storage Node, and
is the key used to register a Storage Node object in the iSNS Server.
Storage Node is contained in only one Network Entity object and may
be contained in one or more DDs (see Section 3.6).
Tseng, et al. Standards Track [Page 22]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
3.4. Portal Group Object
The Portal Group (PG) object represents an association between a
Portal and an iSCSI Node. Each Portal and iSCSI Storage Node
registered in an Entity can be associated using a Portal Group (PG)
object. The PG Tag (PGT), if non-NULL, indicates that the associated
Portal provides access to the associated iSCSI Storage Node in the
Entity. All Portals that have the same PGT value for a specific
iSCSI Storage Node allow coordinated access to that node.
A PG object MAY be registered when a Portal or iSCSI Storage Node is
registered. Each Portal to iSCSI Node association is represented by
one and only one PG object. In order for a Portal to provide access
to an iSCSI Node, the PGT of the PG object MUST be non-NULL. If the
PGT value registered for a specified Portal and iSCSI Node is NULL,
or if no PGT value is registered, then the Portal does not provide
access to that iSCSI Node in the Entity.
The PGT value indicates whether access to an iSCSI Node can be
coordinated across multiple Portals. All Portals that have the same
PGT value for a specific iSCSI Node can provide coordinated access to
that iSCSI Node. According to the iSCSI Specification, coordinated
access to an iSCSI node indicates the capability of coordinating an
iSCSI session with connections that span these Portals [iSCSI].
The PG object is uniquely distinguished by the iSCSI Name, Portal IP
Address, and Portal TCP Port values of the associated Storage Node
and Portal objects. These are represented in the iSNS Server by the
PG iSCSI Name, PG Portal IP Address, and PG Portal TCP/UDP Port
attributes, respectively. The PG object is also uniquely
distinguished in the iSNS Server by the PG Index value.
A new PG object can only be registered by referencing its associated
iSCSI Storage Node or Portal object. A pre-existing PG object can be
modified or queried by using its Portal Group Index as message key,
or by referencing its associated iSCSI Storage Node or Portal object.
A 0-length Tag, Length, Value TLV is used to register a PGT NULL
value.
The PG object is deregistered if and only if its associated iSCSI
Node and Portal objects are both removed.
Tseng, et al. Standards Track [Page 23]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
3.5. Device Object
The FC Device represents the Fibre Channel Node. This object
contains information that may be useful in the management of the
Fibre Channel device. The FC Node Name (WWNN) attribute uniquely
distinguishes an FC Device, and is the key used to register an FC
Device object in the iSNS Server.
The FC Device is contained in one or more Storage Node objects.
3.6. Discovery Domain Object
Discovery Domains (DD) are a security and management mechanism used
to administer access and connectivity to storage devices. For query
and registration purposes, they are considered containers for Storage
Node and Portal objects. A query by an iSNS client that is not from
a Control Node only returns information about objects with which it
shares at least one active DD. The only exception to this rule is
with Portals; if Storage Nodes of a Network Entity are registered in
the DD without Portals, then all Portals of that Network Entity are
implicit members of that DD. The Discovery Domain ID (DD_ID)
attribute uniquely distinguishes a Discovery Domain object, and is
the key used to register a Discovery Domain object in the iSNS
Server.
A DD is considered active if it is a member of at least one active DD
Set. DDs that are not members of at least one enabled DDS are
considered disabled. A Storage Node can be a member of one or more
DDs. An enabled DD establishes connectivity among the Storage Nodes
in that DD.
3.7. Discovery Domain Set Object
The Discovery Domain Set (DDS) is a container object for Discovery
Domains (DDs). DDSs may contain one or more DDs. Similarly, each DD
can be a member of one or more DDSs. DDSs are a mechanism to store
coordinated sets of DD mappings in the iSNS server. Active DDs are
members of at least one active DD Set. Multiple DDSs may be
considered active at the same time. The Discovery Domain Set ID
(DDS_ID) attribute uniquely distinguishes a Discovery Domain Set
object, and is the key used to register a Discovery Domain Set object
in the iSNS Server.
3.8. Database Model
As presented to the iSNS client, each object of a specific type in
the iSNS database MUST have an implicit internal linear ordering
based on the key(s) for that object type. This ordering provides the
Tseng, et al. Standards Track [Page 24]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
ability to respond to DevGetNext queries (see Section 5.6.5.3). The
ordering of objects in the iSNS database SHOULD NOT be changed with
respect to that implied ordering, as a consequence of object
insertions and deletions. That is, the relative order of surviving
object entries in the iSNS database SHOULD be preserved so that the
DevGetNext message encounters generally reasonable behavior.
The following diagram shows the various objects described above and
their relationship to each other.
+--------------+ +-----------+
| NETWORK |1 *| |
| ENTITY |----| PORTAL |
| | | |
+--------------+ +-----------+
|1 |1 |*
| | |
| |* |
| +----------+ |
| | PORTAL | |
| | GROUP | |
| +----------+ |
| |* |
| | |
|* |1 |*
+-----------+ +--------------+ +-----------+ +-----------+
| FC |1 *| STORAGE |* *| DISCOVERY |* *| DISCOVERY |
| DEVICE |----| NODE |----| DOMAIN |----| DOMAIN |
| | | | | | | SET |
+-----------+ +--------------+ +-----------+ +-----------+
* represents 0 to many possible relationships
4. iSNS Implementation Requirements
This section details specific requirements for support of each of
these IP storage protocols. Implementation requirements for security
are described in Section 7.
4.1. iSCSI Requirements
Use of iSNS in support of iSCSI is OPTIONAL. iSCSI devices MAY be
manually configured with the iSCSI Name and IP address of peer
devices, without the aid or intervention of iSNS. iSCSI devices may
also use SLP [RFC2608] to discover peer iSCSI devices. However, iSNS
is useful for scaling a storage network to a larger number of iSCSI
devices.
Tseng, et al. Standards Track [Page 25]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
4.1.1. Required Attributes for Support of iSCSI
The following attributes are available to support iSCSI. Attributes
indicated in the REQUIRED for Server column MUST be implemented by an
iSNS server used to support iSCSI. Attributes indicated in the
REQUIRED for Client column MUST be implemented by an iSCSI device
that elects to use the iSNS. Attributes indicated in the K (Key)
column uniquely identify the object type in the iSNS Server. A more
detailed description of each attribute is found in Section 6.
REQUIRED for:
Object Attribute K Server Client
------ --------- - ------ ------
NETWORK ENTITY Entity Identifier * * *
Entity Protocol * *
Management IP Address *
Timestamp *
Protocol Version Range *
Registration Period *
Entity Index *
Entity IKE Phase-1 Proposal
Entity Certificate
PORTAL IP Address * * *
TCP/UDP Port * * *
Portal Symbolic Name *
ESI Interval *
ESI Port *
Portal Index *
SCN Port *
Portal Security Bitmap *
Portal IKE Phase-1 Proposal
Portal IKE Phase-2 Proposal
Portal Certificate
PORTAL GROUP PG iSCSI Name * * *
PG IP Address * * *
PG TCP/UDP Port * * *
PG Tag * *
PG Index *
Tseng, et al. Standards Track [Page 26]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
STORAGE NODE iSCSI Name * * *
iSCSI Node Type * *
Alias *
iSCSI SCN Bitmap *
iSCSI Node Index *
WWNN Token
iSCSI AuthMethod
iSCSI Node Certificate
DISCOVERY DOMAIN DD ID * * *
DD Symbolic Name *
DD Member iSCSI Node Index *
DD Member iSCSI Name *
DD Member Portal Index *
DD Member Portal IP Addr *
DD Member Portal TCP/UDP *
DD Features *
DISCOVERY DOMAIN DDS Identifier * *
SET DDS Symbolic Name *
DDS Status *
All iSCSI user-specified and vendor-specified attributes are OPTIONAL
to implement and use.
Tseng, et al. Standards Track [Page 27]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
4.1.2. Examples: iSCSI Object Model Diagrams
The following diagram models how a simple iSCSI-based initiator and
target is represented using database objects stored in the iSNS
server. In this implementation, each target and initiator is
attached to a single Portal.
+----------------------------------------------------------------+
| IP Network |
+------------+--------------------------------------+------------+
| |
| |
+-----+------+------+-----+ +-----+------+------+-----+
| | PORTAL | | | | PORTAL | |
| | -IP Addr 1 | | | | -IP Addr 2 | |
| | -TCP Port 1 | | | | -TCP Port 2 | |
| +-----+ +-----+ | | +-----+ +-----+ |
| | | | | | | |
| +-----+ +-----+ | | +-----+ +-----+ |
| | PORTAL GROUP| | | | PORTAL GROUP| |
| | -Prtl Tag 1 | | | | -Prtl Tag 2 | |
| +-----+ +-----+ | | +-----+ +-----+ |
| | | | | | | |
| +--------+ +--------+ | | +-------+ +--------+ |
| | | | | | | |
| | STORAGE NODE | | | | STORAGE NODE | |
| | -iSCSI Name | | | | -iSCSI Name | |
| | -Alias: "server1"| | | | -Alias: "disk1"| |
| | -Type: initiator | | | | -Type: target | |
| | | | | | | |
| +-------------------+ | | +------------------+ |
| | | |
| NETWORK ENTITY | | NETWORK ENTITY |
| -Entity ID (FQDN): | | -Entity ID (FQDN): |
| "strg1.example.com" | | "strg2.example.net" |
| -Protocol: iSCSI | | -Protocol: iSCSI |
| | | |
+-------------------------+ +-------------------------+
The object model can be expanded to describe more complex devices,
such as an iSCSI device with more than one storage controller, in
which each controller is accessible through any of multiple Portal
interfaces, possibly using multiple Portal Groups. The storage
controllers on this device can be accessed through alternate Portal
interfaces if any original interface should fail. The following
diagram describes such a device:
Tseng, et al. Standards Track [Page 28]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
+---------------------------------------------------------------+
| IP Network |
+-------------------+-----------------------+-------------------+
| |
| |
+------------+------+------+---------+------+------+------------+
| | PORTAL 1 | | PORTAL 2 | |
| | -IP Addr 1 | | -IP Addr 2 | |
| | -TCP Port 1 | | -TCP Port 2 | |
| +-----+ +-----+ +-----+ +-----+ |
| | | | | |
| +---------------+ +---------------------+ +---------------+ |
| +-------+ +----------------+ +-------------------+ +------+ |
| | | | | | | |
| +-------+ +-------+ +------+ +--------+ +--------+ +------+ |
| | | | | | | |
| | STORAGE NODE 1 | | STORAGE NODE 2 | | STORAGE NODE 3 | |
| | -iSCSI Name 1 | | -iSCSI Name 2 | | -iSCSI Name 3 | |
| | -Alias: "disk1"| | -Alias: "disk2"| | -Alias: "disk3"| |
| | -Type: target | | -Type: target | | -Type: target | |
| | | | | | | |
| +-----------------+ +-----------------+ +-----------------+ |
| |
| NETWORK ENTITY |
| -Entity ID (FQDN): "dev1.example.com" |
| -Protocol: iSCSI |
| |
| Portal Group Object Table |
| Storage-Node Portal Portal-Group-Tag |
| 1 1 10 |
| 1 2 NULL (no access permitted) |
| 2 1 20 |
| 2 2 20 |
| 3 1 30 |
| 3 2 10 |
| |
+---------------------------------------------------------------+
Storage Node 1 is accessible via Portal 1 with a PGT of 10. It does
not have a Portal Group Tag (PGT) assigned for Portal 2, so Storage
Node 1 cannot be accessed via Portal 2.
Storage Node 2 can be accessed via both Portal 1 and Portal 2. Since
Storage Node 2 has the same PGT value assigned to both Portal 1 and
Portal 2, in this case 20, coordinated access via the Portals is
available [iSCSI].
Tseng, et al. Standards Track [Page 29]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Storage Node 3 can be accessed via Portal 1 or Portal 2. However,
since Storage Node 3 has different PGT values assigned to each
Portal, in this case 10 and 30, access is not coordinated [iSCSI].
Because PGTs are assigned within the context of a Storage Node, the
PGT value of 10 used for Storage Node 1 and Storage Node 3 are not
interrelated.
4.1.3. Required Commands and Response Messages for Support of iSCSI
The following iSNSP messages and responses are available in support
of iSCSI. Messages indicated in the REQUIRED for Server column MUST
be implemented in iSNS servers used for iSCSI devices. Messages
indicated in the REQUIRED for Client column MUST be implemented in
iSCSI devices that elect to use the iSNS server.
REQUIRED for:
Message Description Abbreviation Func_ID Server Client
------------------- ------------ ------- ------ ------
RESERVED 0x0000
Device Attr Reg Request DevAttrReg 0x0001 * *
Dev Attr Query Request DevAttrQry 0x0002 * *
Dev Get Next Request DevGetNext 0x0003 *
Deregister Dev Request DevDereg 0x0004 * *
SCN Register Request SCNReg 0x0005 *
SCN Deregister Request SCNDereg 0x0006 *
SCN Event SCNEvent 0x0007 *
State Change Notification SCN 0x0008 *
DD Register DDReg 0x0009 * *
DD Deregister DDDereg 0x000A * *
DDS Register DDSReg 0x000B * *
DDS Deregister DDSDereg 0x000C * *
Entity Status Inquiry ESI 0x000D *
Name Service Heartbeat Heartbeat 0x000E
RESERVED 0x000F-0x00FF
Vendor Specific 0x0100-0x01FF
RESERVED 0x0200-0x7FFF
The following are iSNSP response messages used in support of iSCSI:
REQUIRED for:
Response Message Desc Abbreviation Func_ID Server Client
--------------------- ------------ ------- ------ ------
RESERVED 0x8000
Device Attr Register Rsp DevAttrRegRsp 0x8001 * *
Device Attr Query Rsp DevAttrQryRsp 0x8002 * *
Device Get Next Rsp DevGetNextRsp 0x8003 *
Device Dereg Rsp DevDeregRsp 0x8004 * *
SCN Register Rsp SCNRegRsp 0x8005 *
Tseng, et al. Standards Track [Page 30]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
SCN Deregister Rsp SCNDeregRsp 0x8006 *
SCN Event Rsp SCNEventRsp 0x8007 *
SCN Response SCNRsp 0x8008 *
DD Register Rsp DDRegRsp 0x8009 * *
DD Deregister Rsp DDDeregRsp 0x800A * *
DDS Register Rsp DDSRegRsp 0x800B * *
DDS Deregister Rsp DDSDeregRsp 0x800C * *
Entity Stat Inquiry Rsp ESIRsp 0x800D *
RESERVED 0x800E-0x80FF
Vendor Specific 0x8100-0x81FF
RESERVED 0x8200-0xFFFF
4.2. iFCP Requirements
In iFCP, use of iSNS is REQUIRED. No alternatives exist for support
of iFCP Naming & Discovery functions.
4.2.1. Required Attributes for Support of iFCP
The following table displays attributes that are used by iSNS to
support iFCP. Attributes indicated in the REQUIRED for Server column
MUST be implemented by the iSNS server that supports iFCP.
Attributes indicated in the REQUIRED for Client column MUST be
supported by iFCP gateways. Attributes indicated in the K (Key)
column uniquely identify the object type in the iSNS Server. A more
detailed description of each attribute is found in Section 6.
REQUIRED for:
Object Attribute K Server Client
------ --------- - ------ ------
NETWORK ENTITY Entity Identifier * * *
Entity Protocol * *
Management IP Address *
Timestamp *
Protocol Version Range *
Registration period
Entity Index
Entity IKE Phase-1 Proposal
Entity Certificate
PORTAL IP Address * * *
TCP/UDP Port * * *
Symbolic Name *
ESI Interval *
ESI Port *
SCN Port *
Portal IKE Phase-1 Proposal
Portal IKE Phase-2 Proposal
Tseng, et al. Standards Track [Page 31]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Portal Certificate
Security Bitmap *
STORAGE NODE FC Port Name (WWPN) * * *
(FC Port) Port_ID * *
FC Port Type * *
Port Symbolic Name *
Fabric Port Name (FWWN) *
Hard Address *
Port IP Address *
Class of Service *
FC FC-4 Types *
FC FC-4 Descriptors *
FC FC-4 Features *
SCN Bitmap *
iFCP Port Role *
Permanent Port Name *
FC DEVICE FC Node Name (WWNN) * * *
(FC Node) Node Symbolic Name *
Node IP Address *
Node IPA *
Proxy iSCSI Name
DISCOVERY DOMAIN DD ID * * *
DD Symbolic Name *
DD Member FC Port Name *
DD Member Portal Index *
DD Member Portal IP Addr *
DD Member Portal TCP/UDP *
DISCOVERY DOMAIN DDS ID * *
SET DDS Symbolic Name *
DDS Status *
OTHER Switch Name
Preferred_ID
Assigned_ID
Virtual_Fabric_ID
All iFCP user-specified and vendor-specified attributes are OPTIONAL
to implement and use.
4.2.2. Example: iFCP Object Model Diagram
The iFCP protocol allows native Fibre Channel devices or Fibre
Channel fabrics connected to an iFCP gateway to be directly
internetworked using IP.
Tseng, et al. Standards Track [Page 32]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
When supporting iFCP, the iSNS server stores Fibre Channel device
attributes, iFCP gateway attributes, and Fibre Channel fabric switch
attributes that might also be stored in an FC name server.
The following diagram shows a representation of a gateway supporting
multiple Fibre Channel devices behind it. The two Portal objects
represent IP interfaces on the iFCP gateway that can be used to
access any of the three Storage Node objects behind it. Note that
the FC Device object is not contained in the Network Entity object.
However, each FC Device has a relationship to one or more Storage
Node objects.
+--------------------------------------------------------+
| IP Network |
+--------+-----------------+-----------------------------+
| |
+-+------+------+---+------+------+----------------------+
| | PORTAL | | PORTAL | NETWORK ENTITY |
| | -IP Addr 1 | | -IP Addr 2 | -Entity ID (FQDN): |
| | -TCP Port 1 | | -TCP Port 2 | "gtwy1.example.com" |
| +-----+ +-----+ +-----+ +-----+ -Protocol: iFCP |
| | | | | |
| +-----+ +---------------+ +----------------------+ |
| +-----+ +---------------+ +-------------+ +------+ |
| | | | | | | |
| +-----+ +-----+ +----+ +------+ +----+ +------+ |
| |STORAGE NODE | |STORAGE NODE | |STORAGE NODE | |
| | -WWPN 1 | | -WWPN 2 | | -WWPN 3 | |
| | -Port ID 1 | | -Port ID 2 | | -Port ID 3 | |
| | -FWWN 1 | | -FWWN 2 | | -FWWN 3 | |
| | -FC COS | | -FC COS | | -FC COS | |
| +------+------+ +-------+-----+ +----+--------+ |
+--------|-------------------|------------|--------------+
| | |
+------+------+ +---+------------+---+
| FC DEVICE | | FC DEVICE |
| -WWNN 1 | | -WWNN 2 |
| | | |
+-------------+ +--------------------+
Tseng, et al. Standards Track [Page 33]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
4.2.3. Required Commands and Response Messages for Support of iFCP
The iSNSP messages and responses displayed in the following tables
are available to support iFCP gateways. Messages indicated in the
REQUIRED TO IMPLEMENT column MUST be supported by the iSNS server
used by iFCP gateways. Messages indicated in the REQUIRED TO USE
column MUST be supported by the iFCP gateways themselves.
REQUIRED for:
Message Description Abbreviation Func ID Server Client
------------------- ------------ ------- ------ ------
RESERVED 0x0000
Device Attr Reg Request DevAttrReg 0x0001 * *
Device Attr Query Request DevAttrQry 0x0002 * *
Device Get Next Request DevGetNext 0x0003 *
Device Dereg Request DevDereg 0x0004 * *
SCN Register Request SCNReg 0x0005 *
SCN Deregister Request SCNDereg 0x0006 *
SCN Event SCNEvent 0x0007 *
State Change Notification SCN 0x0008 *
DD Register DDReg 0x0009 * *
DD Deregister DDDereg 0x000A * *
DDS Register DDSReg 0x000B * *
DDS Deregister DDSDereg 0x000C * *
Entity Status Inquiry ESI 0x000D *
Name Service Heartbeat Heartbeat 0x000E *
Reserved Reserved 0x000F-0x0010
Request FC_DOMAIN_ID RqstDomId 0x0011
Release FC_DOMAIN_ID RlseDomId 0x0012
Get FC_DOMAIN_IDs GetDomId 0x0013
RESERVED 0x0014-0x00FF
Vendor Specific 0x0100-0x01FF
RESERVED 0x0200-0x7FFF
The following are iSNSP response messages in support of iFCP:
REQUIRED for:
Response Message Desc Abbreviation Func_ID Server Client
--------------------- ------------ ------- ------ ------
RESERVED 0x8000
Device Attr Reg Rsp DevAttrRegRsp 0x8001 * *
Device Attr Query Rsp DevAttrQryRsp 0x8002 * *
Device Get Next Rsp DevGetNextRsp 0x8003 *
Device Deregister Rsp DevDeregRsp 0x8004 * *
SCN Register Rsp SCNRegRsp 0x8005 *
SCN Deregister Rsp SCNDeregRsp 0x8006 *
SCN Event Rsp SCNEventRsp 0x8007 *
SCN Rsp SCNRsp 0x8008 *
Tseng, et al. Standards Track [Page 34]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
DD Register Rsp DDRegRsp 0x8009 * *
DD Deregister Rsp DDDeregRsp 0x800A * *
DDS Register Rsp DDSRegRsp 0x800B * *
DDS Deregister Rsp DDSDeregRsp 0x800C * *
Entity Status Inquiry Rsp ESIRsp 0x800D *
NOT USED 0x800E
RESERVED 0x800F-0x8010
Request FC_DOMAIN_ID Rsp RqstDomIdRsp 0x8011
Release FC_DOMAIN_ID Rsp RlseDomIdRsp 0x8012
Get FC_DOMAIN_IDs GetDomIdRsp 0x0013
RESERVED 0x8014-0x80FF
Vendor Specific 0x8100-0x81FF
RESERVED 0x8200-0xFFFF
5. iSNSP Message Format
The iSNSP message format is similar to the format of other common
protocols such as DHCP, DNS and BOOTP. An iSNSP message may be sent
in one or more iSNS Protocol Data Units (PDU). Each PDU is 4-byte
aligned. The following describes the format of the iSNSP PDU:
Byte MSb LSb
Offset 0 15 16 31
+---------------------+----------------------+
0 | iSNSP VERSION | FUNCTION ID | 4 Bytes
+---------------------+----------------------+
4 | PDU LENGTH | FLAGS | 4 Bytes
+---------------------+----------------------+
8 | TRANSACTION ID | SEQUENCE ID | 4 Bytes
+---------------------+----------------------+
12 | |
| PDU PAYLOAD | N Bytes
| ... |
+--------------------------------------------+
12+N | AUTHENTICATION BLOCK (Multicast/Broadcast) | L Bytes
+--------------------------------------------+
Total Length = 12 + N + L
5.1. iSNSP PDU Header
The iSNSP PDU header contains the iSNSP VERSION, FUNCTION ID, PDU
LENGTH, FLAGS, TRANSACTION ID, and SEQUENCE ID fields as defined
below.
