Network Working Group K. McCloghrie

Network Working Group K. McCloghrie
Request for Comments: 2037 A. Bierman
Category: Standards Track Cisco Systems
October 1996

Entity MIB using SMIv2

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.

Table of Contents

1. Introduction .............................................. 2
2. The SNMP Network Management Framework ..................... 2
2.1 Object Definitions ....................................... 2
3. Overview .................................................. 3
3.1 Terms .................................................... 4
3.2 Relationship to Community Strings ........................ 5
3.3 Relationship to Proxy Mechanisms ......................... 5
3.4 Relationship to a Chassis MIB ............................ 5
3.5 Relationship to the Interfaces MIB ....................... 6
3.6 Relationship to the Other MIBs ........................... 6
3.7 Relationship to Naming Scopes ............................ 6
3.8 Multiple Instances of the Entity MIB ..................... 7
3.9 Re-Configuration of Entities ............................. 7
3.10 MIB Structure ........................................... 7
3.10.1 entityPhysical Group .................................. 8
3.10.2 entityLogical Group ................................... 8
3.10.3 entityMapping Group ................................... 8
3.10.4 entityGeneral Group ................................... 9
3.10.5 entityNotifications Group ............................. 9
3.11 Multiple Agents ......................................... 9
4. Definitions ............................................... 10
5. Usage Examples ............................................ 26
5.1 Router/Bridge ............................................ 26
5.2 Repeaters ................................................ 30
6. Acknowledgements .......................................... 33
7. References ................................................ 34
8. Security Considerations ................................... 35
9. Authors' Addresses ........................................ 35

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RFC 2037 Entity MIB using SMIv2 October 1996

1. Introduction

This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
In particular, it describes managed objects used for managing
multiple logical and physical entities managed by a single SNMP
agent.

2. The SNMP Network Management Framework

The SNMP Network Management Framework presently consists of three
major components. They are:

o the SMI, described in RFC 1902 [1], - the mechanisms used for
describing and naming objects for the purpose of management.

o the MIB-II, STD 17, RFC 1213 [2], - the core set of managed
objects for the Internet suite of protocols.

o the protocol, RFC 1157 [6] and/or RFC 1905 [4], - the protocol
for accessing managed information.

Textual conventions are defined in RFC 1903 [3], and conformance
statements are defined in RFC 1904 [5].

The Framework permits new objects to be defined for the purpose of
experimentation and evaluation.

This memo specifies a MIB module that is compliant to the SNMPv2 SMI.
A semantically identical MIB conforming to the SNMPv1 SMI can be
produced through the appropriate translation.

2.1. Object Definitions

Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the subset of Abstract Syntax Notation One (ASN.1)
defined in the SMI. In particular, each object type is named by an
OBJECT IDENTIFIER, an administratively assigned name. The object
type together with an object instance serves to uniquely identify a
specific instantiation of the object. For human convenience, we
often use a textual string, termed the descriptor, to refer to the
object type.

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3. Overview

There is a need for a standardized way of representing a single agent
which supports multiple instances of one MIB. This is presently true
for at least 3 standard MIBs, and is likely to become true for more
and more MIBs as time passes. For example:

- multiple instances of a bridge supported within a single
device having a single agent;

- multiple repeaters supported by a single agent;

- multiple OSPF backbone areas, each one operating as part
of its own Autonomous System, and each identified by the
same area-id (e.g., 0.0.0.0), supported inside a single
router with one agent.

The fact that it is a single agent in each of these cases implies
there is some relationship which binds all of these entities
together. Effectively, there is some "overall" physical entity which
houses the sum of the things managed by that one agent, i.e., there
are multiple "logical" entities within a single physical entity.
Sometimes, the overall physical entity contains multiple (smaller)
physical entities and each logical entity is associated with a
particular physical entity. Sometimes, the overall physical entity
is a "compound" of multiple physical entities (e.g., a stack of
stackable hubs).

What is needed is a way to determine exactly what logical entities
are managed by the agent (either by SNMPv1 or SNMPv2), and thereby to
be able to communicate with the agent about a particular logical
entity. When different logical entities are associated with
different physical entities within the overall physical entity, it is
also useful to be able to use this information to distinguish between
logical entities.

In these situations, there is no need for varbinds for multiple
logical entities to be referenced in the same SNMP message (although
that might be useful in the future). Rather, it is sufficient, and
in some situations preferable, to have the context/community in the
message identify the logical entity to which the varbinds apply.

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3.1. Terms

Some new terms are used throughout this document:

- Naming Scope
A "naming scope" represents the set of information that may be
potentially accessed through a single SNMP operation. All instances
within the naming scope share the same unique identifier space. For
SNMPv1, a naming scope is identified by the value of the associated
'entLogicalCommunity' instance.

- Multi-Scoped Object
A MIB object, for which identical instance values identify
different managed information in different naming scopes, is called
a "multi-scoped" MIB object.

- Single-Scoped Object
A MIB object, for which identical instance values identify the same
managed information in different naming scopes, is called a
"single-scoped" MIB object.