Tseng, et al. Standards Track [Page 35]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.1.1. iSNSP Version
The iSNSP version described in this document is 0x0001. All other
values are RESERVED. The iSNS server MAY reject messages for iSNSP
version numbers that it does not support.
5.1.2. iSNSP Function ID
The FUNCTION ID defines the type of iSNS message and the operation to
be executed. FUNCTION_ID values with the leading bit cleared
indicate query, registration, and notification messages, whereas
FUNCTION_ID values with the leading bit set indicate response
messages.
See Section 4 under the appropriate protocol (i.e., iSCSI or iFCP)
for a mapping of the FUNCTION_ID value to the iSNSP Command or
Response message. All PDUs comprising an iSNSP message must have the
same FUNCTION_ID value.
5.1.3. iSNSP PDU Length
The iSNS PDU Length specifies the length of the PDU PAYLOAD field in
bytes. The PDU Payload contains TLV attributes for the operation.
Additionally, response messages contain a success/failure code. The
PDU Length MUST be 4-byte aligned.
5.1.4. iSNSP Flags
The FLAGS field indicates additional information about the message
and the type of Network Entity that generated the message. The
following table displays the valid flags:
Bit Position Enabled (1) means:
------------ -----------------
16 Sender is the iSNS client
17 Sender is the iSNS server
18 Authentication block is present
19 Replace flag (for DevAttrReg)
20 Last PDU of the iSNS message
21 First PDU of the iSNS message
22-31 RESERVED
5.1.5. iSNSP Transaction ID
The TRANSACTION ID MUST be set to a unique value for each
concurrently outstanding request message. Replies MUST use the same
TRANSACTION ID value as the associated iSNS request message. If a
Tseng, et al. Standards Track [Page 36]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
message is retransmitted, the original TRANSACTION ID value MUST be
used. All PDUs comprising an iSNSP message must have the same
TRANSACTION ID value.
5.1.6. iSNSP Sequence ID
The SEQUENCE ID has a unique value for each PDU within a single
transaction. The SEQUENCE_ID value of the first PDU transmitted in a
given iSNS message MUST be zero (0), and each SEQUENCE_ID value in
each PDU MUST be numbered sequentially in the order in which the PDUs
are transmitted. Note that the two-byte SEQUENCE ID allows for up to
65536 PDUs per iSNS message.
5.2. iSNSP Message Segmentation and Reassembly
iSNS messages may be carried in one or more iSNS PDUs. If only one
iSNS PDU is used to carry the iSNS message, then bit 21 (First PDU)
and bit 20 in the FLAGS field (Last PDU) SHALL both be set. If
multiple PDUs are used to carry the iSNS message, then bit 21 SHALL
be set in the first PDU of the message, and bit 20 SHALL be set in
the last PDU.
All PDUs comprising the same iSNSP message SHALL have the same
FUNCTION_ID and TRANSACTION_ID values. Each PDU comprising an iSNSP
message SHALL have a unique SEQUENCE_ID value.
5.3. iSNSP PDU Payload
The iSNSP PDU PAYLOAD is of variable length and contains attributes
used for registration and query operations. The attribute data items
use a format similar to that of other protocols, such as DHCP
[RFC2131] options. Each iSNS attribute is specified in the PDU
Payload using Tag-Length-Value (TLV) data format, as shown below:
Byte MSb LSb
Offset 0 31
+--------------------------------------------+
0 | Attribute Tag | 4 Bytes
+--------------------------------------------+
4 | Attribute Length (N) | 4 Bytes
+--------------------------------------------+
8 | |
| Attribute Value | N Bytes
| |
+--------------------------------------------+
Total Length = 8 + N
Tseng, et al. Standards Track [Page 37]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Attribute Tag: a 4-byte field that identifies the attribute as
defined in Section 6.1. This field contains the
tag value from the indicated table.
Attribute Length: a 4-byte field that indicates the length, in bytes,
of the value field to follow in the TLV. For
variable-length attributes, the value field MUST
contain padding bytes, if necessary, in order to
achieve 4-byte alignment. A "zero-length TLV"
contains only the attribute tag and length fields.
Attribute Value: a variable-length field containing the attribute
value and padding bytes (if necessary).
The above format is used to identify each attribute in the PDU
Payload. Note that TLV boundaries need not be aligned with PDU
boundaries; PDUs may carry one or more TLVs, or any fraction thereof.
The Response Status Code, contained in response message PDU Payloads
and described below, is not in TLV format. PDU Payloads for messages
that do not contain iSNS attributes, such as the Name Service
Heartbeat, do not use the TLV format.
5.3.1. Attribute Value 4-Byte Alignment
All attribute values are aligned to 4-byte boundaries. For variable
length attributes, if necessary, the TLV length MUST be increased to
the next 4-byte boundary through padding with bytes containing zero
(0). If an attribute value is padded, a combination of the tag and
attribute value itself is used to determine the actual value length
and number of pad bytes. There is no explicit count of the number of
pad bytes provided in the TLV.
Tseng, et al. Standards Track [Page 38]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.4. iSNSP Response Status Codes
All iSNSP response messages contain a 4-byte Status Code field as the
first field in the iSNSP PDU PAYLOAD. If the original iSNSP request
message was processed normally by the iSNS server, or by the iSNS
client for ESI and SCN messages, then this field SHALL contain a
status code of 0 (Successful). A non-zero status code indicates
rejection of the entire iSNS client request message.
Status Code Status Description
----------- -----------------
0 Successful
1 Unknown Error
2 Message Format Error
3 Invalid Registration
4 RESERVED
5 Invalid Query
6 Source Unknown
7 Source Absent
8 Source Unauthorized
9 No Such Entry
10 Version Not Supported
11 Internal Error
12 Busy
13 Option Not Understood
14 Invalid Update
15 Message (FUNCTION_ID) Not Supported
16 SCN Event Rejected
17 SCN Registration Rejected
18 Attribute Not Implemented
19 FC_DOMAIN_ID Not Available
20 FC_DOMAIN_ID Not Allocated
21 ESI Not Available
22 Invalid Deregistration
23 Registration Feature Not Supported
24 and above RESERVED
5.5. Authentication for iSNS Multicast and Broadcast Messages
For iSNS multicast and broadcast messages (see Section 2.9.3), the
iSNSP provides authentication capability. The following section
details the iSNS Authentication Block, which is identical in format
to the SLP authentication block [RFC2608]. iSNS unicast messages
SHOULD NOT include the authentication block, but rather should rely
upon IPSec security mechanisms.
Tseng, et al. Standards Track [Page 39]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
If a message contains an authentication block, then the
"Authentication block present" bit in the iSNSP PDU header FLAGS
field SHALL be enabled.
If a PKI is available with an [X.509] Certificate Authority (CA),
then public key authentication of the iSNS server is possible. The
authentication block leverages the DSA with SHA-1 algorithm, which
can easily integrate into a public key infrastructure.
The authentication block contains a digital signature for the
multicast message. The digital signature is calculated on a per-PDU
basis. The authentication block contains the following information:
1. A time stamp, to prevent replay attacks.
2. A structured authenticator containing a signature calculated over
the time stamp and the message being secured.
3. An indicator of the cryptographic algorithm that was used to
calculate the signature.
4. An indicator of the keying material and algorithm parameters,
used to calculate the signature.
The authentication block is described in the following figure:
Byte MSb LSb
Offset 0 31
+----------------------------------+
0 | BLOCK STRUCTURE DESCRIPTOR | 4 Bytes
+----------------------------------+
4 | AUTHENTICATION BLOCK LENGTH | 4 Bytes
+----------------------------------+
8 | TIMESTAMP | 8 Bytes
+----------------------------------+
16 | SPI STRING LENGTH | 4 Bytes
+----------------------------------+
20 | SPI STRING | N Bytes
+----------------------------------+
20 + N | STRUCTURED AUTHENTICATOR | M Bytes
+----------------------------------+
Total Length = 20 + N + M
BLOCK STRUCTURE DESCRIPTOR (BSD): Defines the structure and algorithm
to use for the STRUCTURED AUTHENTICATOR. BSD values from
0x00000000 to 0x00007FFF are assigned by IANA, while
values 0x00008000 to 0x00008FFF are for private use.
Tseng, et al. Standards Track [Page 40]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
AUTHENTICATION BLOCK LENGTH: Defines the length of the authentication
block, beginning with the BSD field and running through
the last byte of the STRUCTURED AUTHENTICATOR.
TIMESTAMP: This is an 8-byte unsigned, fixed-point integer giving the
number of seconds since 00:00:00 GMT on January 1, 1970.
SPI STRING LENGTH: The length of the SPI STRING field.
SPI STRING (Security Parameters Index): Index to the key and
algorithm used by the message recipient to decode the
STRUCTURED AUTHENTICATOR field.
STRUCTURED AUTHENTICATOR: Contains the digital signature. For the
default BSD value of 0x0002, this field SHALL contain the
binary ASN.1 encoding of output values from the DSA with
SHA-1 signature calculation as specified in Section 2.2.2
of [RFC3279].
5.6. Registration and Query Messages
The iSNSP registration and query message PDU Payloads contain a list
of attributes, and have the following format:
+----------------------------------------+
| Source Attribute (Requests Only) |
+----------------------------------------+
| Message Key Attribute[1] (if present) |
+----------------------------------------+
| Message Key Attribute[2] (if present) |
+----------------------------------------+
| . . . |
+----------------------------------------+
| - Delimiter Attribute - |
+----------------------------------------+
| Operating Attribute[1] (if present) |
+----------------------------------------+
| Operating Attribute[2] (if present) |
+----------------------------------------+
| Operating Attribute[3] (if present) |
+----------------------------------------+
| . . . |
+----------------------------------------+
Each Source, Message Key, Delimiter, and Operating attribute is
specified in the PDU Payload using the Tag-Length-Value (TLV) data
format. iSNS Registration and Query messages are sent by iSNS Clients
Tseng, et al. Standards Track [Page 41]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
to the iSNS server IP Address and well-known TCP/UDP Port. The iSNS
Responses will be sent to the iSNS Client IP address and TCP/UDP port
number from the original request message.
5.6.1. Source Attribute
The Source Attribute is used to identify the Storage Node to the iSNS
server for queries and other messages that require source
identification. The Source Attribute uniquely identifies the source
of the message. Valid Source Attribute types are shown below.
Valid Source Attributes
-----------------------
iSCSI Name
FC Port Name WWPN
For a query operation, the Source Attribute is used to limit the
scope of the specified operation to the Discovery Domains of which
the source is a member. Special Control Nodes, identified by the
Source Attribute, may be administratively configured to perform the
specified operation on all objects in the iSNS database without
scoping to Discovery Domains.
For messages that change the contents of the iSNS database, the iSNS
server MUST verify that the Source Attribute identifies either a
Control Node or a Storage Node that is a part of the Network Entity
containing the added, deleted, or modified objects.
5.6.2. Message Key Attributes
Message Key attributes are used to identify matching objects in the
iSNS database for iSNS query and registration messages. If present,
the Message Key MUST be a Registration or Query Key for an object as
described in Sections 5.6.5 and 6.1. A Message Key is not required
when a query spans the entire set of objects available to the Source
or a registration is for a new Entity.
iSCSI Names used in the Message Key MUST be normalized according to
the stringprep template [STRINGPREP]. Entity Identifiers (EIDs) used
in the Message Key MUST be normalized according to the nameprep
template [NAMEPREP].
5.6.3. Delimiter Attribute
The Delimiter Attribute separates the Message Key attributes from the
Operating Attributes in a PDU Payload. The Delimiter Attribute has a
tag value of 0 and a length value of 0. The Delimiter Attribute is
always 8 bytes long (a 4-byte tag field and a 4-byte length field,
Tseng, et al. Standards Track [Page 42]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
all containing zeros). If a Message Key is not required for a
message, then the Delimiter Attribute immediately follows the Source
Attribute.
5.6.4. Operating Attributes
The Operating Attributes are a list of one or more key and non-key
attributes related to the actual iSNS registration or query operation
being performed.
Operating Attributes include object key attributes and non-key
attributes. Object key attributes uniquely identify iSNS objects.
Key attributes MUST precede the non-key attributes of each object in
the Operating Attributes. The tag value distinguishes the attribute
as an object key attribute (i.e., tag=1, 16&17, 32, 64, and 96) or a
non-key attribute. iSCSI Names used in the Operating Attributes MUST
be normalized according to the stringprep template [STRINGPREP].
Entity Identifiers (EIDs) used in the Operating Attributes MUST be
normalized according to the nameprep template [NAMEPREP].
The ordering of Operating Attributes in the message is important for
determining the relationships among objects and their ownership of
non-key attributes. iSNS protocol messages that violate these
ordering rules SHALL be rejected with the Status Code of 2 (Message
Format Error). See the message descriptions for proper operating
attribute ordering requirements.
Some objects are keyed by more than one object key attribute value.
For example, the Portal object is keyed by attribute tags 16 and 17.
When describing an object keyed by more than one key attribute, every
object key attribute of that object MUST be listed sequentially by
tag value in the message before non-key attributes of that object and
key attributes of the next object. A group of key attributes of this
kind is treated as a single logical key attribute when identifying an
object.
Non-key attributes that immediately follow key attributes MUST be
attributes of the object referenced by the key attributes. All non-
key attributes of an object MUST be listed before the object key
attributes introducing the next object.
Objects MUST be listed in inheritance order, according to their
containment order. Storage Node and Portal objects and their
respective attributes MUST follow the Network Entity object to which
they have a relationship. Similarly, FC Device objects MUST follow
the Storage Node object to which they have a relationship.
Tseng, et al. Standards Track [Page 43]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Vendor-specific objects defined by tag values in the range 1537-2048
have the same requirements described above.
5.6.4.1. Operating Attributes for Query and Get Next Requests
In Query and Get Next request messages, TLV attributes with length
value of 0 are used to indicate which Operating Attributes are to be
returned in the corresponding response. Operating Attribute values
that match the TLV attributes in the original message are returned in
the response message.
5.6.5. Registration and Query Request Message Types
The following describes each query and message type.
5.6.5.1. Device Attribute Registration Request (DevAttrReg)
The DevAttrReg message type is 0x0001. The DevAttrReg message
provides the means for iSNS clients to update existing objects or
register new objects. The value of the replace bit in the FLAGs
field determines whether the DevAttrReg message updates or replaces
an existing registration.
The Source Attribute identifies the Node initiating the registration
request.
The Message Key identifies the object the DevAttrReg message acts
upon. It MUST contain the key attribute(s) identifying an object.
This object MUST contain all attributes and related subordinate
object attributes that will be included in the Operating Attributes
of the DevAttrReg PDU Payload. The key attribute(s) identifying this
object MUST also be included among the Operating Attributes.
If the Message Key contains an EID and no pre-existing objects match
the Message Key, then the DevAttrReg message SHALL create a new
Entity with the specified EID and any new object(s) specified by the
Operating Attributes. The replace bit SHALL be ignored.
If the Message Key does not contain an EID, and no pre-existing
objects match the Message Key, then the DevAttrReg message SHALL be
rejected with a status code of 3 (Invalid Registration).
If the Message Key is not present, then the DevAttrReg message
implicitly registers a new Network Entity. In this case, the replace
bit SHALL be ignored; a new Network Entity SHALL be created.
Existing entities, their objects, and their relationships remain
unchanged.
Tseng, et al. Standards Track [Page 44]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
The replace bit determines the kind of operation conducted on the
object identified in the DevAttrReg Message Key. The replace bit
only applies to the DevAttrReg message; it is ignored for all other
message types.
If the replace bit is set, then the objects, attributes, and
relationships specified in the Operating Attributes SHALL replace the
object identified by the Message Key. The object and all of its
subordinate objects SHALL be deregistered, and the appropriate SCNs
SHALL be sent by the iSNS server for the deregistered objects. The
objects listed in the Operating Attributes are then used to replace
the just-deregistered objects. Note that additional SCNs SHALL be
sent for the newly-registered objects, if appropriate. Existing
objects and relationships that are not identified or that are
subordinate to the object identified by the Message Key MUST NOT be
affected or changed.
If the replace bit is not set, then the message updates the
attributes of the object identified by the Message Key and its
subordinate objects. Existing object containment relationships MUST
NOT be changed. For existing objects, key attributes MUST NOT be
modified, but new subordinate objects MAY be added.
The Operating Attributes represent objects, attributes, and
relationships that are to be registered. Multiple related objects
and attributes MAY be registered in a single DevAttrReg message. The
ordering of the objects in this message indicates the structure of,
and associations among, the objects to be registered. At least one
object MUST be listed in the Operating Attributes. Additional
objects (if any) MUST be subordinate to the first object listed. Key
attributes MUST precede non-key attributes of each object. A given
object may only appear a maximum of once in the Operating Attributes
of a message. If the Node identified by the Source Attribute is not
a Control Node, then the objects in the operating attributes MUST be
members of the same Network Entity as the Source Node.
For example, to establish relationships between a Network Entity
object and its Portal and Storage Node objects, the Operating
Attributes list the key and non-key attributes of the Network Entity
object, followed by the key and non-key attributes of each Portal and
Storage Node object to be linked to that Network Entity. Similarly,
an FC Device object that follows a Storage Node object is considered
subordinate to that Storage Node.
New PG objects are registered when an associated Portal or iSCSI Node
object is registered. An explicit PG object registration MAY follow
a Portal or iSCSI Node object registration in a DevAttrReg message.
Tseng, et al. Standards Track [Page 45]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
When a Portal is registered, the Portal attributes MAY immediately be
followed by a PGT attribute. The PGT attribute SHALL be followed by
the set of PG iSCSI Names representing nodes that will be associated
to the Portal using the indicated PGT value. Additional sets of PGTs
and PG iSCSI Names to be associated to the registered Portal MAY
follow. Indicated PGT values are assigned to the PG object
associated with the newly registered Portal and to the iSCSI Storage
Node(s) referenced immediately following the PGT attribute in the
operating attributes.
When an iSCSI Storage Node is registered, the Storage Node attributes
MAY immediately be followed by a PGT attribute. The PGT attribute
SHALL be followed by the set of PG Portal IP-Address, PG TCP/UDP Port
pairs representing Portal objects that will be associated with the
Storage Node using the indicated PGT value. Additional sets of PGTs
and PG Portal IP-Address PG TCP/UDP Port pairs to be associated with
the registered Storage Node MAY follow. Indicated PGT values are
assigned to the PG object associated with the newly registered iSCSI
Storage Node and Portal object(s) referenced immediately following
the PGT attribute in the operating attributes.
If the PGT value is not included in the Storage Node or Portal object
registration, and if a PGT value was not previously registered for
the relationship, then the PGT for the corresponding PG object SHALL
be registered with a value of 0x00000001. If the PGT attribute is
included in the registration message as a 0-length TLV, then the PGT
value for the corresponding PG object SHALL be registered as NULL. A
0-length TLV for the PGT in an update registration message overwrites
the previous PGT value with NULL, indicating that there is no
relationship between the Storage Node and Portal.
A maximum of one Network Entity object can be created or updated with
a single DevAttrReg message. Consequently, the Operating Attributes
MUST NOT contain more than one Network Entity object. There is no
limit to the number of Portal, Storage Node, and FC Device objects
that can listed in the Operating Attributes, provided they are all
subordinate to the listed Network Entity object.
If the Message Key and Operating Attributes do not contain an EID
attribute, or if the EID attribute has a length of 0, then a new
Network Entity object SHALL be created and the iSNS server SHALL
supply a unique EID value for it. The assigned EID value SHALL be
included in the DevAttrReg Response message. If the Message Key and
Operating Attributes contain an EID that does not match the EID of an
existing Network Entity in the iSNS database, then a new Network
Entity SHALL be created and assigned the value contained in that EID
attribute. Finally, if the Message Key and Operating Attributes
contain an EID that matches the EID of an existing object in the iSNS
Tseng, et al. Standards Track [Page 46]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
database, then the objects, attributes, and relationships specified
in the Operating Attributes SHALL be appended to the existing Network
Entity identified by the EID.
A registration message that creates a new Network Entity object MUST
contain at least one Portal or one Storage Node. If the message does
not, then it SHALL be considered invalid and result in a response
with Status Code of 3 (Invalid Registration).
If an iSNS Server does not support a registration feature, such as
explicit PG object registration, then the server SHALL return a
Status Code of 23 (Registration Feature Not Supported).
Note that the iSNS server may modify or reject the registration of
certain attributes, such as ESI Interval. In addition, the iSNS
server may assign values for additional Operating Attributes that are
not explicitly registered in the original DevAttrReg message, such as
the EID and WWNN Token.
5.6.5.2. Device Attribute Query Request (DevAttrQry)
The DevAttrQry message type is 0x0002. The DevAttrQry message
provides an iSNS client with the means to query the iSNS server for
object attributes.
The Source Attribute identifies the Node initiating the request. For
non-Control Nodes initiating the DevAttrQry message, the query is
scoped to the Discovery Domains of which the initiating Node is a
member. The DevAttrQry message SHALL only return information on
Storage Nodes and their related parent and subordinate objects, where
the Storage Node has a common Discovery Domain with the Node
identified in the Source Attribute.
The Message Key may contain key or non-key attributes or no
attributes at all. If multiple attributes are used as the Message
Key, then they MUST all be from the same object type (e.g., IP
address and TCP/UDP Port are attributes of the Portal object type).
A Message Key with non-key attributes may match multiple instances of
the specific object type. A Message Key with zero-length TLV(s) is
scoped to every object of the type indicated by the zero-length
TLV(s). An empty Message Key field indicates the query is scoped to
the entire database accessible by the source Node.
The DevAttrQry response message returns attributes of objects listed
in the Operating Attributes that are related to the Message Key of
the original DevAttrQry message. The Operating Attributes of the
DevAttrQry message contain zero-length TLVs that specify the
attributes that are to be returned in the DevAttrQryRsp message. A
Tseng, et al. Standards Track [Page 47]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Message Key containing zero-length TLVs indicates that the set of
attributes specified in the Operating Attributes are to be returned
for each object matching the type indicated by the Message Key.
If the Message Key contains non-zero length TLVs, then Operating
Attributes for the object matching the Message Key SHALL be returned
in the DevAttrQryRsp message. Each attribute type (i.e., zero-length
TLV) in the Operating Attributes indicates an attribute from the
object matching the Message Key, or from other objects in the same
Entity having a relationship to the object matching the Message Key,
is to be returned in the response. The ordering of the object keys
and associated attributes returned in the DevAttrQry response message
SHALL be the same as in the original query message. If no objects
match the Message Key, then the DevAttrQryRsp message SHALL NOT
return any operating attributes. Such a message and its
corresponding response SHALL NOT be considered an error.
The Portal Group object determines whether a relationship exists
between a given Storage Node and Portal object. If the PGT of the
Portal Group is not NULL, then a relationship exists between the
indicated Storage Node and Portal; if the PGT is NULL, then no
relationship exists. Therefore, the value (NULL or not NULL) of the
PGT attribute of each Portal Group object determines the structure
and ordering of the DevAttrQry response to a query for Storage Nodes
and Portals.
For example, an iSNS database contains a Network Entity having two
Portals and two Nodes. Each Storage Node has two Portal Groups, one
with a NULL PGT value for one Portal and another with a non-NULL PGT
value for the other Portal. The DevAttrQry message contains a
Message Key entry matching one of the Nodes, and Operating Attributes
with zero-length TLVs listing first the Node attributes, Portal
attributes, and then the PG attributes. The response message SHALL
therefore return first the matching Node object, then the requested
attributes of the one Portal object that can be used to access the
Storage Node (as indicated by the PGT), and finally the requested
attributes of the PG object used to access that Storage Node. The
order in which each object's attributes are listed is the same as the
ordering of the object's attributes in the Operating Attributes of
the original request message.
If the Message Key Attribute contains zero-length TLV(s), then the
query returns requested attributes for all objects matching the
Message Key type (DD restrictions SHALL apply for non-Control Nodes).
If multiple objects match the Message Key type, then the attributes
for each object matching the Message Key MUST be listed before the
attributes for the next matching object are listed in the query
Tseng, et al. Standards Track [Page 48]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
response. In other words, the process described above must be
iterated in the message response for each object that matches the
Message Key type specified by the zero-length TLV(s).
For example, an iSNS database contains only one Network Entity having
two Portals and three Nodes. All PG objects in the Entity have a PGT
value of 0x00000001. In the DevAttrQry message, the Message Key
contains a zero-length TLV specifying a Node type, and Operating
Attributes listing first the Node attributes, and then the Portal
attributes. The response message will return, in the following
order, the attributes for the first, next, and last Node objects,
each followed by attributes for both Portals. If that same
DevAttrQry message had instead contained a zero-length TLV specifying
the Network Entity type, then the response message would have
returned attributes for all three Node objects, followed by
attributes for the two Portals.
If there is no Message Key Attribute, then the query returns all
attributes in the iSNS database (once again, DD restrictions SHALL
apply for non-Control Nodes). All attributes matching the type
specified by each zero-length TLV in the Operating Attributes SHALL
be listed. All attributes of each type SHALL be listed before the
attributes matching the next zero-length TLV are listed.
For example, an iSNS database contains two Entities, each having two
Nodes and two Portals. The DevAttrQry message contains no Message
Key attribute, and Operating Attributes list first the Portal
attributes, and then the Node attributes. The Operating Attributes
of the response message will return attributes from each of the four
Portals, followed by attributes from each of the four nodes.
If a DevAttrQry message requests an attribute for which the iSNS
server has no value, then the server SHALL NOT return the requested
attribute in the query response. Such query and response messages
SHALL NOT be considered errors.
Registration and query messages for iSNS server-specific attributes
(i.e., tags in the range 132 to 384) SHALL be formatted using the
identifying key attribute of the Storage Node originating the query
(i.e., iSCSI Name or FC Port Name WWPN) for both the Source Attribute
and Message Key attribute. Operating Attributes SHALL include the
TLV of the server-specific attribute being requested.
DD membership can be discovered through the DevAttrQry message by
including either DD member attributes (i.e., DD Member iSCSI Index,
DD Member iSCSI Node, DD Member iFCP Node, DD Member Portal Index, DD
Member Portal IP Addr, and DD Member Portal TCP/UDP) or the object
key of the Storage Node or Portal (i.e., iSCSI Name, iSCSI Index,
Tseng, et al. Standards Track [Page 49]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Portal IP Addr, Portal TCP/UDP Port, and Portal Index) in the
Operating Attributes. Using DD member attributes SHALL return both
registered and unregistered member Storage Nodes and/or Portals of a
DD. DevAttrQry messages using the Storage Node and/or Portal object
key SHALL return only member Storage Nodes or Portals that are
currently registered in the iSNS database.
The DevAttrQry message SHALL support the following minimum set of
Message Key Attributes:
Valid Message Key Attributes for Queries
----------------------------------------
Entity Identifier
Entity Protocol
Portal IP-Address & Portal TCP/UDP Port
Portal Index
iSCSI Node Type
iSCSI Name
iSCSI Index
PG Index
FC Port Name WWPN
FC Port Type
FC-4 Type
Discovery Domain ID
Discovery Domain Set ID
Source Attribute (for server-specific attributes)
Switch Name (FC Device WWNN--for Virtual_Fabric_ID queries)
5.6.5.3. Device Get Next Request (DevGetNext)
The DevGetNext message type is 0x0003. This message provides the
iSNS client with the means to retrieve each and every instance of an
object type exactly once.
The Source Attribute identifies the Node initiating the DevGetNext
request, and is used to scope the retrieval process to the Discovery
Domains of which the initiating Node is a member.
The Message Key Attribute may be an Entity Identifier (EID), iSCSI
Name, iSCSI Index, Portal IP Address and TCP/UDP Port, Portal Index,
PG Index, FC Node Name WWNN, or FC Port Name WWPN. If the TLV length
of the Message Key Attribute(s) is zero, then the first object entry
in the iSNS database matching the Message Key type SHALL be returned
in the Message Key of the corresponding DevGetNextRsp message. If
non-zero-length TLV attributes are contained in the Message Key, then
the DevGetNext response message SHALL return the next object stored
after the object identified by the Message Key in the original
DevGetNext request message.
Tseng, et al. Standards Track [Page 50]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
If the Message Key provided matches the last object instance in the
iSNS database, then the Status Code of 9 (No Such Entry) SHALL be
returned in the response.
The Operating Attributes can be used to specify the scope of the
DevGetNext request, and to specify the attributes of the next object,
which are to be returned in the DevGetNext response message. All
Operating Attributes MUST be attributes of the object type identified
by the Message Key. For example, if the Message Key is an Entity_ID
attribute, then the Operating Attributes MUST NOT contain attributes
of Portals.
Non-zero-length TLV attributes in the Operating Attributes are used
to scope the DevGetNext message. Only the next object with attribute
values that match the non-zero-length TLV attributes SHALL be
returned in the DevGetNext response message.
Zero-length TLV attributes MUST be listed after non-zero-length
attributes in the Operating Attributes of the DevGetNext request
message. Zero-length TLV attributes specify the attributes of the
next object which are to be returned in the DevGetNext response
message.
Note that there are no specific requirements concerning the order in
which object entries are retrieved from the iSNS database; the
retrieval order of object entries using the DevGetNext message is
implementation specific.
The iSNS client is responsible for ensuring that information acquired
through use of the DevGetNext message is accurate and up-to-date.
There is no assurance that the iSNS database will not change between
successive DevGetNext request messages. If the Message Key provided
does not match an existing database entry, then attributes for the
next object key following the provided Message Key SHALL be returned.
For example, an object entry may have been deleted between successive
DevGetNext messages. This may result in a DevGetNext request in
which the Message Key does not match an existing object entry. In
this case, attributes for the next object stored in the iSNS database
are returned.
5.6.5.4. Device Deregister Request (DevDereg)
The DevDereg message type is 0x0004. This message is used to remove
object entries from the iSNS database. One or more objects may be
removed through a single DevDereg message. Note that deregistered
Storage Node objects will retain membership in their Discovery
Domain(s) until explicit deregistration of the membership(s) or
Discovery Domain(s).
Tseng, et al. Standards Track [Page 51]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Upon receiving the DevDereg, the iSNS server removes all objects
identified by the Operating Attribute(s), and all subordinate objects
that are solely dependent on those identified objects. For example,
removal of a Network Entity also results in removal of all associated
Portal, Portal Group, Storage Node, and FC Device objects associated
with that Network Entity. FC Device objects SHALL not be
deregistered in this manner unless all Storage Nodes associated with
them have been deregistered.
The DevDereg request PDU Payload contains a Source Attribute and
Operating Attribute(s); there are no Message Key Attributes. If the
Node identified by the Source Attribute is not a Control Node, then
it MUST be from the same Network Entity as the object(s) identified
for removal by the Operating Attribute(s). Valid Operating
Attributes are shown below:
Valid Operating Attributes for DevDereg
---------------------------------------
Entity Identifier
Portal IP-Address & Portal TCP/UDP Port
Portal Index
iSCSI Name
iSCSI Index
FC Port Name WWPN
FC Node Name WWNN
The removal of the object may result in SCN messages to the
appropriate iSNS clients.
Attempted deregistration of non-existing entries SHALL not be
considered an error.
If all Nodes and Portals associated with a Network Entity are
deregistered, then the Network Entity SHALL also be removed.
If both the Portal and iSCSI Storage Node objects associated with a
Portal Group object are removed, then that Portal Group object SHALL
also be removed. The Portal Group object SHALL remain registered as
long as either of its associated Portal or iSCSI Storage Node objects
remain registered. If a deleted Storage Node or Portal object is
subsequently re-registered, then a relationship between the re-
registered object and an existing Portal or Storage Node object
registration, indicated by the PG object, SHALL be restored.
Tseng, et al. Standards Track [Page 52]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.6.5.5. SCN Register Request (SCNReg)
The SCNReg message type is 0x0005. The State Change Notification
Registration Request (SCNReg) message allows an iSNS client to
register a Storage Node to receive State Change Notification (SCN)
messages.
The SCN notifies the Storage Node of changes to any Storage Nodes
within any DD of which it is a member. If the Storage Node is a
Control Node, it SHALL receive SCN notifications for changes in the
entire network. Note that whereas SCNReg sets the SCN Bitmap field,
the DevAttrReg message registers the UDP or TCP Port used by each
Portal to receive SCN messages. If no SCN Port fields of any Portals
of the Storage Node are registered to receive SCN messages, then the
SCNReg message SHALL be rejected with Status Code 17 (SCN
Registration Rejected).
The SCNReg request PDU Payload contains a Source Attribute, a Message
Key Attribute, and an Operating Attribute. Valid Message Key
Attributes for a SCNReg are shown below:
Valid Message Key Attributes for SCNReg
---------------------------------------
iSCSI Name
FC Port Name WWPN
The node with the iSCSI Name or FC Port Name WWPN attribute that
matches the Message Key in the SCNReg message is registered to
receive SCNs using the specified SCN bitmap. A maximum of one Node
SHALL be registered for each SCNReg message.
The SCN Bitmap is the only operating attribute of this message, and
it always overwrites the previous contents of this field in the iSNS
database. The bitmap indicates the SCN event types for which the
Node is registering.
Note that the settings of this bitmap determine whether the SCN
registration is for regular SCNs or management SCNs. Control Nodes
MAY conduct registrations for management SCNs; iSNS clients that are
not supporting Control Nodes MUST NOT conduct registrations for
management SCNs. Control Nodes that register for management SCNs
receive a copy of every SCN message generated by the iSNS server. It
is recommended that management registrations be used only when needed
in order to conserve iSNS server resources. In addition, a Control
Node that conducts such registrations should be prepared to receive
the anticipated volume of SCN message traffic.
Tseng, et al. Standards Track [Page 53]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.6.5.6. SCN Deregister Request (SCNDereg)
The SCNDereg message type is 0x0006. The SCNDereg message allows an
iSNS client to stop receiving State Change Notification (SCN)
messages.
The SCNDereg request message PDU Payload contains a Source Attribute
and Message Key Attribute(s). Valid Message Key Attributes for a
SCNDereg are shown below:
Valid Message Key Attributes for SCNDereg
-----------------------------------------
iSCSI Name
FC Port Name WWPN
The node with an iSCSI Name or FC Port Name WWPN attribute that
matches the Message Key Attributes in the SCNDereg message is
deregistered for SCNs. The SCN bitmap field of such Nodes are
cleared. A maximum of one Node SHALL be deregistered for each
SCNDereg message.
There are no Operating Attributes in the SCNDereg message.
5.6.5.7. SCN Event (SCNEvent)
The SCNEvent message type is 0x0007. The SCNEvent is a message sent
by an iSNS client to request generation of a State Change
Notification (SCN) message by the iSNS server. The SCN, sent by the
iSNS server, then notifies iFCP, iSCSI, and Control Nodes within the
affected DD of the change indicated in the SCNEvent.
Most SCNs are automatically generated by the iSNS server when Nodes
are registered or deregistered from the directory database. SCNs are
also generated when a network management application or Control Node
makes changes to the DD membership in the iSNS server. However, an
iSNS client can trigger an SCN by using SCNEvent.
The SCNEvent message PDU Payload contains a Source Attribute, a
Message Key Attribute, and an Operating Attribute. Valid Key
Attributes for a SCNEvent are shown below:
Valid Message Key Attributes for SCNEvent
-----------------------------------------
iSCSI Name
FC Port Name WWPN
Tseng, et al. Standards Track [Page 54]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
The Operating Attributes section SHALL contain the SCN Event Bitmap
attribute. The bitmap indicates the event that caused the SCNEvent
to be generated.
5.6.5.8. State Change Notification (SCN)
The SCN message type is 0x0008. The SCN is a message generated by
the iSNS server, notifying a registered Storage Node of changes.
There are two types of SCN registrations: regular registrations and
management registrations. Regular SCNs notify iSNS clients of events
within the discovery domain. Management SCNs notify Control Nodes
that register for management SCNs of events occurring anywhere in the
network.
If no active TCP connection to the SCN recipient exists, then the SCN
message SHALL be sent to one Portal of the registered Storage Node
that has a registered TCP or UDP Port value in the SCN Port field.
If more than one Portal of the Storage Node has a registered SCN Port
value, then the SCN SHALL be delivered to any one of the indicated
Portals, provided that the selected Portal is not the subject of the
SCN.
The types of events that can trigger an SCN message, and the amount
of information contained in the SCN message, depend on the registered
SCN Event Bitmap for the Storage Node. The iSCSI Node SCN Bitmap is
described in Section 6.4.4. The iFCP SCN Bitmap is described in
Section 6.6.12.
Tseng, et al. Standards Track [Page 55]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
The format of the SCN PDU Payload is shown below:
+----------------------------------------+
| Destination Attribute |
+----------------------------------------+
| Timestamp |
+----------------------------------------+
| Source SCN Bitmap 1 |
+----------------------------------------+
| Source Attribute [1] |
+----------------------------------------+
| Source Attribute [2](if present) |
+----------------------------------------+
| Source Attribute [3](if present) |
+----------------------------------------+
| Source Attribute [n](if present) |
+----------------------------------------+
| Source SCN Bitmap 2 (if present) |
+----------------------------------------+
| . . . |
+----------------------------------------+
All PDU Payload attributes are in TLV format.
The Destination Attribute is the Node identifier that is receiving
the SCN. The Destination Attribute can be an iSCSI Name or FC Port
Name.
The Timestamp field, using the Timestamp TLV format, described in
Section 6.2.4, indicates the time the SCN was generated.
The Source SCN Bitmap field indicates the type of SCN notification
(i.e., regular or management SCN), and the type of event that caused
the SCN to be generated; it does not necessarily correlate with the
original SCN bitmap registered in the iSNS server.
Following the timestamp, the SCN message SHALL list the SCN bitmap,
followed by the key attribute (i.e., iSCSI Name or FC Port Name) of
the Storage Node affected by the SCN event. If the SCN is a
Management SCN, then the SCN message SHALL also list the DD_ID and/or
DDS_ID of the Discovery Domains and Discovery Domain Sets (if any)
that caused the change in state for that Storage Node. These
additional attributes (i.e., DD_ID and/or DDS_ID) shall immediately
follow the iSCSI Name or FC Port Name and precede the next SCN bitmap
for the next notification message (if any). The SCN bitmap is used
as a delineator for SCN messages providing multiple state change
notifications.
Tseng, et al. Standards Track [Page 56]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
For example, a regular SCN for notifying an iSNS client of a new
Portal available for a particular iSCSI target would contain the SCN
bitmap followed by the iSCSI Name of the target device as the source
attribute. If the SCN were a management SCN, then the iSCSI Name
would be followed by the DD_ID(s) of the shared Discovery Domains
that allow the destination Storage Node to have visibility to the
affected Storage Node. If a Discovery Domain Set (DDS) was enabled
in order to provide this visibility, then the appropriate DDS_ID
would be included as well.
A management SCN is also generated to notify a Control Node of the
creation, deletion, or modification of a Discovery Domain or
Discovery Domain Set. In this case, the DD_ID and/or DDS_ID of the
affected Discovery Domain and/or Discovery Domain Set would follow
the SCN bitmap.
For example, a management SCN to notify a Control Node of a new DD
within a Discovery Domain Set would contain both the DD_ID and the
DDS_ID of the affected Discovery Domain and Discovery Domain Set
among the Source Attributes.
See Sections 6.4.4 and 6.6.12 for additional information on the SCN
Bitmap.
5.6.5.9. DD Register (DDReg)
The DDReg message type is 0x0009. This message is used to create a
new Discovery Domain (DD), to update an existing DD Symbolic Name
and/or DD Features attribute, and to add DD members.
DDs are uniquely defined using DD_IDs. DD registration attributes
are described in Section 6.11.
The DDReg message PDU Payload contains the Source Attribute and
optional Message Key and Operating Attributes.
The Message Key, if used, contains the DD_ID of the Discovery Domain
to be registered. If the Message Key contains a DD_ID of an existing
DD entry in the iSNS database, then the DDReg message SHALL attempt
to update the existing entry. If the DD_ID in the Message Key (if
used) does not match an existing DD entry, then the iSNS server SHALL
reject the DDReg message with a status code of 3 (Invalid
Registration). If the DD_ID is included in both the Message Key and
Operating Attributes, then the DD_ID value in the Message Key MUST be
the same as the DD_ID value in the Operating Attributes.
Tseng, et al. Standards Track [Page 57]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
A DDReg message with no Message Key SHALL result in the attempted
creation of a new Discovery Domain (DD). If the DD_ID attribute
(with non-zero length) is included among the Operating Attributes in
the DDReg message, then the new Discovery Domain SHALL be assigned
the value contained in that DD_ID attribute. Otherwise, if the DD_ID
attribute is not contained among the Operating Attributes of the
DDReg message, or if the DD_ID is an operating attribute with a TLV
length of 0, then the iSNS server SHALL assign a DD_ID value. The
assigned DD_ID value is then returned in the DDReg Response message.
The Operating Attributes can also contain the DD Member iSCSI Node
Index, DD Member iSCSI Name, DD Member FC Port Name, DD Member Portal
IP Address, DD Member Portal TCP/UDP Port Number, or DD Member Portal
Index of members to be added to the DD. It may also contain the
DD_Symbolic_Name and/or DD_Features of the DD.
This message SHALL add any DD members listed as Operating Attributes
to the Discovery Domain specified by the DD_ID. If the DD_Features
attribute is an Operating Attribute, then it SHALL be stored in the
iSNS server as the feature list for the specified DD. If the
DD_Symbolic_Name is an operating attribute and its value is unique
(i.e., it does not match the registered DD_Symbolic_Name for another
DD), then the value SHALL be stored in the iSNS database as the
DD_Symbolic_Name for the specified Discovery Domain. If the value
for the DD_Symbolic_Name is not unique, then the iSNS server SHALL
reject the attempted DD registration with a status code of 3 (Invalid
Registration).
When creating a new DD, if the DD_Symbolic_Name is not included in
the Operating Attributes, or if it is included with a zero-length
TLV, then the iSNS server SHALL provide a unique DD_Symbolic_Name
value for the created DD. The assigned DD_Symbolic_Name value SHALL
be returned in the DDRegRsp message.
When creating a new DD, if the DD_Features attribute is not included
in the Operating Attributes, then the iSNS server SHALL assign the
default value. The default value for DD_Features is 0.
DD Member iSCSI Name, DD Member iFCP Node, DD Member Portal IP
Address, and DD Member TCP/UDP Port Number attributes included in the
Operating Attributes need not match currently existing iSNS database
entries. This allows, for example, a Storage Node to be added to a
DD even if the Storage Node is not currently registered in the iSNS
database. A Storage Node or Portal can thereby be added to a DD at
the time of the DDs creation, even if the Storage Node or Portal is
not currently active in the storage network.
Tseng, et al. Standards Track [Page 58]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
If the Operating Attributes contain a DD Member iSCSI Name value for
a Storage Node that is currently not registered in the iSNS database,
then the iSNS server MUST allocate an unused iSCSI Node Index for
that Storage Node. The assigned iSCSI Node Index SHALL be returned
in the DDRegRsp message as the DD Member iSCSI Node Index. The
allocated iSCSI Node Index value SHALL be assigned to the Storage
Node if and when it registers in the iSNS database.
If the Operating Attributes contain a DD Member Portal IP Addr and DD
Member Portal TCP/UDP value for a Portal that is not currently
registered in the iSNS database, then the iSNS server MUST allocate
an unused Portal Index value for that Portal. The assigned Portal
Index value SHALL be returned in the DDRegRsp message as the DD
Member Portal Index. The allocated Portal Index value SHALL be
assigned to the Portal if and when it registers in the iSNS database.
DD Member iSCSI Node Index and DD Member Portal Index attributes that
are provided in the Operating Attributes MUST match a corresponding
iSCSI Node Index or Portal Index of an existing Storage Node or
Portal entry in the iSNS database. Furthermore, the DD Member iSCSI
Node Index and DD Member Portal Index SHALL NOT be used to add
Storage Nodes or Portals to a DD unless those Storage Nodes or
Portals are actively registered in the iSNS database.
5.6.5.10. DD Deregister (DDDereg)
The DDDereg message type is 0x000A. This message allows an iSNS
client to deregister an existing Discovery Domain (DD) and to remove
members from an existing DD.
DDs are uniquely identified using DD_IDs. DD registration attributes
are described in Section 6.11.
The DDDereg message PDU Payload contains a Source Attribute, Message
Key Attribute, and optional Operating Attributes.
The Message Key Attribute for a DDDereg message is the DD ID for the
Discovery Domain being removed or having members removed. If the DD
ID matches an existing DD and there are no Operating Attributes, then
the DD SHALL be removed and a success Status Code returned. Any
existing members of that DD SHALL remain in the iSNS database without
membership in the just-removed DD.
If the DD ID matches an existing DD and there are Operating
Attributes matching DD members, then the DD members identified by the
Operating Attributes SHALL be removed from the DD and a successful
Status Code returned.
Tseng, et al. Standards Track [Page 59]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
If a DD Member iSCSI Name identified in the Operating Attributes
contains an iSCSI Name for a Storage Node that is not currently
registered in the iSNS database or contained in another DD, then the
association between that Storage Node and its pre-assigned iSCSI Node
Index SHALL be removed. The pre-assigned iSCSI Node Index value no
longer has an association to a specific iSCSI Name and can now be
re-assigned.
If a DD Member Portal IP Address and DD Member TCP/UDP Port
identified in the Operating Attributes reference a Portal that is not
currently registered in the iSNS database or contained in another DD,
then the association between that Portal and its pre-assigned Portal
Index SHALL be removed. The pre-assigned Portal Index value can now
be reassigned.
The attempted deregistration of non-existent DD entries SHALL not be
considered an error.
5.6.5.11. DDS Register (DDSReg)
The DDSReg message type is 0x000B. This message allows an iSNS
client to create a new Discovery Domain Set (DDS), to update an
existing DDS Symbolic Name and/or DDS Status, or to add DDS members.
DDSs are uniquely defined using DDS_IDs. DDS registration attributes
are described in Section 6.11.1.