- Logical Entity
A managed system contains one or more logical entities, each
represented by at most one instantiation of each of a particular
set of MIB objects. A set of management functions is associated
with each logical entity. Examples of logical entities include
routers, bridges, print-servers, etc.

- Physical Entity
A "physical entity" or "physical component" represents an
identifiable physical resource within a managed system. Zero or
more logical entities may utilize a physical resource at any given
time. It is an implementation-specific manner as to which physical
components are represented by an agent in the EntPhysicalTable.
Typically, physical resources (e.g. communications ports,
backplanes, sensors, daughter-cards, power supplies, the overall
chassis) which can be managed via functions associated with one or
more logical entities are included in the MIB.

- Containment Tree
Each physical component may optionally be modeled as 'contained'
within another physical component. A "containment-tree" is the
conceptual sequence of entPhysicalIndex values which uniquely
specifies the exact physical location of a physical component
within the managed system. It is generated by 'following and
recording' each 'entPhysicalContainedIn' instance 'up the tree
towards the root', until a value of zero indicating no further
containment is found.

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Note that chassis slots, which are capable of accepting one or more
module types from one or more vendors, are modeled as containers in
this MIB. The value of entPhysicalContainedIn for a particular
'module' entity (entPhysicalClass value of 'module(9)') must be
equal to an entPhysicalIndex that represents the parent 'container'
entity (associated entPhysicalClass value of ('container(5)'). An
agent must represent both empty and full containers in the
entPhysicalTable.

3.2. Relationship to Community Strings

For community-based SNMP, distinguishing between different logical
entities is one (but not the only) purpose of the community string
[6]. This is accommodated by representing each community string as a
logical entity.

Note that different logical entities may share the same naming scope
(and therefore the same values of entLogicalCommunity). This is
possible, providing they have no need for the same instance of a MIB
object to represent different managed information.

3.3. Relationship to Proxy Mechanisms

The Entity MIB is designed to allow functional component discovery.
The administrative relationships between different logical entities
are not visible in any Entity MIB tables. An NMS cannot determine
whether MIB instances in different naming scopes are realized locally
or remotely (e.g. via some proxy mechanism) by examining any
particular Entity MIB objects.

The management of administrative framework functions is not an
explicit goal of the Entity MIB WG at this time. This new area of
functionality may be revisited after some operational experience with
the Entity MIB is gained.

Note that a network administrator will likely be able to associate
community strings with naming scopes with proprietary mechanisms, as
a matter of configuration. There are no mechanisms for managing
naming scopes defined in this MIB.

3.4. Relationship to a Chassis MIB

Some readers may recall that a previous IETF working group attempted
to define a Chassis MIB. No consensus was reached by that working
group, possibly because its scope was too broad. As such, it is not
the purpose of this MIB to be a "Chassis MIB replacement", nor is it
within the scope of this MIB to contain all the information which
might be necessary to manage a "chassis". On the other hand, the

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entities represented by an implementation of this MIB might well be
contained in a chassis.

3.5. Relationship to the Interfaces MIB

The Entity MIB contains a mapping table identifying physical
components that have 'external values' (e.g. ifIndex) associated with
them within a given naming scope. This table can be used to identify
the physical location of each interface in the ifTable [7]. Since
ifIndex values in different contexts are not related to one another,
the interface to physical component associations are relative to the
same logical entity within the agent.

The Entity MIB also contains an 'entPhysicalName' object, which
approximates the semantics of the ifName object from the Interfaces
MIB [7] for all types of physical components.

3.6. Relationship to the Other MIBs

The Entity MIB contains a mapping table identifying physical
components that have identifiers from other standard MIBs associated
with them. For example, this table can be used along with the
physical mapping table to identify the physical location of each
repeater port in the rptrPortTable, or each interface in the ifTable.

3.7. Relationship to Naming Scopes

There is some question as to which MIB objects may be returned within
a given naming scope. MIB objects which are not multi-scoped within a
managed system are likely to ignore context information in
implementation. In such a case, it is likely such objects will be
returned in all naming scopes (e.g. not just the 'main' naming
scope).

For example, a community string used to access the management
information for logical device 'bridge2' may allow access to all the
non-bridge related objects in the 'main' naming scope, as well as a
second instance of the Bridge MIB.

It is an implementation-specific matter as to the isolation of
single-scoped MIB objects by the agent. An agent may wish to limit
the objects returned in a particular naming scope to just the multi-
scoped objects in that naming scope (e.g. system group and the Bridge
MIB). In this case, all single-scoped management information would
belong to a common naming scope (e.g. 'main'), which itself may
contain some multi-scoped objects (e.g. system group).

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3.8. Multiple Instances of the Entity MIB

It is possible that more than one agent exists in a managed system,
and in such cases, multiple instances of the Entity MIB (representing
the same managed objects) may be available to an NMS.

In order to reduce complexity for agent implementation, multiple
instances of the Entity MIB are not required to be equivalent or even
consistent. An NMS may be able to 'align' instances returned by
different agents by examining the columns of each table, but vendor-
specific identifiers and (especially) index values are likely to be
different. Each agent may be managing different subsets of the entire
chassis as well.