The DDSReg message PDU Payload contains the Source Attribute and,
optionally, Message Key and Operating Attributes.
The Message Key, if used, contains the DDS_ID of the Discover Domain
Set to be registered or modified. If the Message Key contains a
DDS_ID of an existing DDS entry in the iSNS database, then the DDSReg
message SHALL attempt to update the existing entry. If the DDS_ID in
the Message Key (if used) does not match an existing DDS entry, then
the iSNS server SHALL reject the DDSReg message with a status code of
3 (Invalid Registration). If the DDS_ID is included in both the
Message Key and Operating Attributes, then the DDS_ID value in the
Message Key MUST be the same as the DDS_ID value in the Operating
Attributes.
A DDSReg message with no Message Key SHALL result in the attempted
creation of a new Discovery Domain Set (DDS). If the DDS_ID
attribute (with non-zero length) is included among the Operating
Attributes in the DDSReg message, then the new Discovery Domain Set
SHALL be assigned the value contained in that DDS_ID attribute.
Otherwise, if the DDS_ID attribute is not contained among the
Operating Attributes of the DDSReg message, or if the DDS_ID is an
Tseng, et al. Standards Track [Page 60]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
operating attribute with a TLV length of 0, then the iSNS server
SHALL assign a DDS_ID value. The assigned DDS_ID value is then
returned in the DDSReg Response message. The Operating Attributes
can also contain the DDS_Symbolic_Name, the DDS Status, and the
DD_IDs of Discovery Domains to be added to the DDS.
When creating a new DDS, if the DDS Symbolic Name is included in the
Operating Attributes and its value is unique (i.e., it does not match
the registered DDS Symbolic Name for another DDS), then the value
SHALL be stored in the iSNS database as the DDS Symbolic Name for
that DDS. If the value for the DDS Symbolic Name is not unique, then
the iSNS server SHALL reject the attempted DDS registration with a
status code of 3 (Invalid Registration).
When creating a new DDS, if the DDS Symbolic Name is not included in
the Operating Attributes, or if it is included with a zero-length
TLV, then the iSNS server SHALL provide a unique DDS Symbolic Name
value for the created DDS. The assigned DDS Symbolic Name value
SHALL be returned in the DDSRegRsp message.
This message SHALL add any DD_IDs listed as Operating Attributes to
the Discovery Domain Set specified by the DDS_ID Message Key
Attribute. In addition, if the DDS_Symbolic_Name is an operating
attribute and the value is unique, then it SHALL be stored in the
iSNS database as the DDS_Symbolic_Name for the specified Discovery
Domain Set.
If a DD_ID listed in the Operating Attributes does not match an
existing DD, then a new DD using the DD_ID SHALL be created. In this
case for the new DD, the iSNS server SHALL assign a unique value for
the DD Symbolic Name and SHALL set the DD Features attribute to the
default value of 0. These assigned values SHALL be returned in the
DDSRegRsp message.
5.6.5.12. DDS Deregister (DDSDereg)
The DDSDereg message type is 0x000C. This message allows an iSNS
client to deregister an existing Discovery Domain Set (DDS) or to
remove some DDs from an existing DDS.
The DDSDereg message PDU Payload contains a Source Attribute, a
Message Key Attribute, and optional Operating Attributes.
The Message Key Attribute for a DDSDereg message is the DDS ID for
the DDS being removed or having members removed. If the DDS ID
matches an existing DDS and there are no Operating Attributes, then
Tseng, et al. Standards Track [Page 61]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
the DDS SHALL be removed and a success Status Code returned. Any
existing members of that DDS SHALL remain in the iSNS database
without membership in the just-removed DDS.
If the DDS ID matches an existing DDS, and there are Operating
Attributes matching DDS members, then the DDS members SHALL be
removed from the DDS and a success Status Code returned.
The attempted deregistration of non-existent DDS entries SHALL not be
considered an error.
5.6.5.13. Entity Status Inquiry (ESI)
The ESI message type is 0x000D. This message is sent by the iSNS
server, and is used to verify that an iSNS client Portal is reachable
and available. The ESI message is sent to the ESI UDP port provided
during registration, or to the TCP connection used for ESI
registration, depending on which communication type that is being
used.
The ESI message PDU Payload contains the following attributes in TLV
format and in the order listed: the current iSNS timestamp, the EID,
the Portal IP Address, and the Portal TCP/UDP Port. The format of
this message is shown below:
+----------------------------------------+
| Timestamp |
+----------------------------------------+
| Entity_ID |
+----------------------------------------+
| Portal IP Address |
+----------------------------------------+
| Portal TCP/UDP Port |
+----------------------------------------+
The ESI response message PDU Payload contains a status code, followed
by the Attributes from the original ESI message.
If the Portal fails to respond to an administratively-determined
number of consecutive ESI messages, then the iSNS server SHALL remove
that Portal from the iSNS database. If there are no other remaining
ESI-monitored Portals for the associated Network Entity, then the
Network Entity SHALL also be removed. The appropriate State Change
Notifications, if any, SHALL be triggered.
Tseng, et al. Standards Track [Page 62]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.6.5.14. Name Service Heartbeat (Heartbeat)
This message, if used, is only sent by the active iSNS server. It
allows iSNS clients and backup servers listening to a broadcast or
multicast address to discover the IP address of the primary and
backup iSNS servers. It also allows concerned parties to monitor the
health and status of the primary iSNS server.
This message is NOT in TLV format. There is no response message to
the Name Service Heartbeat.
MSb LSb
0 31
+------------------------------------------------+
| Active Server IP-Address | 16 Bytes
+------------------------------------------------+
| iSNS TCP Port | iSNS UDP Port | 4 Bytes
+------------------------------------------------+
| Interval | 4 Bytes
+------------------------------------------------+
| Counter | 4 Bytes
+------------------------------------------------+
| RESERVED | Backup Servers | 4 Bytes
+------------------------------------------------+
| Primary Backup Server IP Address(if any) | 16 Bytes
+------------------------------------------------+
|Backup TCP Port(if any)|Backup UDP Port(if any) | 4 Bytes
+------------------------------------------------+
| 2nd Backup Server IP Address(if any) | 16 Bytes
+------------------------------------------------+
|Backup TCP Port(if any)|Backup UDP Port(if any) | 4 Bytes
+------------------------------------------------+
| . . . |
+------------------------------------------------+
| VENDOR SPECIFIC |
+------------------------------------------------+
The heartbeat PDU Payload contains the following:
Active Server IP Address: the IP Address of the active iSNS server in
IPv6 format. When this field contains an IPv4
value, it is stored as an IPv4-mapped IPv6 address.
That is, the most significant 10 bytes are set to
0x00, with the next two bytes set to 0xFFFF
[RFC2373]. When this field contains an IPv6 value,
the entire 16-byte field is used.
Active TCP Port: the TCP Port of the server currently in use.
Tseng, et al. Standards Track [Page 63]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Active UDP Port: the UDP Port of the server currently in use,
otherwise 0.
Interval: the interval, in seconds, of the heartbeat.
Counter: a count that begins at 0 when this server becomes
active. The count increments by one for each
heartbeat sent since this server became active.
Backup Servers: the number of iSNS backup servers. The IP address,
TCP Port, and UDP Port of each iSNS backup server
follow this field. Note that if backup servers are
used, then the active iSNS server SHOULD be among
the list of backup servers.
The content of the remainder of this message after the list of backup
servers is vendor-specific. Vendors may use additional fields to
coordinate between multiple iSNS servers, and/or to identify vendor-
specific features.
5.6.5.15. Request FC_DOMAIN_ID (RqstDomId)
The RqstDomId message type is 0x0011. This message is used for iFCP
Transparent Mode to allocate non-overlapping FC_DOMAIN_ID values
between 1 and 239. The iSNS server becomes the address assignment
authority for the entire iFCP fabric. To obtain multiple
FC_DOMAIN_ID values, this request must be repeated to the iSNS server
multiple times. iSNS clients that acquire FC_DOMAIN_ID values from
an iSNS server MUST register for ESI monitoring from that iSNS
server.
The RqstDomId PDU Payload contains three TLV attributes in the
following order: the requesting Switch Name (WWN) as the Source
Attribute, the Virtual_Fabric_ID as the Message Key Attribute, and
Preferred ID as the operating attribute. The Virtual_Fabric_ID is a
string identifying the domain space for which the iSNS server SHALL
allocate non-overlapping integer FC_DOMAIN_ID values between 1 and
239. The Preferred_ID is the nominal FC_DOMAIN_ID value requested by
the iSNS client. If the Preferred_ID value is available and has not
already been allocated for the Virtual_Fabric_ID specified in the
message, the iSNS server SHALL return the requested Preferred_ID
value as the Assigned_ID to the requesting client.
The RqstDomId response contains a Status Code, and the TLV attribute
Assigned ID, which contains the integer value in the space requested.
If no further unallocated values are available from this space, the
iSNS server SHALL respond with the Status Code 18 "FC_DOMAIN_ID Not
Available".
Tseng, et al. Standards Track [Page 64]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Once a FC_DOMAIN_ID value has been allocated to an iSNS client by the
iSNS server for a given Virtual_Fabric_ID, that FC_DOMAIN_ID value
SHALL NOT be reused until it has been deallocated, or until ESI
monitoring detects that the iSNS client no longer exists on the
network and objects for that client are removed from the iSNS
database.
The iSNS server and client SHALL use TCP to transmit and receive
RqstDomId, RqstDomIdRsp, RlseDomId, and RlseDomIdRsp messages.
5.6.5.16. Release FC_DOMAIN_ID (RlseDomId)
The RlseDomId message type is 0x0012. This message may be used by
iFCP Transparent Mode to release integer identifier values used to
assign 3-byte Fibre Channel PORT_ID values.
The RlseDomId message contains three TLV attributes in the following
order: the requesting EID as the Source Attribute, the
Virtual_Fabric_ID as the Message Key Attribute, and Assigned_ID as
the operating attribute. Upon receiving the RlseDomId message, the
iSNS server SHALL deallocate the FC_DOMAIN_ID value contained in the
Assigned_ID attribute for the Virtual_Fabric_ID attribute specified.
Upon deallocation, that FC_DOMAIN_ID value can then be requested by
and assigned to a different iSNS client.
The iSNS server and client SHALL use TCP to transmit and receive
RqstDomId, RqstDomIdRsp, RlseDomId, and RlseDomIdRsp messages.
5.6.5.17. Get FC_DOMAIN_IDs (GetDomId)
The GetDomId message type is 0x0013. This message is used to learn
the currently-allocated FC_DOMAIN_ID values for a given
Virtual_Fabric_ID.
The GetDomId message PDU Payload contains a Source Attribute and
Message Key Attribute.
The Message Key Attribute for the GetDomId message is the
Virtual_Fabric_ID. The response to this message returns all the
FC_DOMAIN_ID values that have been allocated for the
Virtual_Fabric_ID specified.
Tseng, et al. Standards Track [Page 65]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.7. Messages
The iSNSP response message PDU Payloads contain a Status Code,
followed by a list of attributes, and have the following format:
MSb LSb
0 31
+----------------------------------------+
| 4-byte STATUS CODE |
+----------------------------------------+
| Message Key Attribute[1] (if present) |
+----------------------------------------+
| Message Key Attribute[2] (if present) |
+----------------------------------------+
| . . . |
+----------------------------------------+
| - Delimiter Attribute - (if present) |
+----------------------------------------+
| Operating Attribute[1] (if present) |
+----------------------------------------+
| Operating Attribute[2] (if present) |
+----------------------------------------+
| Operating Attribute[3] (if present) |
+----------------------------------------+
| . . . |
+----------------------------------------+
The iSNSP Response messages SHALL be sent to the iSNS Client IP
Address and the originating TCP/UDP Port that was used for the
associated registration and query message.
5.7.1. Status Code
The first field in an iSNSP response message PDU Payload is the
Status Code for the operation that was performed. The Status Code
encoding is defined in Section 5.4.
5.7.2. Message Key Attributes in Response
Depending on the specific iSNSP request, the response message MAY
contain Message Key Attributes. Message Key Attributes generally
contain the interesting key attributes that are affected by the
operation specified in the original iSNS registration or query
message.
Tseng, et al. Standards Track [Page 66]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.7.3. Delimiter Attribute in Response
The Delimiter Attribute separates the key and Operating Attributes in
a response message, if they exist. The Delimiter Attribute has a tag
value of 0 and a length value of 0. The Delimiter Attribute is
effectively 8 bytes long: a 4-byte tag containing 0x00000000, and a 4
Byte length field containing 0x00000000.
5.7.4. Operating Attributes in Response
The Operating Attributes in a response are the results related to the
iSNS registration or query operation being performed. Some response
messages will not have Operating Attributes.
5.7.5. Registration and Query Response Message Types
The following sections describe each query and message type.
5.7.5.1. Device Attribute Registration Response (DevAttrRegRsp)
The DevAttrRegRsp message type is 0x8001. The DevAttrRegRsp message
contains the results for the DevAttrReg message with the same
TRANSACTION ID.
The Message Key in the DevAttrRegRsp message SHALL return the Message
Key in the original registration message. If the iSNS server
assigned the Entity Identifier for a Network Entity, then the Message
Key Attribute field SHALL contain the assigned Entity Identifier.
The Operating Attributes of the DevAttrRegRsp message SHALL contain
the affected object's key and non-key attributes that have been
explicitly modified or created by the original DevAttrReg message.
Among the Operating Attributes, each modified or added non-key
attribute SHALL be listed after its key attribute(s) in the
DevAttrRegRsp message. Implicitly registered attributes MUST NOT be
returned in the DevAttrRegRsp message. Implicitly registered
attributes are those that are assigned a fixed default value or
secondary index value by the iSNS server.
Implicitly registered PG objects (i.e., PG objects that are not
explicitly included in the registration or replace message) MUST NOT
have their key or non-key attributes returned in the DevAttrRegRsp
message. However, explicitly registered PG objects (i.e., those with
PGT values that are explicitly included in the registration or
replace message) SHALL have their PGT values returned in the
DevAttrRegRsp message.
Tseng, et al. Standards Track [Page 67]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
For example, three Portals are registered in the original DevAttrReg
request message. Due to lack of resources, the iSNS server needs to
modify the registered ESI Interval value of one of those Portals. To
accomplish this, the iSNS server returns the key attributes
identifying the Portal, followed by the non-key modified ESI Interval
attribute value, as Operating Attributes of the corresponding
DevAttrRegRsp message.
If the iSNS server rejects a registration due to invalid attribute
values or types, then the indicated status code SHALL be 3 (Invalid
Registration). If this occurs, then the iSNS server MAY include the
list of invalid attributes in the Operating Attributes of the
DevAttrRsp message.
Some attributes values (e.g., ESI Interval, Registration Period) in
the original registration message MAY be modified by the iSNS server.
This can occur only for a limited set of attribute types, as
indicated in the table in Section 6.1. When this occurs, the
registration SHALL be considered a success (with status code 0), and
the changed value(s) indicated in the Operating Attributes of the
DevAttrRsp message.
5.7.5.2. Device Attribute Query Response (DevAttrQryRsp)
The DevAttrQryRsp message type is 0x8002. The DevAttrQryRsp message
contains the results for the DevAttrQry message with the same
TRANSACTION ID.
The Message Key in the DevAttrQryRsp message SHALL return the Message
Key in the original query message.
If no Operating Attributes are included in the original query, then
all Operating Attributes SHALL be returned in the response.
For a successful query result, the DevAttrQryRsp Operating Attributes
SHALL contain the results of the original DevAttrQry message.
5.7.5.3. Device Get Next Response (DevGetNextRsp)
The DevGetNextRsp message type is 0x8003. The DevGetNextRsp message
contains the results for the DevGetNext message with the same
TRANSACTION ID.
The Message Key Attribute field returns the object keys for the next
object after the Message Key Attribute in the original DevGetNext
message.
Tseng, et al. Standards Track [Page 68]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
The Operating Attribute field returns the Operating Attributes of the
next object as requested in the original DevGetNext message. The
values of the Operating Attributes are those associated with the
object identified by the Message Key Attribute field of the
DevGetNextRsp message.
5.7.5.4. Deregister Device Response (DevDeregRsp)
The DevDeregRsp message type is 0x8004. This message is the response
to the DevDereg request message.
This message response does not contain a Message Key, but MAY contain
Operating Attributes.
In the event of an error, this response message contains the
appropriate status code as well as a list of objects from the
original DevDereg message that were not successfully deregistered
from the iSNS database. This list of objects is contained in the
Operating Attributes of the DevDeregRsp message. Note that an
attempted deregistration of a non-existent object does not constitute
an error, and non-existent entries SHALL not be returned in the
DevDeregRsp message.
5.7.5.5. SCN Register Response (SCNRegRsp)
The SCNRegRsp message type is 0x8005. This message is the response
to the SCNReg request message.
The SCNRegRsp message does not contain any Message Key or Operating
Attributes.
5.7.5.6. SCN Deregister Response (SCNDeregRsp)
The SCNDeregRsp message type is 0x8006. This message is the response
to the SCNDereg request message.
The SCNDeregRsp message does not contain any Message Key or Operating
Attributes.
5.7.5.7. SCN Event Response (SCNEventRsp)
The SCNEventRsp message type is 0x8007. This message is the response
to the SCNEvent request message.
The SCNEventRsp message does not contain any Message Key or Operating
Attributes.
Tseng, et al. Standards Track [Page 69]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.7.5.8. SCN Response (SCNRsp)
The SCNRsp message type is 0x8008. This message is sent by an iSNS
client, and provides confirmation that the SCN message was received
and processed.
The SCNRsp response contains the SCN Destination Attribute
representing the Node identifier that received the SCN.
5.7.5.9. DD Register Response (DDRegRsp)
The DDRegRsp message type is 0x8009. This message is the response to
the DDReg request message.
The Message Key in the DDRegRsp message SHALL return the Message Key
in the original query message. If the original DDReg message did not
have a Message Key, then the DDRegRsp message SHALL not have a
Message Key.
If the DDReg operation is successful, the DD ID of the DD created or
updated SHALL be returned as an operating attribute of the message.
If the DD Symbolic Name attribute or DD Features attribute was
assigned or updated during the DDReg operation, then any new values
SHALL be returned as an operating attribute of the DDRegRsp message.
If the iSNS server rejects a DDReg due to invalid attribute values or
types, then the indicated status code SHALL be 3 (Invalid
Registration). If this occurs, then the iSNS server MAY include the
list of invalid attributes in the Operating Attributes of the
DDRegRsp message.
5.7.5.10. DD Deregister Response (DDDeregRsp)
The DDDeregRsp message type is 0x800A. This message is the response
to the DDDereg request message.
The DDDeregRsp message does not contain any Message Key or Operating
Attributes.
Tseng, et al. Standards Track [Page 70]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.7.5.11. DDS Register Response (DDSRegRsp)
The DDSRegRsp message type is 0x800B. This message is the response
to the DDSReg request message.
The Message Key in the DDSRegRsp message SHALL contain the Message
Key of the original DDSReg message. If the original DDSReg message
did not have a Message Key, then the DDSRegRsp message SHALL NOT have
a Message Key.
If the DDSReg operation is successful, the DDS ID of the DDS created
or updated SHALL be returned as an operating attribute of the
message.
If the DDS Symbolic Name attribute or DDS Status attribute was
assigned or updated during the DDSRegRsp operation, then any new
values SHALL be returned as an operating attribute of the DDSRegRsp
message.
If the iSNS server rejects a DDSReg due to invalid attribute values
or types, then the indicated status code SHALL be 3 (Invalid
Registration). If this occurs, then the iSNS server MAY include the
list of invalid attributes in the Operating Attributes of the
DDSRegRsp message.
5.7.5.12. DDS Deregister Response (DDSDeregRsp)
The DDSDeregRsp message type is 0x800C. This message is the response
to the DDSDereg request message.
The DDSDeregRsp message does not contain any Message Key or Operating
Attributes.
5.7.5.13. Entity Status Inquiry Response (ESIRsp)
The ESIRsp message type is 0x800D. This message is sent by an iSNS
client and provides confirmation that the ESI message was received
and processed.
The ESIRsp response message PDU Payload contains the attributes from
the original ESI message. These attributes represent the Portal that
is responding to the ESI. The ESIRsp Attributes are in the order
they were provided in the original ESI message.
Upon receiving the ESIRsp from the iSNS client, the iSNS server SHALL
update the timestamp attribute for that Network Entity and Portal.
Tseng, et al. Standards Track [Page 71]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
5.7.5.14. Request FC_DOMAIN_ID Response (RqstDomIdRsp)
The RqstDomIdRsp message type is 0x8011. This message provides the
response for RqstDomId.
The RqstDomId response contains a Status Code and the TLV attribute
Assigned ID, which contains the integer value in the space requested.
If no further unallocated values are available from this space, the
iSNS server SHALL respond with the Status Code 19 "FC_DOMAIN_ID Not
Available".
Once a FC_DOMAIN_ID value is allocated by the iSNS server, it SHALL
NOT be reused until it has been deallocated by the iSNS client to
which the value was assigned, or until the ESI message detects that
the iSNS client no longer exists on the network.
The iSNS server and client SHALL use TCP to transmit and receive
RqstDomId, RqstDomIdRsp, RlseDomId, and RlseDomIdRsp messages.
5.7.5.15. Release FC_DOMAIN_ID Response (RlseDomIdRsp)
The RlseDomIdRsp message type is 0x8012. This message provides the
response for RlseDomId. The response contains an Error indicating
whether the request was successful. If the Assigned_ID value in the
original RlseDomId message is not allocated, then the iSNS server
SHALL respond with this message using the Status Code 20
"FC_DOMAIN_ID Not Allocated".
The iSNS server and client SHALL use TCP to transmit and receive
RqstDomId, RqstDomIdRsp, RlseDomId, and RlseDomIdRsp messages.
5.7.5.16. Get FC_DOMAIN_IDs Response (GetDomIdRsp)
The GetDomIdRsp message type is 0x8013. This message is used to
determine which FC_DOMAIN_ID values have been allocated for the
Virtual_Fabric_ID specified in the original GetDomId request message.
The GetDomId response message PDU Payload contains a Status Code
indicating whether the request was successful, and a list of the
Assigned IDs from the space requested. The Assigned_ID attributes
are listed in TLV format.
5.8. Vendor-Specific Messages
Vendor-specific iSNSP messages have a functional ID of between 0x0100
and 0x01FF, whereas vendor-specific responses have a functional ID of
between 0x8100 and 0x81FF. The first Message Key Attribute in a
Tseng, et al. Standards Track [Page 72]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
vendor-specific message SHALL be the company OUI (tag=256)
identifying the original creator of the proprietary iSNSP message.
The contents of the remainder of the message are vendor-specific.
6. iSNS Attributes
Attributes can be stored in the iSNS server using iSNSP registration
messages, and they can be retrieved using iSNSP query messages.
Unless otherwise indicated, these attributes are supplied by iSNS
clients using iSNSP registration messages.
6.1. iSNS Attribute Summary
The complete registry of iSNS attributes is maintained by IANA, and
the following table summarizes the initial set of iSNS attributes
available at the time of publication of this document.
Attributes Length Tag Reg Key Query Key
---------- ------ --- ------- ---------
Delimiter 0 0 N/A N/A
Entity Identifier (EID) 4-256 1 1 1|2|16&17|32|64
Entity Protocol 4 2 1 1|2|16&17|32|64
Management IP Address 16 3 1 1|2|16&17|32|64
Timestamp 8 4 -- 1|2|16&17|32|64
Protocol Version Range 4 5 1 1|2|16&17|32|64
Registration Period 4 6 1 1|2|16&17|32|64
Entity Index 4 7 1 1|2|16&17|32|64
Entity Next Index 4 8 -- 1|2|16&17|32|64
Entity ISAKMP Phase-1 var 11 1 1|2|16&17|32|64
Entity Certificate var 12 1 1|2|16&17|32|64
Portal IP Address 16 16 1 1|16&17|32|64
Portal TCP/UDP Port 4 17 1 1|16&17|32|64
Portal Symbolic Name 4-256 18 16&17 1|16&17|32|64
ESI Interval 4 19 16&17 1|16&17|32|64
ESI Port 4 20 16&17 1|16&17|32|64
Portal Index 4 22 16&17 1|16&17|32|64
SCN Port 4 23 16&17 1|16&17|32|64
Portal Next Index 4 24 -- 1|16&17|32|64
Portal Security Bitmap 4 27 16&17 1|16&17|32|64
Portal ISAKMP Phase-1 var 28 16&17 1|16&17|32|64
Portal ISAKMP Phase-2 var 29 16&17 1|16&17|32|64
Portal Certificate var 31 16&17 1|16&17|32|64
iSCSI Name 4-224 32 1 1|16&17|32|33
iSCSI Node Type 4 33 32 1|16&17|32
iSCSI Alias 4-256 34 32 1|16&17|32
iSCSI SCN Bitmap 4 35 32 1|16&17|32
iSCSI Node Index 4 36 32 1|16&17|32
WWNN Token 8 37 32 1|16&17|32
Tseng, et al. Standards Track [Page 73]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
iSCSI Node Next Index 4 38 -- 1|16&17|32
iSCSI AuthMethod var 42 32 1|16&17|32
PG iSCSI Name 4-224 48 32|16&17 1|16&17|32|52
PG Portal IP Addr 16 49 32|16&17 1|16&17|32|52
PG Portal TCP/UDP Port 4 50 32|16&17 1|16&17|32|52
PG Tag (PGT) 4 51 32|16&17 1|16&17|32|52
PG Index 4 52 32|16&17 1|16&17|32|52
PG Next Index 4 53 -- 1|16&17|32|52
FC Port Name WWPN 8 64 1 1|16&17|64|66|96|128
Port ID 4 65 64 1|16&17|64
FC Port Type 4 66 64 1|16&17|64
Symbolic Port Name 4-256 67 64 1|16&17|64
Fabric Port Name 8 68 64 1|16&17|64
Hard Address 4 69 64 1|16&17|64
Port IP-Address 16 70 64 1|16&17|64
Class of Service 4 71 64 1|16&17|64
FC-4 Types 32 72 64 1|16&17|64
FC-4 Descriptor 4-256 73 64 1|16&17|64
FC-4 Features 128 74 64 1|16&17|64
iFCP SCN bitmap 4 75 64 1|16&17|64
Port Role 4 76 64 1|16&17|64
Permanent Port Name 8 77 -- 1|16&17|64
FC-4 Type Code 4 95 -- 1|16&17|64
FC Node Name WWNN 8 96 64 1|16&17|64|96
Symbolic Node Name 4-256 97 96 64|96
Node IP-Address 16 98 96 64|96
Node IPA 8 99 96 64|96
Proxy iSCSI Name 4-256 101 96 64|96
Switch Name 8 128 128 128
Preferred ID 4 129 128 128
Assigned ID 4 130 128 128
Virtual_Fabric_ID 4-256 131 128 128
iSNS Server Vendor OUI 4 256 -- SOURCE Attribute
Vendor-Spec iSNS Srvr 257-384 -- SOURCE Attribute
Vendor-Spec Entity 385-512 1 1|2|16&17|32|64
Vendor-Spec Portal 513-640 16&17 1|16&17|32|64
Vendor-Spec iSCSI Node 641-768 32 16&17|32
Vendor-Spec FC Port Name 769-896 64 1|16&17|64
Vendor-Spec FC Node Name 897-1024 96 64|96
Vendor-Specific DDS 1025-1280 2049 2049
Vendor-Specific DD 1281-1536 2065 2065
Other Vendor-Specific 1537-2048
DD_Set ID 4 2049 2049 1|32|64|2049|2065
DD_Set Sym Name 4-256 2050 2049 2049
DD_Set Status 4 2051 2049 2049
DD_Set_Next_ID 4 2052 -- 2049
DD_ID 4 2065 2049 1|32|64|2049|2065
DD_Symbolic Name 4-256 2066 2065 2065
Tseng, et al. Standards Track [Page 74]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
DD_Member iSCSI Index 4 2067 2065 2065
DD_Member iSCSI Name 4-224 2068 2065 2065
DD_Member FC Port Name 8 2069 2065 2065
DD_Member Portal Index 4 2070 2065 2065
DD_Member Portal IP Addr 16 2071 2065 2065
DD_Member Portal TCP/UDP 4 2072 2065 2065
DD_Features 4 2078 2065 2065
DD_ID Next ID 4 2079 -- 2065
The following are descriptions of the columns used in the above
table:
Length: indicates the attribute length in bytes used for the TLV
format. Variable-length identifiers are NULL-terminated
and 4-byte aligned (NULLs are included in the length).
Tag: the IANA-assigned integer tag value used to identify the
attribute. All undefined tag values are reserved.
Reg Key: indicates the tag values for the object key in DevAttrReg
messages for registering a new attribute value in the
database. These tags represent attributes defined as
object keys in Section 4.
Query Key: indicates the possible tag values for the Message Key and
object key that are used in the DevAttrQry messages for
retrieving a stored value from the iSNS database.
The following is a summary of iSNS attribute tag values available for
future allocation by IANA at the time of publication:
Tag Values Reg Key Query Key
---------- ------- ---------
9-10, 13-15 1 1|2|16&17|32|64
21, 25-26, 30 16&17 1|16&17|32|64
39-41, 44-47 32 1|16&17|32
54-63 32|16&17 1|16&17|32|52
78-82, 85-94 64 1|16&17|64
102-127 96 64|96
132-255 -- SOURCE Attribute
2053-2064 2049 2049
2073-2077 2065 2065
2080-65535 To be assigned To be assigned
Registration and query keys for attributes with tags in the range
2080 to 65535 are to be documented in the RFC introducing the new
iSNS attributes. IANA will maintain registration of these values as
required by the new RFC.
Tseng, et al. Standards Track [Page 75]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
New iSNS attributes with any of the above tag values MAY also be
designated as "read-only" attributes. The new RFC introducing these
attributes as "read-only" SHALL document them as such, and IANA will
record their corresponding Registration Keys (Reg Keys) as "--".
6.2. Entity Identifier-Keyed Attributes
The following attributes are stored in the iSNS server using the
Entity Identifier attribute as the key.
6.2.1. Entity Identifier (EID)
The Entity Identifier (EID) is variable-length UTF-8 encoded NULL-
terminated text-based description for a Network Entity. This key
attribute uniquely identifies each Network Entity registered in the
iSNS server. The attribute length varies from 4 to 256 bytes
(including the NULL termination), and is a unique value within the
iSNS server.
If the iSNS client does not provide an EID during registration, the
iSNS server SHALL generate one that is unique within the iSNS
database. If an EID is to be generated, then the EID attribute value
in the registration message SHALL be empty (0 length). The generated
EID SHALL be returned in the registration response.
In environments where the iSNS server is integrated with a DNS
infrastructure, the Entity Identifier may be used to store the Fully
Qualified Domain Name (FQDN) of the iSCSI or iFCP device. FQDNs of
greater than 255 bytes MUST NOT be used.
If FQDNs are not used, the iSNS server can be used to generate EIDs.
EIDs generated by the iSNS server MUST begin with the string "isns:".
iSNS clients MUST NOT generate and register EIDs beginning with the
string "isns:".
This field MUST be normalized according to the nameprep template
[NAMEPREP] before it is stored in the iSNS database.
6.2.2. Entity Protocol
The Entity Protocol is a required 4-byte integer attribute that
indicates the block storage protocol used by the registered NETWORK
ENTITY. Values used for this attribute are assigned and maintained
by IANA. The initial set of protocols supported by iSNS is as
follows:
Tseng, et al. Standards Track [Page 76]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Value Entity Protocol Type
----- --------------------
1 No Protocol
2 iSCSI
3 iFCP
All others To be assigned by IANA
'No Protocol' is used to indicate that the Network Entity does not
support an IP block storage protocol. A Control Node or monitoring
Node would likely (but not necessarily) use this value.
This attribute is required during initial registration of the Network
Entity.
6.2.3. Management IP Address
This field contains the IP Address that may be used to manage the
Network Entity and all Storage Nodes contained therein via the iSNS
MIB [iSNSMIB]. Some implementations may also use this IP address to
support vendor-specific proprietary management protocols. The
Management IP Address is a 16-byte field that may contain an IPv4 or
IPv6 address. When this field contains an IPv4 value, it is stored
as an IPv4-mapped IPv6 address. That is, the most significant 10
bytes are set to 0x00, with the next two bytes set to 0xFFFF
[RFC2373]. When this field contains an IPv6 value, the entire 16-
byte field is used. If this field is not set, then in-band
management through the IP address of one of the Portals of the
Network Entity is assumed.
6.2.4. Entity Registration Timestamp
This field indicates the most recent time when the Network Entity
registration occurred or when an associated object attribute was
updated or queried by the iSNS client registering the Network Entity.
The time format is, in seconds, the update period since the standard
base time of 00:00:00 GMT on January 1, 1970. This field cannot be
explicitly registered. This timestamp TLV format is also used in the
SCN and ESI messages.
6.2.5. Protocol Version Range
This field contains the minimum and maximum version of the block
storage protocol supported by the Network Entity. The most
significant two bytes contain the maximum version supported, and the
least significant two bytes contain the minimum version supported.
If a range is not registered, then the Network Entity is assumed to
Tseng, et al. Standards Track [Page 77]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
support all versions of the protocol. The value 0xffff is a wildcard
that indicates no minimum or maximum. If the Network Entity does not
support a protocol, then this field SHALL be set to 0.
6.2.6. Registration Period
This 4-byte unsigned integer field indicates the maximum period, in
seconds, that the registration SHALL be maintained by the server
without receipt of an iSNS message from the iSNS client that
registered the Network Entity. Entities that are not registered for
ESI monitoring MUST have a non-zero Registration Period. If a
Registration Period is not requested by the iSNS client and Entity
Status Inquiry (ESI) messages are not enabled for that client, then
the Registration Period SHALL be set to a non-zero value by the iSNS
server. This implementation-specific value for the Registration
Period SHALL be returned in the registration response to the iSNS
client. The Registration Period may be set to zero, indicating its
non-use, only if ESI messages are enabled for that Network Entity.
The registration SHALL be removed from the iSNS database if an iSNS
Protocol message is not received from the iSNS client before the
registration period has expired. Receipt of any iSNS Protocol
message from the iSNS client automatically refreshes the Entity
Registration Period and Entity Registration Timestamp. To prevent a
registration from expiring, the iSNS client should send an iSNS
Protocol message to the iSNS server at intervals shorter than the
registration period. Such a message can be as simple as a query for
one of its own attributes, using its associated iSCSI Name or FC Port
Name WWPN as the Source attribute.
For an iSNS client that is supporting a Network Entity with multiple
Storage Node objects, receipt of an iSNS message from any Storage
Node of that Network Entity is sufficient to refresh the registration
for all Storage Node objects of the Network Entity.
If ESI support is requested as part of a Portal registration, the ESI
Response message received from the iSNS client by the iSNS server
SHALL refresh the registration.
6.2.7. Entity Index
The Entity Index is an unsigned non-zero integer value that uniquely
identifies each Network Entity registered in the iSNS server. Upon
initial registration of a Network Entity, the iSNS server assigns an
unused value for the Entity Index. Each Network Entity in the iSNS
database MUST be assigned a value for the Entity Index that is not
Tseng, et al. Standards Track [Page 78]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
assigned to any other Network Entity. Furthermore, Entity Index
values for recently deregistered Network Entities SHOULD NOT be
reused in the short term.
The Entity Index MAY be used to represent the Network Entity in
situations when the Entity Identifier is too long or otherwise
inappropriate. An example of this is when SNMP is used for
management, as described in Section 2.10.
6.2.8. Entity Next Index
This is a virtual attribute containing a 4-byte integer value that
indicates the next available (i.e., unused) Entity Index value. This
attribute may only be queried; the iSNS server SHALL return an error
code of 3 (Invalid Registration) to any client that attempts to
register a value for this attribute. A Message Key is not required
when exclusively querying for this attribute.
The Entity Next Index MAY be used by an SNMP client to create an
entry in the iSNS server. SNMP requirements are described in Section
2.10.
6.2.9. Entity ISAKMP Phase-1 Proposals
This field contains the IKE Phase-1 proposal, listing in decreasing
order of preference the protection suites acceptable to protect all
IKE Phase-2 messages sent and received by the Network Entity. This
includes Phase-2 SAs from the iSNS client to the iSNS server as well
as to peer iFCP and/or iSCSI devices. This attribute contains the SA
payload, proposal payload(s), and transform payload(s) in the ISAKMP
format defined in [RFC2408].
This field should be used if the implementer wishes to define a
single phase-1 SA security configuration used to protect all phase-2
IKE traffic. If the implementer desires to have a different phase-1
SA security configuration to protect each Portal interface, then the
Portal Phase-1 Proposal (Section 6.3.10) should be used.
6.2.10. Entity Certificate
This attribute contains one or more X.509 certificates that are bound
to the Network Entity. This certificate is uploaded and registered
to the iSNS server by clients wishing to allow other clients to
authenticate themselves and to access the services offered by that
Network Entity. The format of the X.509 certificate is found in
[RFC3280]. This certificate MUST contain a Subject Name with an
empty sequence and MUST contain a SubjectAltName extension encoded
Tseng, et al. Standards Track [Page 79]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
with the dNSName type. The Entity Identifier (Section 6.2.1) of the
identified Entity MUST be stored in the SubjectAltName field of the
certificate.
6.3. Portal-Keyed Attributes
The following Portal attributes are registered in the iSNS database
using the combined Portal IP-Address and Portal TCP/UDP Port as the
key. Each Portal is associated with one Entity Identifier object
key.
6.3.1. Portal IP Address
This attribute is the IP address of the Portal through which a
Storage Node can transmit and receive storage data. The Portal IP
Address is a 16-byte field that may contain an IPv4 or IPv6 address.
When this field contains an IPv4 address, it is stored as an IPv4-
mapped IPv6 address. That is, the most significant 10 bytes are set
to 0x00, with the next 2 bytes set to 0xFFFF [RFC2373]. When this
field contains an IPv6 address, the entire 16-byte field is used.
The Portal IP Address and the Portal TCP/UDP Port number (see 6.3.2
below) are used as a key to identify a Portal uniquely. It is a
required attribute for registration of a Portal.
6.3.2. Portal TCP/UDP Port
The TCP/UDP port of the Portal through which a Storage Node can
transmit and receive storage data. Bits 16 to 31 represents the
TCP/UDP port number. Bit 15 represents the port type. If bit 15 is
set, then the port type is UDP. Otherwise it is TCP. Bits 0 to 14
are reserved.
If the field value is 0, then the port number is the implied
canonical port number and type of the protocol indicated by the
associated Entity Type.
The Portal IP Address and the Portal TCP/UDP Port number are used as
a key to identify a Portal uniquely. It is a required attribute for
registration of a Portal.
6.3.3. Portal Symbolic Name
A variable-length UTF-8 encoded NULL-terminated text-based
description of up to 256 bytes. The Portal Symbolic Name is a user-
readable description of the Portal entry in the iSNS server.
Tseng, et al. Standards Track [Page 80]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.3.4. Entity Status Inquiry Interval
This field indicates the requested time, in seconds, between Entity
Status Inquiry (ESI) messages sent from the iSNS server to this
Network Entity. ESI messages can be used to verify that a Portal
registration continues to be valid. To request monitoring by the
iSNS server, an iSNS client registers a non-zero value for this
Portal attribute using a DevAttrReg message. The client MUST
register an ESI Port on at least one of its Portals to receive the
ESI monitoring.
If the iSNS server does not receive an expected response to an ESI
message, it SHALL attempt an administratively configured number of
re-transmissions of the ESI message. The ESI Interval period begins
with the iSNS server's receipt of the last ESI Response. All re-
transmissions MUST be sent before twice the ESI Interval period has
passed. If no response is received from any of the ESI messages,
then the Portal SHALL be deregistered. Note that only Portals that
have registered a value in their ESI Port field can be deregistered
in this way.
If all Portals associated with a Network Entity that have registered
for ESI messages are deregistered due to non-response, and if no
registrations have been received from the client for at least two ESI
Interval periods, then the Network Entity and all associated objects
(including Storage Nodes) SHALL be deregistered.
If the iSNS server is unable to support ESI messages or the ESI
Interval requested, it SHALL either reject the ESI request by
returning an "ESI Not Available" Status Code or modify the ESI
Interval attribute by selecting its own suitable value and returning
that value in the Operating Attributes of the registration response
message.
If at any time an iSNS client that is registered for ESI messages has
not received an ESI message to any of its Portals as expected, then
the client MAY attempt to query the iSNS server using a DevAttrQry
message using its Entity_ID as the key. If the query result is the
error "no such entry", then the client SHALL close all remaining TCP
connections to the iSNS server and assume that it is no longer
registered in the iSNS database. Such a client MAY attempt re-
registration.
Tseng, et al. Standards Track [Page 81]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.3.5. ESI Port
This field contains the TCP or UDP port used for ESI monitoring by
the iSNS server at the Portal IP Address. Bits 16 to 31 represent
the port number. If bit 15 is set, then the port type is UDP.
Otherwise, the port is TCP. Bits 0 to 14 are reserved.
If the iSNS client registers a valid TCP or UDP port number in this
field, then the client SHALL allow ESI messages to be received at the
indicated TCP or UDP port. If a TCP port is registered and a pre-
existing TCP connection from that TCP port to the iSNS server does
not already exist, then the iSNS client SHALL accept new TCP
connections from the iSNS server at the indicated TCP port.
The iSNS server SHALL return an error if a Network Entity is
registered for ESI monitoring and none of the Portals of that Network
Entity has an entry for the ESI Port field. If multiple Portals have
a registered ESI port, then the ESI message may be delivered to any
one of the indicated Portals.
6.3.6. Portal Index
The Portal Index is a 4-byte non-zero integer value that uniquely
identifies each Portal registered in the iSNS database. Upon initial
registration of a Portal, the iSNS server assigns an unused value for
the Portal Index of that Portal. Each Portal in the iSNS database
MUST be assigned a value for the Portal Index that is not assigned to
any other Portal. Furthermore, Portal Index values for recently
deregistered Portals SHOULD NOT be reused in the short term.
The Portal Index MAY be used to represent a registered Portal in
situations where the Portal IP-Address and Portal TCP/UDP Port is
unwieldy to use. An example of this is when SNMP is used for
management, as described in Section 2.10.
6.3.7. SCN Port
This field contains the TCP or UDP port used by the iSNS client to
receive SCN messages from the iSNS server. When a value is
registered for this attribute, an SCN message may be received on the
indicated port for any of the Storage Nodes supported by the Portal.
Bits 16 to 31 contain the port number. If bit 15 is set, then the
port type is UDP. Otherwise, the port type is TCP. Bits 0 to 14 are
reserved.
If the iSNS client registers a valid TCP or UDP port number in this
field, then the client SHALL allow SCN messages to be received at the
indicated TCP or UDP port. If a TCP port is registered and a pre-
Tseng, et al. Standards Track [Page 82]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
existing TCP connection from that TCP port to the iSNS server does
not already exist, then the iSNS client SHALL accept new TCP
connections from the iSNS server at the indicated TCP port.
The iSNS server SHALL return an error if an SCN registration message
is received and none of the Portals of the Network Entity has an
entry for the SCN Port. If multiple Portals have a registered SCN
Port, then the SCN SHALL be delivered to any one of the indicated
Portals of that Network Entity.
6.3.8. Portal Next Index
This is a virtual attribute containing a 4-byte integer value that
indicates the next available (i.e., unused) Portal Index value. This
attribute may only be queried; the iSNS server SHALL return an error
code of 3 (Invalid Registration) to any client that attempts to
register a value for this attribute. A Message Key is not required
when exclusively querying for this attribute.
The Portal Next Index MAY be used by an SNMP client to create an
entry in the iSNS server. SNMP requirements are described in Section
2.10.
6.3.9. Portal Security Bitmap
This 4-byte field contains flags that indicate security attribute
settings for the Portal. Bit 31 (Lsb) of this field must be 1
(enabled) for this field to contain significant information. If Bit
31 is enabled, this signifies that the iSNS server can be used to
store and distribute security policies and settings for iSNS clients
(i.e., iSCSI devices). Bit 30 must be 1 for bits 25-29 to contain
significant information. All other bits are reserved for non-
IKE/IPSec security mechanisms to be specified in the future.
Bit Position Flag Description
------------ ----------------
25 1 = Tunnel Mode Preferred; 0 = No Preference
26 1 = Transport Mode Preferred; 0 = No Preference
27 1 = Perfect Forward Secrecy (PFS) Enabled;
0 = PFS Disabled
28 1 = Aggressive Mode Enabled; 0 = Disabled
29 1 = Main Mode Enabled; 0 = MM Disabled
30 1 = IKE/IPSec Enabled; 0 = IKE/IPSec Disabled
31 (Lsb) 1 = Bitmap VALID; 0 = INVALID
All others RESERVED
Tseng, et al. Standards Track [Page 83]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.3.10. Portal ISAKMP Phase-1 Proposals
This field contains the IKE Phase-1 proposal listing in decreasing
order of preference of the protection suites acceptable to protect
all IKE Phase-2 messages sent and received by the Portal. This
includes Phase-2 SAs from the iSNS client to the iSNS server as well
as to peer iFCP and/or iSCSI devices. This attribute contains the SA
payload, proposal payload(s), and transform payload(s) in the ISAKMP
format defined in [RFC2408].
This field should be used if the implementer wishes to define phase-1
SA security configuration on a per-Portal basis, as opposed to on a
per-Network Entity basis. If the implementer desires to have a
single phase-1 SA security configuration to protect all phase-2
traffic regardless of the interface used, then the Entity Phase-1
Proposal (Section 6.2.9) should be used.
6.3.11. Portal ISAKMP Phase-2 Proposals
This field contains the IKE Phase-2 proposal, in ISAKMP format
[RFC2408], listing in decreasing order of preference the security
proposals acceptable to protect traffic sent and received by the
Portal. This field is used only if bits 31, 30, and 29 of the
Security Bitmap (see 6.3.9) are enabled. This attribute contains the
SA payload, proposal payload(s), and associated transform payload(s)
in the ISAKMP format defined in [RFC2408].
6.3.12. Portal Certificate
This attribute contains one or more X.509 certificates that are a
credential of the Portal. This certificate is used to identify and
authenticate communications to the IP address and TCP/UDP Port
supported by the Portal. The format of the X.509 certificate is
specified in [RFC3280]. This certificate MUST contain a Subject Name
with an empty sequence and MUST contain a SubjectAltName extension
encoded with the iPAddress type. The Portal IP Address (Section
6.3.1) of the identified Portal SHALL be stored in the SubjectAltName
field of the certificate.
6.4. iSCSI Node-Keyed Attributes
The following attributes are stored in the iSNS database using the
iSCSI Name attribute as the key. Each set of Node-Keyed attributes
is associated with one Entity Identifier object key.
Although the iSCSI Name key is associated with one Entity Identifier,
it is unique across the entire iSNS database.
Tseng, et al. Standards Track [Page 84]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.4.1. iSCSI Name
This is a variable-length UTF-8 encoded NULL-terminated text-based
description of up to 224 bytes. This key attribute is required for
iSCSI Storage Nodes and is provided by the iSNS client. The
registered iSCSI Name MUST conform to the format described in [iSCSI]
for iSCSI Names. The maximum size for an iSCSI Name is 223 bytes.
Including the NULL character and 4-byte alignment (see Section
5.3.1), the maximum iSCSI Name field size is 224 bytes.
If an iSCSI Name is registered without an EID key, then a Network
Entity SHALL be created and an EID assigned. The assigned EID SHALL
be returned in the registration response as an operating attribute.
This field MUST be normalized according to the stringprep template
[STRINGPREP] before it is stored in the iSNS database.
6.4.2. iSCSI Node Type
This required 32-bit field is a bitmap indicating the type of iSCSI
Storage Node. The bit positions are defined below. A set bit (1)
indicates that the Node has the corresponding characteristics.
Bit Position Node Type
------------ ---------
29 Control
30 Initiator
31 (Lsb) Target
All others RESERVED
If the Target bit is set to 1, then the Node represents an iSCSI
target. The Target bit MAY be set by iSNS clients using the iSNSP.
If the Initiator bit is set to 1, then the Node represents an iSCSI
initiator. The Initiator bit MAY be set by iSNS clients using the
iSNSP.
If the control bit is set to 1, then the Node represents a gateway, a
management station, a backup iSNS server, or another device that is
not an initiator or target, but that requires the ability to send and
receive iSNSP messages, including state change notifications.
Setting the control bit is an administrative task that MUST be
performed on the iSNS server; iSNS clients SHALL NOT be allowed to
change this bit using the iSNSP.
Tseng, et al. Standards Track [Page 85]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
This field MAY be used by the iSNS server to distinguish among
permissions by different iSCSI Node types for accessing various iSNS
functions. More than one Node Type bit may be simultaneously
enabled.
6.4.3. iSCSI Node Alias
This is a variable-length UTF-8 encoded NULL-terminated text-based
description of up to 256 bytes. The Alias is a user-readable
description of the Node entry in the iSNS database.
6.4.4. iSCSI Node SCN Bitmap
The iSCSI Node SCN Bitmap indicates events for which the registering
iSNS client wishes to receive a notification message. The following
table displays events that result in notifications, and the bit field
in the SCN Bitmap that, when enabled, results in the corresponding
notification.
Note that this field is of dual use: it is used in the SCN
registration process to define interested events that will trigger an
SCN message, and it is also contained in each SCN message itself, to
indicate the type of event that triggered the SCN message. A set bit
(1) indicates the corresponding type of SCN.
Bit Position Flag Description
------------ ----------------
24 INITIATOR AND SELF INFORMATION ONLY
25 TARGET AND SELF INFORMATION ONLY
26 MANAGEMENT REGISTRATION/SCN
27 OBJECT REMOVED
28 OBJECT ADDED
29 OBJECT UPDATED
30 DD/DDS MEMBER REMOVED (Mgmt Reg/SCN only)
31 (Lsb) DD/DDS MEMBER ADDED (Mgmt Reg/SCN only)
All others RESERVED
DD/DDS MEMBER REMOVED indicates that an existing member of a
Discovery Domain and/or Discovery Domain Set has been removed.
DD/DDS MEMBER ADDED indicates that a new member was added to an
existing DD and/or DDS.
OBJECT REMOVED, OBJECT ADDED, and OBJECT UPDATED indicate a Network
Entity, Portal, Storage Node, FC Device, DD, and/or DDS object was
removed from, added to, or updated in the Discovery Domain or in the
iSNS database (Control Nodes only).
Tseng, et al. Standards Track [Page 86]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Regular SCNs provide information about objects that are updated in,
added to or removed from Discovery Domains of which the Storage Node
is a member. An SCN or SCN registration is considered a regular SCN
or regular SCN registration if the MANAGEMENT REGISTRATION/SCN flag
is cleared. All iSNS clients may register for regular SCNs.
Management SCNs provide information about all changes to the network,
regardless of discovery domain membership. Registration for
management SCNs is indicated by setting bit 26 to 1. Only Control
Nodes may register for management SCNs. Bits 30 and 31 may only be
enabled if bit 26 is set to 1.
TARGET AND SELF INFORMATION ONLY SCNs (bit 25) provides information
only about changes to target devices, or if the iSCSI Storage Node
itself has undergone a change. Similarly, INITIATOR AND SELF
INFORMATION ONLY SCNs (bit 24) provides information only about
changes to initiator Nodes, or to the target itself.
6.4.5. iSCSI Node Index
The iSCSI Node Index is a 4-byte non-zero integer value used as a key
that uniquely identifies each iSCSI Storage Node registered in the
iSNS database. Upon initial registration of the iSCSI Storage Node,
the iSNS server assigns an unused value for the iSCSI Node Index.
Each iSCSI Node MUST be assigned a value for the iSCSI Node Index
that is not assigned to any other iSCSI Storage Node. Furthermore,
iSCSI Node Index values for recently deregistered iSCSI Storage Nodes
SHOULD NOT be reused in the short term.
The iSCSI Node Index may be used as a key to represent a registered
Node in situations where the iSCSI Name is too long to be used as a
key. An example of this is when SNMP is used for management, as
described in Section 2.10.
The value assigned for the iSCSI Node Index SHALL persist as long as
the iSCSI Storage Node is registered in the iSNS database or a member
of a Discovery Domain. An iSCSI Node Index value that is assigned
for a Storage Node SHALL NOT be used for any other Storage Node as
long as the original node is registered in the iSNS database or a
member of a Discovery Domain.
6.4.6. WWNN Token
This field contains a globally unique 64-bit integer value that can
be used to represent the World Wide Node Name of the iSCSI device in
a Fibre Channel fabric. This identifier is used during the device
registration process and MUST conform to the requirements in [FC-FS].
Tseng, et al. Standards Track [Page 87]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
The FC-iSCSI gateway uses the value found in this field to register
the iSCSI device in the Fibre Channel name server. It is stored in
the iSNS server to prevent conflict when "proxy" WWNN values are
assigned to iSCSI initiators establishing storage sessions to devices
in the FC fabric.
If the iSNS client does not assign a value for WWNN Token, then the
iSNS server SHALL provide a value for this field upon initial
registration of the iSCSI Storage Node. The process by which the
WWNN Token is assigned by the iSNS server MUST conform to the
following requirements:
1. The assigned WWNN Token value MUST be unique among all WWN
entries in the existing iSNS database, and among all devices that
can potentially be registered in the iSNS database.
2. Once the value is assigned, the iSNS server MUST persistently
save the mapping between the WWNN Token value and registered
iSCSI Name. That is, successive re-registrations of the iSCSI
Storage Node keyed by the same iSCSI Name maintain the original
mapping to the associated WWNN Token value in the iSNS server.
Similarly, the mapping SHALL be persistent across iSNS server
reboots. Once assigned, the mapping can only be changed if a
DevAttrReg message from an authorized iSNS client explicitly
provides a different WWNN Token value.
3. Once a WWNN Token value has been assigned and mapped to an iSCSI
name, that WWNN Token value SHALL NOT be reused or mapped to any
other iSCSI name.
4. The assigned WWNN Token value MUST conform to the formatting
requirements of [FC-FS] for World Wide Names (WWNs).
An iSNS client, such as an FC-iSCSI gateway or the iSCSI initiator,
MAY register its own WWNN Token value or overwrite the iSNS Server-
supplied WWNN Token value, if it wishes to supply its own iSCSI-FC
name mapping. This is accomplished using the DevAttrReg message with
the WWNN Token (tag=37) as an operating attribute. Once overwritten,
the new WWNN Token value MUST be stored and saved by the iSNS server,
and all requirements specified above continue to apply. If an iSNS
client attempts to register a value for this field that is not unique
in the iSNS database or that is otherwise invalid, then the
registration SHALL be rejected with an Status Code of 3 (Invalid
Registration).
Tseng, et al. Standards Track [Page 88]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
There MAY be matching records in the iSNS database for the Fibre
Channel device specified by the WWNN Token. These records may
contain device attributes for that FC device registered in the Fibre
Channel fabric name server.
6.4.7. iSCSI Node Next Index
This is a virtual attribute containing a 4-byte integer value that
indicates the next available (i.e., unused) iSCSI Node Index value.
This attribute may only be queried; the iSNS server SHALL return an
error code of 3 (Invalid Registration) to any client that attempts to
register a value for this attribute. A Message Key is not required
when exclusively querying for this attribute.
The iSCSI Node Next Index MAY be used by an SNMP client to create an
entry in the iSNS server. SNMP requirements are described in Section
2.10.
6.4.8. iSCSI AuthMethod
This attribute contains a NULL-terminated string of UTF-8 text
listing the iSCSI authentication methods enabled for this iSCSI
Storage Node, in order of preference. The text values used to
identify iSCSI authentication methods are embedded in this string
attribute and delineated by a comma. The text values are identical
to those found in the main iSCSI document [iSCSI]; additional
vendor-specific text values are also possible.
Text Value Description Reference
---------- ----------- ---------
KB5 Kerberos V5 [RFC1510]
SPKM1 Simple Public Key GSS-API [RFC2025]
SPKM2 Simple Public Key GSS-API [RFC2025]
SRP Secure Remote Password [RFC2945]
CHAP Challenge Handshake Protocol [RFC1994]
none No iSCSI Authentication
6.5. Portal Group (PG) Object-Keyed Attributes
The following attributes are used to associate Portal and iSCSI
Storage Node objects. PG objects are stored in the iSNS database
using the PG iSCSI Name, the PG Portal IP Address, and the PG Portal
TCP/UDP Port as keys. New PG objects are implicitly or explicitly
created at the time that the corresponding Portal and/or iSCSI
Storage Node objects are registered. Section 3.4 has a general
discussion of PG usage. For further details on use of Portal Groups,
see [iSCSI].
Tseng, et al. Standards Track [Page 89]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.5.1. Portal Group iSCSI Name
This is the iSCSI Name for the iSCSI Storage Node that is associated
with the PG object. This name MAY represent an iSCSI Storage Node
not currently registered in the server.
6.5.2. PG Portal IP Addr
This is the Portal IP Address attribute for the Portal that is
associated with the PG object. This Portal IP Address MAY be that of
a Portal that is not currently registered in the server.
6.5.3. PG Portal TCP/UDP Port
This is the Portal TCP/UDP Port attribute for the Portal that is
associated with the PG object. This Portal TCP/UDP Port MAY be that
of a Portal that is not currently registered in the server.
6.5.4. Portal Group Tag (PGT)
This field is used to group Portals in order to coordinate
connections in a session across Portals to a specified iSCSI Node.
The PGT is a value in the range of 0-65535, or NULL. A NULL PGT
value is registered by using 0 for the length in the TLV during
registration. The two least significant bytes of the value contain
the PGT for the object. The two most significant bytes are reserved.
If a PGT value is not explicitly registered for an iSCSI Storage Node
and Portal pair, then the PGT value SHALL be implicitly registered as
0x00000001.
6.5.5. Portal Group Index
The PG Index is a 4-byte non-zero integer value used as a key that
uniquely identifies each PG object registered in the iSNS database.
Upon initial registration of a PG object, the iSNS server MUST assign
an unused value for the PG Index. Furthermore, PG Index values for
recently deregistered PG objects SHOULD NOT be reused in the short
term.
The PG Index MAY be used as the key to reference a registered PG in
situations where a unique index for each PG object is required. It
MAY also be used as the message key in an iSNS message to query or
update a pre-existing PG object. An example of this is when SNMP is
used for management, as described in Section 2.10. The value
assigned for the PG Index SHALL persist as long as the server is
active.
Tseng, et al. Standards Track [Page 90]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.5.6. Portal Group Next Index
The PG Next Index is a virtual attribute containing a 4-byte integer
value that indicates the next available (i.e., unused) PG Index
value. This attribute may only be queried; the iSNS server SHALL
return an error code of 3 (Invalid Registration) to any client that
attempts to register a value for this attribute. A Message Key is
not required when exclusively querying for this attribute.
The Portal Group Next Index MAY be used by an SNMP client to create
an entry in the iSNS server. SNMP requirements are described in
Section 2.10.
6.6. FC Port Name-Keyed Attributes
The following attributes are registered in the iSNS database using
the FC Port World Wide Name (WWPN) attribute as the key. Each set of
FC Port-Keyed attributes is associated with one Entity Identifier
object key.
Although the FC Port World Wide Name is associated with one Entity
Identifier, it is also globally unique.
6.6.1. FC Port Name (WWPN)
This 64-bit identifier uniquely defines the FC Port, and it is the
World Wide Port Name (WWPN) of the corresponding Fibre Channel
device. This attribute is the key for the iFCP Storage Node. This
globally unique identifier is used during the device registration
process, and it uses a value conforming to IEEE EUI-64 [EUI-64].
6.6.2. Port ID (FC_ID)
The Port Identifier is a Fibre Channel address identifier assigned to
an N_Port or NL_Port during fabric login. The format of the Port
Identifier is defined in [FC-FS]. The least significant 3 bytes
contain this address identifier. The most significant byte is
RESERVED.
Tseng, et al. Standards Track [Page 91]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.6.3. FC Port Type
Indicates the type of FC port. Encoded values for this field are
listed in the following table:
Type Description
---- -----------
0x0000 Unidentified/Null Entry
0x0001 Fibre Channel N_Port
0x0002 Fibre Channel NL_Port
0x0003 Fibre Channel F/NL_Port
0x0004-0080 RESERVED
0x0081 Fibre Channel F_Port
0x0082 Fibre Channel FL_Port
0x0083 RESERVED
0x0084 Fibre Channel E_Port
0x0085-00FF RESERVED
0xFF11 RESERVED
0xFF12 iFCP Port
0xFF13-FFFF RESERVED
6.6.4. Symbolic Port Name
This is a variable-length UTF-8 encoded NULL-terminated text-based
description of up to 256 bytes that is associated with the iSNS-
registered FC Port Name in the network.
6.6.5. Fabric Port Name (FWWN)
This 64-bit identifier uniquely defines the fabric port. If the port
of the FC Device is attached to a Fibre Channel fabric port with a
registered Port Name, then that fabric Port Name SHALL be indicated
in this field.
6.6.6. Hard Address
This field is the requested hard address 24-bit NL Port Identifier,
included in the iSNSP for compatibility with Fibre Channel Arbitrated
Loop devices and topologies. The least significant 3 bytes of this
field contain the address. The most significant byte is RESERVED.
6.6.7. Port IP Address
The Fibre Channel IP address associated with the FC Port. When this
field contains an IPv4 value, it is stored as an IPv4-mapped IPv6
address. That is, the most significant 10 bytes are set to 0x00,
with the next two bytes set to 0xFFFF [RFC2373]. When an IPv6 value
is contained in this field, then the entire 16-byte field is used.
Tseng, et al. Standards Track [Page 92]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.6.8. Class of Service (COS)
This 32-bit bit-map field indicates the Fibre Channel Class of
Service types that are supported by the registered port. In the
following table, a set bit (1) indicates a Class of Service
supported.
Bit Position Description
------------ -----------
29 Fibre Channel Class 2 Supported
28 Fibre Channel Class 3 Supported
6.6.9. FC-4 Types
This 32-byte field indicates the FC-4 protocol types supported by the
associated port. This field can be used to support Fibre Channel
devices and is consistent with FC-GS-4.
6.6.10. FC-4 Descriptor
This is a variable-length UTF-8 encoded NULL-terminated text-based
description of up to 256 bytes that is associated with the iSNS-
registered device port in the network. This field can be used to
support Fibre Channel devices and is consistent with FC-GS-4.
6.6.11. FC-4 Features
This is a 128-byte array, 4 bits per type, for the FC-4 protocol
types supported by the associated port. This field can be used to
support Fibre Channel devices and is consistent with FC-GS-4.
6.6.12. iFCP SCN Bitmap
This field indicates the events the iSNS client is interested in.
These events can cause SCNs to be generated. SCNs provide
information about objects that are updated in, added to or removed
from Discovery Domains of which the source and destination are a
member. Management SCNs provide information about all changes to the
network. A set bit (1) indicates the type of SCN for the bitmap as
follows:
Tseng, et al. Standards Track [Page 93]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Bit Position Flag Description
------------ ----------------
24 INITIATOR AND SELF INFORMATION ONLY
25 TARGET AND SELF INFORMATION ONLY
26 MANAGEMENT REGISTRATION/SCN
27 OBJECT REMOVED
28 OBJECT ADDED
29 OBJECT UPDATED
30 DD/DDS MEMBER REMOVED (Mgmt Reg/SCN only)
31 (Lsb) DD/DDS MEMBER ADDED (Mgmt Reg/SCN only)
All others RESERVED
Further information on the use of the bit positions specified above
can be found in Section 6.4.4.
6.6.13. Port Role
This required 32-bit field is a bitmap indicating the type of iFCP
Storage Node. The bit fields are defined below. A set bit indicates
the Node has the corresponding characteristics.
Bit Position Node Type
------------ ---------
29 Control
30 FCP Initiator
31 (Lsb) FCP Target
All Others RESERVED
If the 'Target' bit is set to 1, then the port represents an FC
target. Setting of the 'Target' bit MAY be performed by iSNS clients
using the iSNSP.
If the 'Initiator' bit is set to 1, then the port represents an FC
initiator. Setting of the 'Initiator' bit MAY be performed by iSNS
clients using the iSNSP.
If the 'Control' bit is set to 1, then the port represents a gateway,
a management station, an iSNS backup server, or another device.
This is usually a special device that is neither an initiator nor a
target, which requires the ability to send and receive iSNSP
messages, including state-change notifications. Setting the control
bit is an administrative task that MUST be administratively
configured on the iSNS server; iSNS clients SHALL NOT be allowed to
change this bit using the iSNSP.
Tseng, et al. Standards Track [Page 94]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
This field MAY be used by the iSNS server to distinguish among
permissions by different iSNS clients. For example, an iSNS server
implementation may be administratively configured to allow only
targets to receive ESIs, or to permit only Control Nodes to add,
modify, or delete discovery domains.
6.6.14. Permanent Port Name (PPN)
The Permanent Port Name can be used to support Fibre Channel devices
and is consistent with the PPN description in FC-GS-4 [FC-GS-4]. The
format of the PPN is identical to the FC Port Name WWPN attribute
format.
6.7. Node-Keyed Attributes
The following attributes are registered in the iSNS database using
the FC Node Name (WWNN) attribute as the key. Each set of FC Node-
Keyed attributes represents a single device and can be associated
with many FC Ports.
The FC Node Name is unique across the entire iSNS database.
6.7.1. FC Node Name (WWNN)
The FC Node Name is a 64-bit identifier that is the World Wide Node
Name (WWNN) of the corresponding Fibre Channel device. This
attribute is the key for the FC Device. This globally unique
identifier is used during the device registration process, and it
uses a value conforming to IEEE EUI-64 [EUI-64].
6.7.2. Symbolic Node Name
This is a variable-length UTF-8 encoded NULL-terminated text-based
description of up to 256 bytes that is associated with the iSNS-
registered FC Device in the network.
6.7.3. Node IP Address
This IP address is associated with the device Node in the network.
This field is included for compatibility with Fibre Channel. When
this field contains an IPv4 value, it is stored as an IPv4-mapped
IPv6 address. That is, the most significant 10 bytes are set to
0x00, with the next two bytes set to 0xFFFF [RFC2373]. When an IPv6
value is contained in this field, the entire 16-byte field is used.
Tseng, et al. Standards Track [Page 95]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.7.4. Node IPA
This field is the 8-byte Fibre Channel Initial Process Associator
(IPA) associated with the device Node in the network. The initial
process associator is used for communication between Fibre Channel
devices.
6.7.5. Proxy iSCSI Name
This is a variable-length UTF-8 encoded NULL-terminated text-based
field that contains the iSCSI Name used to represent the FC Node in
the IP network. It is used as a pointer to the matching iSCSI Name
entry in the iSNS server. Its value is usually registered by an FC-
iSCSI gateway connecting the IP network to the fabric containing the
FC device.
Note that if this field is used, there SHOULD be a matching entry in
the iSNS database for the iSCSI device specified by the iSCSI name.
The database entry should include the full range of iSCSI attributes
needed for discovery and management of the "iSCSI proxy image" of the
FC device.
6.8. Other Attributes
The following are not attributes of the previously-defined objects.
6.8.1. FC-4 Type Code
This is a 4-byte field used to provide a FC-4 type during a FC-4 Type
query. The FC-4 types are consistent with the FC-4 Types as defined
in FC-FS. Byte 0 contains the FC-4 type. All other bytes are
reserved.
6.8.2. iFCP Switch Name
The iFCP Switch Name is a 64-bit World Wide Name (WWN) identifier
that uniquely identifies a distinct iFCP gateway in the network.
This globally unique identifier is used during the switch
registration/FC_DOMAIN_ID assignment process. The iFCP Switch Name
value used MUST conform to the requirements stated in [FC-FS] for
World Wide Names. The iSNS server SHALL track the state of all
FC_DOMAIN_ID values that have been allocated to each iFCP Switch
Name. If a given iFCP Switch Name is deregistered from the iSNS
database, then all FC_DOMAIN_ID values allocated to that iFCP Switch
Name SHALL be returned to the unused pool of values.
Tseng, et al. Standards Track [Page 96]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.8.3. iFCP Transparent Mode Commands
6.8.3.1. Preferred ID
This is a 4-byte unsigned integer field, and it is the requested
value that the iSNS client wishes to use for the FC_DOMAIN_ID. The
iSNS server SHALL grant the iSNS client the use of the requested
value as the FC_DOMAIN_ID, if the requested value has not already
been allocated. If the requested value is not available, the iSNS
server SHALL return a different value that has not been allocated.
6.8.3.2. Assigned ID
This is a 4-byte unsigned integer field that is used by an iFCP
gateway to reserve its own unique FC_DOMAIN_ID value from the range 1
to 239. When a FC_DOMAIN_ID is no longer required, it SHALL be
released by the iFCP gateway using the RlseDomId message. The iSNS
server MUST use the Entity Status Inquiry message to determine
whether an iFCP gateway is still present on the network.
6.8.3.3. Virtual_Fabric_ID
This is a variable-length UTF-8 encoded NULL-terminated text-based
field of up to 256 bytes. The Virtual_Fabric_ID string is used as a
key attribute to identify a range of non-overlapping FC_DOMAIN_ID
values to be allocated using RqstDomId. Each Virtual_Fabric_ID
string submitted by an iSNS client SHALL have its own range of non-
overlapping FC_DOMAIN_ID values to be allocated to iSNS clients.
6.9. iSNS Server-Specific Attributes
Access to the following attributes may be administratively
controlled. These attributes are specific to the iSNS server
instance; the same value is returned for all iSNS clients accessing
the iSNS server. Only query messages may be performed on these
attributes. Attempted registrations of values for these attributes
SHALL return a status code of 3 (Invalid Registration).
A query for an iSNS Server-Specific attribute MUST contain the
identifying key attribute (i.e., iSCSI Name or FC Port Name WWPN) of
the Node originating the registration or query message as the Source
and Message Key attributes. The Operating Attributes are the
server-specific attributes being registered or queried.
Tseng, et al. Standards Track [Page 97]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.9.1. iSNS Server Vendor OUI
This attribute is the OUI (Organizationally Unique Identifier)
[802-1990] identifying the specific vendor implementing the iSNS
server. This attribute can only be queried; iSNS clients SHALL NOT be
allowed to register a value for the iSNS Server Vendor OUI.
6.10. Vendor-Specific Attributes
iSNS server implementations MAY define vendor-specific attributes for
private use. These attributes MAY be used to store optional data
that is registered and/or queried by iSNS clients in order to gain
optional capabilities. Note that any implementation of vendor-
specific attributes in the iSNS server SHALL NOT impose any form of
mandatory behavior on the part of the iSNS client.
The tag values used for vendor-specific and user-specific use are
defined in Section 6.1. To avoid misinterpreting proprietary
attributes, the vendor's own OUI (Organizationally Unique Identifier)
MUST be placed in the upper three bytes of the attribute value field
itself.
The OUI is defined in IEEE Std 802-1990 and is the same constant used
to generate 48 bit Universal LAN MAC addresses. A vendor's own iSNS
implementation will then be able to recognize the OUI in the
attribute field and be able to execute vendor-specific handling of
the attribute.
6.10.1. Vendor-Specific Server Attributes
Attributes with tags in the range 257 to 384 are vendor-specific or
site-specific attributes of the iSNS server. Values for these
attributes are administratively set by the specific vendor providing
the iSNS server implementation. Query access to these attributes may
be administratively controlled. These attributes are unique for each
logical iSNS server instance. Query messages for these attributes
SHALL use the key identifier (i.e., iSCSI Name or FC Port Name WWPN)
for both the Source attribute and Message Key attribute. These
attributes can only be queried; iSNS clients SHALL NOT be allowed to
register a value for server attributes.
6.10.2. Vendor-Specific Entity Attributes
Attributes in the range 385 to 512 are vendor-specific or site-
specific attributes used to describe the Network Entity object.
These attributes are keyed by the Entity Identifier attribute
(tag=1).
Tseng, et al. Standards Track [Page 98]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.10.3. Vendor-Specific Portal Attributes
Attributes in the range 513 to 640 are vendor-specific or site-
specific attributes used to describe the Portal object. These
attributes are keyed by the Portal IP-Address (tag=16) and Portal
TCP/UDP Port (tag=17).
6.10.4. Vendor-Specific iSCSI Node Attributes
Attributes in the range 641 to 768 are vendor-specific or site-
specific attributes used to describe the iSCSI Node object. These
attributes are keyed by the iSCSI Name (tag=32).
6.10.5. Vendor-Specific FC Port Name Attributes
Attributes in the range 769 to 896 are vendor-specific or site-
specific attributes used to describe the N_Port Port Name object.
These attributes are keyed by the FC Port Name WWPN (tag=64).
6.10.6. Vendor-Specific FC Node Name Attributes
Attributes in the range 897 to 1024 are vendor-specific or site-
specific attributes used to describe the FC Node Name object. These
attributes are keyed by the FC Node Name WWNN (tag=96).
6.10.7. Vendor-Specific Discovery Domain Attributes
Attributes in the range 1025 to 1280 are vendor-specific or site-
specific attributes used to describe the Discovery Domain object.
These attributes are keyed by the DD_ID (tag=104).
6.10.8. Vendor-Specific Discovery Domain Set Attributes
Attributes in the range 1281 to 1536 are vendor-specific or site-
specific attributes used to describe the Discovery Domain Set object.
These attributes are keyed by the DD Set ID (tag=101)
6.10.9. Other Vendor-Specific Attributes
Attributes in the range 1537 to 2048 can be used for key and non-key
attributes that describe new vendor-specific objects specific to the
vendor's iSNS server implementation.
Tseng, et al. Standards Track [Page 99]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.11. Discovery Domain Registration Attributes
6.11.1. DD Set ID Keyed Attributes
6.11.1.1. Discovery Domain Set ID (DDS ID)
The DDS ID is an unsigned non-zero integer identifier used in the
iSNS directory database as a key to indicate a Discovery Domain Set
uniquely. A DDS is a collection of Discovery Domains that can be
enabled or disabled by a management station. This value is used as a
key for DDS attribute queries. When a Discovery Domain is
registered, it is initially not in any DDS.
If the iSNS client does not provide a DDS_ID in a DDS registration
request message, the iSNS server SHALL generate a DDS_ID value that
is unique within the iSNS database for that new DDS. The created DDS
ID SHALL be returned in the response message. The DDS ID value of 0
is reserved, and the DDS ID value of 1 is used for the default DDS
(see Section 2.2.2).
6.11.1.2. Discovery Domain Set Symbolic Name
A variable-length UTF-8 encoded NULL-terminated text-based field of
up to 256 bytes. This is a user-readable field used to assist a
network administrator in tracking the DDS function. When a client
registers a DDS symbolic name, the iSNS server SHALL verify it is
unique. If the name is not unique, then the DDS registration SHALL
be rejected with an "Invalid Registration" Status Code. The invalid
attribute(s), in this case the DDS symbolic name, SHALL be included
in the response.
6.11.1.3. Discovery Domain Set Status
The DDS_Status field is a 32-bit bitmap indicating the status of the
DDS. Bit 0 of the bitmap indicates whether the DDS is Enabled (1) or
Disabled (0). The default value for the DDS Enabled flag is Disabled
(0).
Bit Position DDS Status
------------ ---------
31 (Lsb) DDS Enabled (1) / DDS Disabled (0)
All others RESERVED
6.11.1.4. Discovery Domain Set Next ID
This is a virtual attribute containing a 4-byte integer value that
indicates the next available (i.e., unused) Discovery Domain Set
Index value. This attribute may only be queried; the iSNS server
Tseng, et al. Standards Track [Page 100]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
SHALL return an error code of 3 (Invalid Registration) to any client
that attempts to register a value for this attribute. A Message Key
is not required when exclusively querying for this attribute.
The Discovery Domain Set Next Index MAY be used by an SNMP client to
create an entry in the iSNS server. SNMP requirements are described
in Section 2.10.
6.11.2. DD ID Keyed Attributes
6.11.2.1. Discovery Domain ID (DD ID)
The DD ID is an unsigned non-zero integer identifier used in the iSNS
directory database as a key to identify a Discovery Domain uniquely.
This value is used as the key for any DD attribute query. If the
iSNS client does not provide a DD_ID in a DD registration request
message, the iSNS server SHALL generate a DD_ID value that is unique
within the iSNS database for that new DD (i.e., the iSNS client will
be registered in a new DD). The created DD ID SHALL be returned in
the response message. The DD ID value of 0 is reserved, and the DD
ID value of 1 is used for the default DD (see Section 2.2.2).
6.11.2.2. Discovery Domain Symbolic Name
A variable-length UTF-8 encoded NULL-terminated text-based field of
up to 256 bytes. When a client registers a DD symbolic name, the
iSNS server SHALL verify it is unique. If the name is not unique,
then the DD registration SHALL be rejected with an "Invalid
Registration" Status Code. The invalid attribute(s), in this case
the DD symbolic name, SHALL be included in the response.
6.11.2.3. Discovery Domain Member: iSCSI Node Index
This is the iSCSI Node Index of a Storage Node that is a member of
the DD. The DD may have a list of 0 to n members. The iSCSI Node
Index is one alternative representation of membership in a Discovery
Domain, the other alternative being the iSCSI Name. The Discovery
Domain iSCSI Node Index is a 4-byte non-zero integer value.
The iSCSI Node Index can be used to represent a DD member in
situations where the iSCSI Name is too long to be used. An example
of this is when SNMP is used for management, as described in Section
2.10.
The iSCSI Node Index and the iSCSI Name stored as a member in a DD
SHALL be consistent with the iSCSI Node Index and iSCSI Name
attributes registered for the Storage Node object in the iSNS server.
Tseng, et al. Standards Track [Page 101]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
6.11.2.4. Discovery Domain Member: iSCSI Name
A variable-length UTF-8 encoded NULL-terminated text-based field of
up to 224 bytes. It indicates membership for the specified iSCSI
Storage Node in the Discovery Domain. Note that the referenced
Storage Node does not need to be actively registered in the iSNS
database before the iSNS client uses this attribute. There is no
limit to the number of members that may be in a DD. Membership is
represented by the iSCSI Name of the iSCSI Storage Node.
6.11.2.5. Discovery Domain Member: FC Port Name
This 64-bit identifier attribute indicates membership for an iFCP
Storage Node (FC Port) in the Discovery Domain. Note that the
referenced Storage Node does not need to be actively registered in
the iSNS database before the iSNS client uses this attribute. There
is no limit to the number of members that may be in a DD. Membership
is represented by the FC Port Name (WWPN) of the iFCP Storage Node.
6.11.2.6. Discovery Domain Member: Portal Index
This attribute indicates membership in the Discovery Domain for a
Portal. It is an alternative representation for Portal membership to
the Portal IP Address and Portal TCP/UDP Port. The referenced Portal
MUST be actively registered in the iSNS database before the iSNS
client uses this attribute.
6.11.2.7. Discovery Domain Member: Portal IP Address
This attribute and the Portal TCP/UDP Port attribute indicate
membership in the Discovery Domain for the specified Portal. Note
that the referenced Portal does not need to be actively registered in
the iSNS database before the iSNS client uses this attribute.
6.11.2.8. Discovery Domain Member: Portal TCP/UDP Port
This attribute and the Portal IP Address attribute indicate
membership in the Discovery Domain for the specified Portal. Note
that the referenced Portal does not need to be actively registered in
the iSNS database before the iSNS client uses this attribute.
6.11.2.9. Discovery Domain Features
The Discovery Domain Features is a bitmap indicating the features of
this DD. The bit positions are defined below. A bit set to 1
indicates the DD has the corresponding characteristics.
Tseng, et al. Standards Track [Page 102]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Bit Position DD Feature
------------ ----------
31 (Lsb) Boot List Enabled (1)/Boot List Disabled (0)
All others RESERVED
Boot List: this feature indicates that the target(s) in this DD
provides boot capabilities for the member initiators, as described in
[iSCSI-boot].
6.11.2.10. Discovery Domain Next ID
This is a virtual attribute containing a 4-byte integer value that
indicates the next available (i.e., unused) Discovery Domain Index
value. This attribute may only be queried; the iSNS server SHALL
return an error code of 3 (Invalid Registration) to any client that
attempts to register a value for this attribute. A Message Key is
not required when exclusively querying for this attribute.
7. Security Considerations
7.1. iSNS Security Threat Analysis
When the iSNS protocol is deployed, the interaction between iSNS
server and iSNS clients is subject to the following security threats:
a) An attacker could alter iSNS protocol messages, such as to direct
iSCSI and iFCP devices to establish connections with rogue peer
devices, or to weaken/eliminate IPSec protection for iSCSI or
iFCP traffic.
b) An attacker could masquerade as the real iSNS server using false
iSNS heartbeat messages. This could cause iSCSI and iFCP devices
to use rogue iSNS servers.
c) An attacker could gain knowledge about iSCSI and iFCP devices by
snooping iSNS protocol messages. Such information could aid an
attacker in mounting a direct attack on iSCSI and iFCP devices,
such as a denial-of-service attack or outright physical theft.
To address these threats, the following capabilities are needed:
a) Unicast iSNS protocol messages may need to be authenticated. In
addition, to protect against threat c), confidentiality support
is desirable and is REQUIRED when certain functions of iSNS
server are utilized.
Tseng, et al. Standards Track [Page 103]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
b) Multicast iSNS protocol messages such as the iSNS heartbeat
message may need to be authenticated. These messages need not be
confidential since they do not leak critical information.
7.2. iSNS Security Implementation and Usage Requirements
If the iSNS server is used to distribute authorizations for
communications between iFCP and iSCSI peer devices, IPsec ESP with
null transform MUST be implemented, and non-null transform MAY be
implemented. If a non-null transform is implemented, then the DES
encryption algorithm SHOULD NOT be used.
If the iSNS server is used to distribute security policy for iFCP and
iSCSI devices, then authentication, data integrity, and
confidentiality MUST be supported and used. Where confidentiality is
desired or required, IPSec ESP with non-null transform SHOULD be
used, and the DES encryption algorithm SHOULD NOT be used.
If the iSNS server is used to provide the boot list for clients, as
described in Section 6.11.2.9, then the iSCSI boot client SHOULD
implement a secure iSNS connection.
In order to protect against an attacker masquerading as an iSNS
server, client devices MUST support the ability to authenticate
broadcast or multicast messages such as the iSNS heartbeat. The iSNS
authentication block (which is identical in format to the SLP
authentication block) SHALL be used for this purpose. iSNS clients
MUST implement the iSNS authentication block and MUST support BSD
value 0x002. If the iSNS server supports broadcast or multicast iSNS
messages (i.e., the heartbeat), then the server MUST implement the
iSNS authentication block and MUST support BSD value 0x002. Note
that the authentication block is used only for iSNS broadcast or
multicast messages and MUST NOT be used in unicast iSNS messages.
There is no requirement that the communicating identities in iSNS
protocol messages be kept confidential. Specifically, the identity
and location of the iSNS server is not considered confidential.
For protecting unicast iSNS protocol messages, iSNS servers
supporting security MUST implement ESP in tunnel mode and MAY
implement transport mode.
All iSNS implementations supporting security MUST support the replay
protection mechanisms of IPsec.
iSNS security implementations MUST support both IKE Main Mode and
Aggressive Mode for authentication, negotiation of security
associations, and key management, using the IPSec DOI [RFC2407].
Tseng, et al. Standards Track [Page 104]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Manual keying SHOULD NOT be used since it does not provide the
necessary rekeying support. Conforming iSNS security implementations
MUST support authentication using a pre-shared key, and MAY support
certificate-based peer authentication using digital signatures. Peer
authentication using the public key encryption methods outlined in
IKEs Sections 5.2 and 5.3 [RFC2409] SHOULD NOT be supported.
Conforming iSNS implementations MUST support both IKE Main Mode and
Aggressive Mode. IKE Main Mode with pre-shared key authentication
SHOULD NOT be used when either of the peers use dynamically assigned
IP addresses. Although Main Mode with pre-shared key authentication
offers good security in many cases, situations where dynamically
assigned addresses are used force the use of a group pre-shared key,
which is vulnerable to man-in-the-middle attack. IKE Identity
Payload ID_KEY_ID MUST NOT be used.
When digital signatures are used for authentication, either IKE Main
Mode or IKE Aggressive Mode MAY be used. In all cases, access to
locally stored secret information (pre-shared key or private key for
digital signing) MUST be suitably restricted, since compromise of the
secret information nullifies the security properties of the IKE/IPsec
protocols.
When digital signatures are used to achieve authentication, an IKE
negotiator SHOULD use IKE Certificate Request Payload(s) to specify
the certificate authority (or authorities) that are trusted in
accordance with its local policy. IKE negotiators SHOULD check the
pertinent Certificate Revocation List (CRL) before accepting a PKI
certificate for use in IKE's authentication procedures.
When the iSNS server is used without security, IP block storage
protocol implementations MUST support a negative cache for
authentication failures. This allows implementations to avoid
continually contacting discovered endpoints that fail authentication
within IPsec or at the application layer (in the case of iSCSI
Login). The negative cache need not be maintained within the IPsec
implementation, but rather within the IP block storage protocol
implementation.
7.3. Discovering Security Requirements of Peer Devices
Once communication between iSNS clients and the iSNS server has been
secured through use of IPSec, the iSNS client devices have the
capability to discover the security settings that they need to use
for their peer-to-peer communications using the iSCSI and/or iFCP
protocols. This provides a potential scaling advantage over device-
by-device configuration of individual security policies for each
iSCSI and iFCP device.
Tseng, et al. Standards Track [Page 105]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
The iSNS server stores security settings for each iSCSI and iFCP
device interface. These security settings, which can be retrieved by
authorized hosts, include use or non-use of IPSec, IKE, Main Mode,
and Aggressive Mode. For example, IKE may not be enabled for a
particular interface of a peer device. If a peer device can learn of
this in advance by consulting the iSNS server, it will not need to
waste time and resources attempting to initiate an IKE phase 1
session with that peer device interface.
If iSNS is used for this purpose, then the minimum information that
should be learned from the iSNS server is the use or non-use of IKE
and IPSec by each iFCP or iSCSI peer device interface. This
information is encoded in the Security Bitmap field of each Portal of
the peer device, and is applicable on a per-interface basis for the
peer device. iSNS queries for acquiring security configuration data
about peer devices MUST be protected by IPSec/ESP authentication.
7.4. Configuring Security Policies of iFCP/iSCSI Devices
Use of iSNS for distribution of security policies offers the
potential to reduce the burden of manual device configuration, and to
decrease the probability of communications failures due to
incompatible security policies. If iSNS is used to distribute
security policies, then IPSec authentication, data integrity, and
confidentiality MUST be used to protect all iSNS protocol messages.
The complete IKE/IPSec configuration of each iFCP and/or iSCSI device
can be stored in the iSNS server, including policies that are used
for IKE Phase 1 and Phase 2 negotiations between client devices. The
IKE payload format includes a series of one or more proposals that
the iSCSI or iFCP device will use when negotiating the appropriate
IPsec policy to use to protect iSCSI or iFCP traffic.
In addition, the iSCSI Authentication Methods used by each iSCSI
device can also be stored in the iSNS server. The iSCSI AuthMethod
field (tag=42) contains a null-terminated string embedded with the
text values indicating iSCSI authentication methods to be used by
that iSCSI device.
Note that iSNS distribution of security policy is not necessary if
the security settings can be determined by other means, such as
manual configuration or IPsec security policy distribution. If a
network entity has already obtained its security configuration via
other mechanisms, then it MUST NOT request security policy via iSNS.
Tseng, et al. Standards Track [Page 106]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
7.5. Resource Issues
The iSNS protocol is lightweight and will not generate a significant
amount of traffic. iSNS traffic is characterized by occasional
registration, notification, and update messages that do not consume
significant amounts of bandwidth. Even software-based IPSec
implementations should not have a problem handling the traffic loads
generated by the iSNS protocol.
To fulfill iSNS security requirements, the only additional resources
needed beyond what is already required for iSCSI and iFCP involve the
iSNS server. Because iSCSI and iFCP end nodes are already required
to implement IKE and IPSec, these existing requirements can also be
used to fulfill IKE and IPSec requirements for iSNS clients.
7.6. iSNS Interaction with IKE and IPSec
When IPSec security is enabled, each iSNS client with at least one
Storage Node that is registered in the iSNS database SHALL maintain
at least one phase-1 security association with the iSNS server. All
iSNS protocol messages between iSNS clients and the iSNS server SHALL
be protected by a phase-2 security association.
When a Network Entity is removed from the iSNS database, the iSNS
server SHALL send a phase-1 delete message to the associated iSNS
client IKE peer, and tear down all phase-1 and phase-2 SAs associated
with that iSNS client.
8. IANA Considerations
The well-known TCP and UDP port number for iSNS is 3205.
The standards action of this RFC creates two registries to be
maintained by IANA in support of iSNSP and assigns initial values for
both registries. The first registry is of Block Storage Protocols
supported by iSNS. The second registry is a detailed registry of
standard iSNS attributes that can be registered to and queried from
the iSNS server. Note that this RFC uses the registry created for
Block Structure Descriptor (BSD) in Section 15 of Service Location
Protocol, Version 2 [RFC2608].
8.1. Registry of Block Storage Protocols
In order to maintain a registry of block storage protocols supported
by iSNSP, IANA will assign a 32-bit unsigned integer number for each
block storage protocol supported by iSNS. This number is stored in
the iSNS database as the Entity Protocol. The initial set of values
to be maintained by IANA for Entity Protocol is indicated in the
Tseng, et al. Standards Track [Page 107]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
table in Section 6.2.2. Additional values for new block storage
protocols to be supported by iSNS SHALL be assigned by the IPS WG
Chairperson, or by a Designated Expert [RFC2434] appointed by the
IETF Transport Area Director.
8.2. Registry of Standard iSNS Attributes
IANA is responsible for creating and maintaining the Registry of
Standard iSNS Attributes. The initial list of iSNS attributes is
described in Section 6. For each iSNS attribute this information
MUST include, its tag value, the attribute length, and the tag values
for the set of permissible registration and query keys that can be
used for that attribute. The initial list of iSNS attributes to be
maintained by IANA is indicated in Section 6.1.
Additions of new standard attributes to the Registry of Standard iSNS
Attributes SHALL require IETF Consensus [RFC2434]. The RFC required
for this process SHALL specify use of tag values reserved for IANA
allocation in Section 6.1. The RFC SHALL specify as a minimum, the
new attribute tag value, attribute length, and the set of permissible
registration and query keys that can be used for the new attribute.
The RFC SHALL also include a discussion of the reasons for the new
attribute(s) and how the new attribute(s) are to be used.
As part of the process of obtaining IETF Consensus, the proposed RFC
and its supporting documentation SHALL be made available to the IPS
WG mailing list or, if the IPS WG is disbanded at the time, to a
mailing list designated by the IETF Transport Area Director. The
review and comment period SHALL last at least three months before the
IPS WG Chair or a person designated by the IETF Transport Area
Director decides either to reject the proposal or to forward the
draft to the IESG for publication as an RFC. When the specification
is published as an RFC, then IANA will register the new iSNS
attribute(s) and make the registration available to the community.
8.3. Block Structure Descriptor (BSD) Registry
Note that IANA is already responsible for assigning and maintaining
values used for the Block Structure Descriptor for the iSNS
Authentication Block (see Section 5.5). Section 15 of [RFC2608]
describes the process for allocation of new BSD values.
Tseng, et al. Standards Track [Page 108]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
9. Normative References
[iSCSI] Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka, M.,
and E. Zeidner, "Internet Small Computer Systems
Interface (iSCSI)", RFC 3720, April 2004.
[iFCP] Monia, C., Mullendore, R., Travostino, F., Jeong, W.,
and M. Edwards, "iFCP - A Protocol for Internet Fibre
Channel Storage Networking", RFC 4172, September 2005.
[iSNSOption] Monia, C., Tseng, J., and K. Gibbons, The IPv4 Dynamic
Host Configuration Protocol (DHCP) Option for the
Internet Storage Name Service, RFC 4174, September 2005.
[RFC2608] Guttman, E., Perkins, C., Veizades, J., and M. Day,
"Service Location Protocol, Version 2 ", RFC 2608, June
1999.
[iSCSI-SLP] Bakke, M., Hufferd, J., Voruganti, K., Krueger, M., and
T. Sperry, "Finding Internet Small Computer Systems
Interface (iSCSI) Targets and Name Servers by Using
Service Location Protocol version 2 (SLP), RFC 4018,
April 2005.
[iSCSI-boot] Sarkar, P., Missimer, D., and C. Sapuntzakis,
"Bootstrapping Clients using the Internet Samll Computer
System Interface (iSCSI) Protocol", RFC 4173, September
2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[STRINGPREP] Bakke, M., "String Profile for Internet Small Computer
Systems Interface (iSCSI) Names", RFC 3722, April 2004.
[NAMEPREP] Hoffman, P. Nameprep: A Stringprep Profile for
Internationalized Domain Names, July 2002.
[RFC2407] Piper, D., "The Internet IP Security Domain of
Interpretation for ISAKMP", RFC 2407, November 1998.
[RFC2408] Maughan, D., Schertler, M., Schneider, M., and J.
Turner, "Internet Security Association and Key
Management Protocol (ISAKMP)", RFC 2408, November 1998.
[RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange
(IKE)", RFC 2409, November 1998.
Tseng, et al. Standards Track [Page 109]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
[EUI-64] Guidelines for 64-bit Global Identifier (EUI-64)
Registration Authority, May 2001, IEEE
[RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation
List (CRL) Profile", RFC 3279, April 2002.
[RFC3280] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet
X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile", RFC 3280,
April 2002.
[802-1990] IEEE Standards for Local and Metropolitan Area Networks:
Overview and Architecture, Technical Committee on
Computer Communications of the IEEE Computer Society,
May 31, 1990
[FC-FS] Fibre Channel Framing and Signaling Interface, NCITS
Working Draft Project 1331-D
10. Informative References
[iSNSMIB] Gibbons, K., et al., "Definitions of Managed Objects for
iSNS (Internet Storage name Service)", Work in Progress,
July 2003.
[X.509] ITU-T Recommendation X.509 (1997 E): Information
Technology - Open Systems Interconnection - The
Directory: Authentication Framework, June 1997
[FC-GS-4] Fibre Channel Generic Services-4 (work in progress),
NCITS Working Draft Project 1505-D
[RFC1510] Kohl, J. and C. Neuman, "The Kerberos Network
Authentication Service (V5)", RFC 1510, September 1993.
[RFC2025] Adams, C., "The Simple Public-Key GSS-API Mechanism
(SPKM)", RFC 2025, October 1996.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC2945] Wu, T., "The SRP Authentication and Key Exchange
System", RFC 2945, September 2000.
Tseng, et al. Standards Track [Page 110]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
[RFC1994] Simpson, W., "PPP Challenge Handshake Authentication
Protocol (CHAP)", RFC 1994, August 1996.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for
Internet-Standard Management Framework", RFC 3410,
December 2002.
[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC
3411, December 2002.
Tseng, et al. Standards Track [Page 111]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Appendix A: iSNS Examples
A.1. iSCSI Initialization Example
This example assumes an SLP Service Agent (SA) has been implemented
on the iSNS host, and an SLP User Agent (UA) has been implemented on
the iSNS initiator. See [RFC2608] for further details on SAs and
UAs. This example also assumes that the target is configured to use
the iSNS server, and have its access control policy subordinated to
the iSNS server.
A.1.1. Simple iSCSI Target Registration
In this example, a simple target with a single iSCSI name registers
with the iSNS server. The target is represented in the iSNS by an
Entity containing one Storage Node, one Portal, and an implicitly
registered Portal Group that provides a relationship between the
Storage Node and Portal. The target has not been assigned a Fully
Qualified Domain Name (FQDN) by the administrator. In this example,
because a PG object is not explicitly registered, a Portal Group with
a PGT of 1 is implicitly registered. In this example SLP is used to
discover the location of the iSNS Server. An alternative is to use
the iSNS DHCP option [iSNSOption] to discover the iSNS server.
+--------------------------+------------------+-------------------+
| iSCSI Target Device | iSNS Server |Management Station |
+--------------------------+------------------+-------------------+
|Discover iSNS--SLP------->| |/*mgmt station is |
| |<--SLP--iSNS Here:| administratively |
| | 192.0.2.100 | authorized to view|
| | | all DDs. Device |
| DevAttrReg--------->| | NAMEabcd was |
|Src:(tag=32) "NAMEabcd" | | previously placed |
|Key: <none present> | | into DDabcd along |
|Oper Attrs: | | with devpdq and |
|tag=1: NULL | | devrst. |
|tag=2: "iSCSI" | | |
|tag=16: 192.0.2.5 | | |
|tag=17: 5001 | | |
|tag=32: "NAMEabcd" | | |
|tag=33: target | | |
|tag=34: "disk 1" | | |
| |<---DevAttrRegRsp | |
| |SUCCESS | |
| |Key:(tag=1) "isns:0001" |
| |Oper Attrs: | |
| |tag=1: "isns:0001"| |
| |tag=2: "iSCSI" | |
Tseng, et al. Standards Track [Page 112]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
| |tag=16: 192.0.2.5 | |
| |tag=17: 5001 | |
| |tag=32: "NAMEabcd"|/* previously |
| |tag=33: target | placed in a DD */ |
| |tag=34: "disk 1" | |
| | | |
| | SCN-------->| |
| |(or SNMP notification) |
| |dest:(tag=32):"MGMTname1" |
| |time:(tag=4): <current time> |
| |tag=35: "MGT-SCN, OBJ-ADD" |
| |tag=32: "NAMEabcd"| |
| | |<-------SCNRsp |
| DevAttrQry--------->| | |
|Src:(tag=32) "NAMEabcd" | | |
|Key:(tag=33) "initiator" | | |
|Oper Attrs: | | |
|tag=16: NULL | | |
|tag=17: NULL | | |
|tag=32: NULL | | |
|/*Query asks for all initr| | |
|devices' IP address, port |<---DevAttrQryRsp | |
|number, and Name*/ |SUCCESS | |
| |tag=16:192.0.2.1 | |
| |tag=17:50000 | |
| |tag=32:"devpdq" | |
| |tag=16:192.0.2.2 | |
| |tag=17:50000 | |
| |tag=32:"devrst" | |
|/*************************| |<-----DevAttrQry |
|Our target "NAMEabcd" | |src: "MGMTname1" |
|discovers two initiators | key:(tag=32)"NAMEabcd"
|in shared DDs. It will | |Op Attrs: |
|accept iSCSI logins from | |tag=16: NULL |
|these two identified | |tag=17: NULL |
|initiators presented by | |tag=32: NULL |
|iSNS | | |
|*************************/| DevAttrQryRsp--->| |
| |SUCCESS | |
| |tag=16: 192.0.2.5 | |
| |tag=17: 5001 | |
| |tag=32: "NAMEabcd"| |
+--------------------------+------------------+-------------------+
Tseng, et al. Standards Track [Page 113]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
A.1.2. Target Registration and DD Configuration
In this example, a more complex target, with two Storage Nodes and
two Portals using ESI monitoring, registers with the iSNS. This
target has been configured with a Fully Qualified Domain Name (FQDN)
in the DNS servers, and the user wishes to use this identifier for
the device. The target explicitly registers Portal Groups to
describe how each Portal provides access to each Storage Node. One
target Storage Node allows coordinated access through both Portals.
The other Storage Node allows access, but not coordinated access,
through both Portals.
+--------------------------+------------------+-------------------+
| iSCSI Target Device | iSNS Server |Management Station |
+--------------------------+------------------+-------------------+
|Discover iSNS--SLP--> | |/*mgmt station is |
| |<--SLP--iSNS Here:| administratively |
| | 192.0.2.100 | authorized to view|
| DevAttrReg--> | | all DDs */ |
|Src: | | |
|tag=32: "NAMEabcd" | | |
|Msg Key: | | |
|tag=1: "jbod1.example.com"| | |
|Oper Attrs: | | |
|tag=1: "jbod1.example.com"| | |
|tag=2: "iSCSI" | | |
|tag=16: 192.0.2.4 | | |
|tag=17: 5001 | | |
|tag=19: 5 | | |
|tag=20: 5002 | | |
|tag=16: 192.0.2.5 | | |
|tag=17: 5001 | | |
|tag=19: 5 | | |
|tag=20: 5002 | | |
|tag=32: "NAMEabcd" | | |
|tag=33: "Target" | | |
|tag=34: "Storage Array 1" | | |
|tag=51: 10 | | |
|tag=49: 192.0.2.4 | | |
|tag=50: 5001 | | |
|tag=49: 192.0.2.5 | | |
|tag=50: 5001 | | |
|tag=32: "NAMEefgh" | | |
|tag=33: "Target" | | |
|tag=34: "Storage Array 2" |/*****************| |
|tag=51: 20 |jbod1.example.com is |
|tag=49: 192.0.2.4 |now registered in | |
|tag=50: 5001 |iSNS, but is not | |
Tseng, et al. Standards Track [Page 114]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
|tag=51: 30 |in any DD. Therefore, |
|tag=49: 192.0.2.5 |no other devices | |
|tag=50: 5001 |can "see" it. | |
| |*****************/| |
| |<--DevAttrRegRsp | |
| |SUCCESS | |
| |Msg Key: | |
| |tag=1: "jbod1.example.com" |
| |Oper Attrs: | |
| |tag=1: "jbod1.example.com" |
| |tag=2: "iSCSI" | |
| |tag=16: 192.0.2.4 | |
| |tag=17: 5001 | |
| |tag=19: 5 | |
| |tag=20: 5002 | |
| |tag=16: 192.0.2.5 | |
| |tag=17: 5001 | |
| |tag=19: 5 | |
| |tag=20: 5002 | |
| |tag=32: "NAMEabcd"| |
| |tag=33: "Target" | |
| |tag=34: "Storage Array 1" |
| |tag=48: "NAMEabcd"| |
| |tag=49: 192.0.2.4 | |
| |tag=50: 5001 | |
| |tag=51: 10 | |
| |tag=48: "NAMEabcd"| |
| |tag=49: 192.0.2.5 | |
| |tag=50: 5001 | |
| |tag=51: 10 | |
| |tag=32: "NAMEefgh"| |
| |tag=33: "Target" | |
| |tag=34: "Storage Array 2" |
| |tag=43: X.509 cert| |
| |tag=48: "NAMEefgh"| |
| |tag=49: 192.0.2.4 | |
| |tag=50: 5001 | |
| |tag=51: 20 | |
| |tag=48: "NAMEefgh"| |
| |tag=49: 192.0.2.5 | |
| |tag=50: 5001 | |
| |tag=51: 30 | |
| | | |
| | SCN------> | |
| | (or SNMP notification) |
| |dest:(tag=32)"mgmt.example.com" |
| |time:(tag=4): <current time> |
| |tag=35: "MGT-SCN, OBJ-ADD" |
Tseng, et al. Standards Track [Page 115]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
| |tag=32: "NAMEabcd"| |
| |tag=35: "MGT-SCN, OBJ-ADD" |
| |tag=32: "NAMEefgh"| |
| | |<--SCNRsp |
| | |SUCCESS |
| | tag=32:"mgmt.example.com"|
| | | |
| | |<--DevAttrQry |
| | |Src: |
| | tag=32:"mgmt.example.com"
| | |Msg Key: |
| | |tag=32: "NAMEabcd" |
| | |Oper Attrs: |
| | |tag=16: <0-length> |
| | |tag=17: <0-length> |
| | |tag=32: <0-length> |
| | | |
| | DevAttrQryRsp--> | |
| |SUCCESS | |
| |Msg Key: | |
| |tag=32: "NAMEabcd"| |
| |Oper Attrs: | |
| |tag=16: 192.0.2.4 | |
| |tag=17: 5001 | |
| |tag=32:"NAMEabcd" | |
| |tag=16: 192.0.2.5 | |
| |tag=17: 5001 | |
| |tag=32:"NAMEabcd" | |
| | |Src: |
| | tag=32:"mgmt.example.com"
| | |Msg Key: |
| | |tag=32: "NAMEefgh" |
| | |Oper Attrs: |
| | |tag=16: <0-length> |
| | |tag=17: <0-length> |
| | |tag=32: <0-length> |
| | | |
| | DevAttrQryRsp--> | |
| |SUCCESS | |
| |Msg Key: | |
| |tag=32: "NAMEefgh"| |
| |Oper Attrs: | |
| |tag=16: 192.0.2.4 | |
| |tag=17: 5001 | |
| |tag=32:"NAMEefgh" | |
| |tag=16: 192.0.2.5 |/**Mgmt Station ***|
| |tag=17: 5001 |displays device, |
| |tag=32:"NAMEefgh" |the operator decides
Tseng, et al. Standards Track [Page 116]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
| | |to place "NAMEabcd"|
| | |into Domain "DDxyz"|
|/*************************| |******************/|
|Target is now registered | | |
|in iSNS. It is then placed| |<--DDReg |
|in a pre-existing DD with | |Src: |
|DD_ID 123 by a management | tag=32:"mgmt.example.com"
|station. | |Msg Key: |
|*************************/| |tag=2065: 123 |
| | |Oper Attrs: |
| | |tag=2068: "NAMEabcd"
| | DDRegRsp-----> | |
| |SUCCESS | |
| |Msg Key: | |
| |tag=2065: 123 | |
| |Oper Attrs: | |
| |tag=2065: 123 | |
+--------------------------+------------------+-------------------+
A.1.3. Initiator Registration and Target Discovery
The following example illustrates a new initiator registering with
the iSNS, and discovering the target NAMEabcd from the example in
A.1.2.
+--------------------------+------------------+-------------------+
| iSCSI Initiator | iSNS |Management Station |
+--------------------------+------------------+-------------------+
|Discover iSNS--SLP--> | |/*mgmt station is |
| |<--SLP--iSNS Here:| administratively |
| | 192.36.53.1 | authorized to view|
|DevAttrReg--> | | all DDs ********/ |
|Src: | | |
|tag=32: "NAMEijkl" | | |
|Msg Key: | | |
|tag=1: "svr1.example.com" | | |
|Oper Attrs: | | |
|tag=1: "svr1.example.com" | | |
|tag=2: "iSCSI" | | |
|tag=16: 192.20.3.1 |/*****************| |
|tag=17: 5001 |Device not in any | |
|tag=19: 5 |DD, so it is | |
|tag=20: 5002 |inaccessible by | |
|tag=32: "NAMEijkl" |other devices | |
|tag=33: "Initiator" |*****************/| |
|tag=34: "Server1" | | |
|tag=51: 11 | | |
|tag=49: 192.20.3.1 | | |
Tseng, et al. Standards Track [Page 117]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
|tag=50: 5001 | | |
| |<--DevAttrRegRsp | |
| |SUCCESS | |
| |Msg Key: | |
| |tag=1: "svr1.example.com" |
| |Oper Attrs: | |
| |tag=1: "svr1.example.com" |
| |tag=2: "iSCSI" | |
| |tag=16: 192.20.3.1| |
| |tag=17: 5001 | |
| |tag=19: 5 | |
| |tag=20: 5002 | |
| |tag=32: "NAMEijkl"| |
| |tag=33: "Initiator" |
| |tag=34: "Server1" | |
| |tag=48: "NAMEijkl"| |
| |tag=49: 192.20.3.1| |
| |tag=50: 5001 | |
| |tag=51: 11 | |
| | | |
| | SCN------> | |
| | (or SNMP notification) |
| |dest:(tag=32)"mgmt.example.com" |
| |time:(tag=4): <current time> |
| |tag=35: "MGT-SCN, OBJ-ADD" |
| |tag=32: "NAMEijkl"| |
| | | |
| | |<------SCNRsp |
| | |SUCCESS |
| | tag=32:"mgmt.example.com"
| | | |
|SCNReg--> | | |
|Src: | | |
|tag=32: "NAMEijkl" | | |
|Msg Key: | | |
|tag=32: "NAMEijkl" | | |
|Oper Attrs: | | |
|tag=35: <TARG&SELF, OBJ-RMV/ADD/UPD> | |
| |<--SCNRegRsp | |
| |SUCCESS | |
| | | |
| | |<----DevAttrQry |
| | |Src: |
| | tag=32:"mgmt.example.com"
| | |Msg Key: |
| | |tag=32: "NAMEijkl" |
| | |Oper Attrs: |
| | |tag=16: <0-length> |
Tseng, et al. Standards Track [Page 118]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
| | |tag=17: <0-length> |
| | |tag=32: <0-length> |
| | DevAttrQryRsp--->| |
| |SUCCESS | |
| |Msg Key: | |
| |tag=32: "NAMEijkl"| |
| |Oper Attrs: | |
| |tag=16:192.20.3.1 | |
| |tag=17: 5001 | |
| |tag=32:"NAMEijkl" | |
| | |/**Mgmt Station ***|
| | |displays device, the
| | |operator decides to|
| | |place "NAMEijkl" into
| | |pre-existing Disc |
| | |Domain "DDxyz" with|
| | |device NAMEabcd |
| | |******************/|
| | |<--DDReg |
| | |Src: |
| | tag=32:"mgmt.example.com"
| | |Msg Key: |
| | |tag=2065: 123 |
| | |Oper Attrs: |
| | |tag=2068: "NAMEijkl"
| | | |
| | DDRegRsp---->| |
| |SUCCESS | |
| |Msg Key: | |
| |tag=2065: 123 | |
| |Oper Attrs: | |
| |tag=2065: 123 |/******************|
| | |"NAMEijkl" has been|
| | |moved to "DDxyz" |
| | |******************/|
| | SCN------>| |
| |dest:(tag=32)"mgmt.example.com" |
| |time:(tag=4): <current time> |
| |tag=35: <MGT-SCN, DD/DDS-MBR-ADD> |
| |tag=2065: 123 | |
| |tag=2068: "NAMEijkl" |
| | | |
| | |<------SCNRsp |
| | |SUCCESS |
| | tag=32:"mgmt.example.com"
| |<-----SCN | |
| |dest:(tag=32)"NAMEijkl" |
| |time:(tag=4): <current time> |
Tseng, et al. Standards Track [Page 119]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
| |tag=35: <TARG&SELF, OBJ-ADD> |
| |tag=32: "NAMEijkl"| |
| SCNRsp------> | | |
|SUCCESS | | |
|tag=32:"NAMEijkl" | | |
| | | |
| |/*****************| |
| |Note that NAMEabcd| |
| |also receives an | |
| |SCN that NAMEijkl | |
| |is in the same DD | |
| |*****************/| |
| (to "NAMEabcd")|<-----SCN | |
| |dest:(tag=32)"NAMEabcd" |
| |time:(tag=4): <current time> |
| |tag=35: <INIT&SELF, OBJ-ADD> |
| |tag=32: "NAMEijkl"| |
| SCNRsp------> | | |
|SUCCESS | | |
|tag=32:"NAMEabcd" | | |
| | | |
| DevAttrQry----------->| | |
|Src: | | |
|tag=32: "NAMEijkl" | | |
|Msg Key: | | |
|tag=33: "Target" | | |
|Oper Attrs: | | |
|tag=16: <0-length> | | |
|tag=17: <0-length> | | |
|tag=32: <0-length> | | |
|tag=34: <0-length> | | |
|tag=43: <0-length> | | |
|tag=48: <0-length> | | |
|tag=49: <0-length> | | |
|tag=50: <0-length> | | |
|tag=51: <0-length> | | |
| |<--DevAttrQryRsp | |
| |SUCCESS | |
| |Msg Key: | |
| |tag=33:"Target" | |
| |Oper Attrs: | |
| |tag=16: 192.0.2.4 | |
| |tag=17: 5001 | |
| |tag=32: "NAMEabcd"| |
| |tag=34: "Storage Array 1" |
| |tag=16: 192.0.2.5 | |
| |tag=17: 5001 | |
| |tag=32: "NAMEabcd"| |
Tseng, et al. Standards Track [Page 120]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
| |tag=34: "Storage Array 1" |
| |tag=43: X.509 cert| |
| |tag=48: "NAMEabcd"| |
| |tag=49: 192.0.2.4 | |
| |tag=50: 5001 | |
| |tag=51: 10 | |
| |tag=48: "NAMEabcd"| |
| |tag=49: 192.0.2.5 | |
| |tag=50: 5001 | |
| |tag=51: 10 | |
| | | |
|/***The initiator has discovered | |
|the target, and has everything | |
|needed to complete iSCSI login | |
|The same process occurs on the | |
|target side; the SCN prompts the | |
|target to download the list of | |
|authorized initiators from the | |
|iSNS (i.e., those initiators in the | |
|same DD as the target.************/ | |
+--------------------------+------------------+-------------------+
Acknowledgements
Numerous individuals contributed to the creation of this document
through their careful review and submissions of comments and
recommendations. We acknowledge the following persons for their
technical contributions to this document: Mark Bakke (Cisco), John
Hufferd (IBM), Julian Satran (IBM), Kaladhar Voruganti(IBM), Joe Czap
(IBM), John Dowdy (IBM), Tom McSweeney (IBM), Jim Hafner (IBM), Chad
Gregory (Intel), Yaron Klein (Sanrad), Larry Lamers (Adaptec), Jack
Harwood (EMC), David Black (EMC), David Robinson (Sun), Alan Warwick
(Microsoft), Bob Snead (Microsoft), Fa Yoeu (Intransa), Joe White
(McDATA), Charles Monia (McDATA), Larry Hofer (McDATA), Ken Hirata
(Vixel), Howard Hall (Pirus), Malikarjun Chadalapaka (HP), Marjorie
Krueger (HP), Siva Vaddepuri (McDATA), and Vinai Singh (American
Megatrends).
Tseng, et al. Standards Track [Page 121]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Authors' Addresses
Josh Tseng
Riverbed Technology
501 2nd Street, Suite 410
San Francisco, CA 94107
Phone: (650)274-2109
EMail:
[email protected]
Kevin Gibbons
McDATA Corporation
4555 Great America Parkway
Santa Clara, CA 95054-1208
Phone: (408) 567-5765
EMail:
[email protected]
Franco Travostino
Nortel
600 Technology Park Drive
Billerica, MA 01821 USA
Phone: (978) 288-7708
EMail:
[email protected]
Curt du Laney
Rincon Research Corporation
101 North Wilmot Road, Suite 101
Tucson AZ 85711
Phone: (520) 519-4409
EMail:
[email protected]
Joe Souza
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
Phone: (425) 706-3135
EMail:
[email protected]
Tseng, et al. Standards Track [Page 122]
RFC 4171 Internet Storage Name Service (iSNS) September 2005
Full Copyright Statement
Copyright (C) The Internet Society (2005).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
[email protected].
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Tseng, et al. Standards Track [Page 123]