When all of a physically-modular device is represented by a single
agent, the entry for which entPhysicalContainedIn has the value zero
would likely have 'chassis' as the value of its entPhysicalClass;
alternatively, for an agent on a module where the agent represents
only the physical entities on that module (not those on other
modules), the entry for which entPhysicalContainedIn has the value
zero would likely have 'module' as the value of its entPhysicalClass.

An agent implementation of the entLogicalTable is not required to
contain information about logical entities managed primarily by other
agents. That is, the entLogicalTAddress and entLogicalTDomain objects
in the entLogicalTable are provided to support an historical
multiplexing mechanism, not to identify other SNMP agents.

Note that the Entity MIB is a single-scoped MIB, in the event an
agent represents the MIB in different naming scopes.

3.9. Re-Configuration of Entities

All the MIB objects defined in this MIB have at most a read-only
MAX-ACCESS clause, i.e., none are write-able. This is a conscious
decision by the working group to limit this MIB's scope. It is
possible that this restriction could be lifted after implementation
experience, by means of additional tables (using the AUGMENTS clause)
for configuration and extended entity information.

3.10. MIB Structure

The Entity MIB contains five conformance groups:

- entityPhysical group
Describes the physical entities managed by a single agent.

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- entityLogical group
Describes the logical entities managed by a single agent.

- entityMapping group
Describes the associations between the physical entities,
logical entities, interfaces, and non-interface ports managed
by a single agent.

-entityGeneral group
Describes general system attributes shared by potentially
all types of entities managed by a single agent.

-entityNotifications group
Contains status indication notifications.

3.10.1. entityPhysical Group

This group contains a single table to identify physical system
components, called the entPhysicalTable.

The entPhysicalTable contains one row per physical entity, and must
always contains at least one row for an "overall" physical entity.
Each row is indexed by an arbitrary, small integer, and contains a
description and type of the physical entity. It also optionally
contains the index number of another entPhysicalEntry indicating a
containment relationship between the two.

3.10.2. entityLogical Group

This group contains a single table to identify logical entities,
called the entLogicalTable.

The entLogicalTable contains one row per logical entity. Each row is
indexed by an arbitrary, small integer and contains a name,
description, and type of the logical entity. It also contains
information to allow SNMPv1 or SNMPv2C [9] access to the MIB
information for the logical entity.

3.10.3. entityMapping Group

This group contains a three tables to identify associations between
different system components.

The entLPMappingTable contains mappings between entLogicalIndex
values (logical entities) and entPhysicalIndex values (the physical
components supporting that entity). A logical entity can map to more
than one physical component, and more than one logical entity can map
to (share) the same physical component.

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The entAliasMappingTable contains mappings between entLogicalIndex,
entPhysicalIndex pairs and 'alias' object identifier values. This
allows resources managed with other MIBs (e.g. repeater ports, bridge
ports, physical and logical interfaces) to be identified in the
physical entity hierarchy. Note that each alias identifier is only
relevant in a particular naming scope.

The entPhysicalContainsTable contains simple mappings between
'entPhysicalContainedIn' values for each container/containee
relationship in the managed system. The indexing of this table allows
an NMS to quickly discover the 'entPhysicalIndex' values for all
children of a given physical entity.

3.10.4. entityGeneral Group

This group contains general information relating to the other object
groups.

At this time, the entGeneral group contains a single scalar object
(entLastChangeTime), which represents the value of sysUptime when any
part of the system configuration last changed.

3.10.5. entityNotifications Group

This group contains notification definitions relating to the overall
status of the Entity MIB instantiation.

3.11. Multiple Agents

Even though a primary motivation for this MIB is to represent the
multiple logical entities supported by a single agent, it is also
possible to use it to represent multiple logical entities supported
by multiple agents (in the same "overall" physical entity). Indeed,
it is implicit in the SNMP architecture, that the number of agents is
transparent to a network management station.

However, there is no agreement at this time as to the degree of
cooperation which should be expected for agent implementations.
Therefore, multiple agents within the same managed system are free to
implement the Entity MIB independently. (Refer the section on
"Multiple Instances of the Entity MIB" for more details).

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4. Definitions

ENTITY-MIB DEFINITIONS ::= BEGIN

IMPORTS
MODULE-IDENTITY, OBJECT-TYPE,
mib-2, NOTIFICATION-TYPE
FROM SNMPv2-SMI
TDomain, TAddress, DisplayString, TEXTUAL-CONVENTION,
AutonomousType, RowPointer, TimeStamp
FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP
FROM SNMPv2-CONF;

entityMIB MODULE-IDENTITY
LAST-UPDATED "9605160000Z"
ORGANIZATION "IETF ENTMIB Working Group"
CONTACT-INFO
" WG E-mail: [email protected]
Subscribe: [email protected]
msg body: subscribe entmib

Keith McCloghrie
ENTMIB Working Group Chair
Cisco Systems Inc.
170 West Tasman Drive
San Jose, CA 95134
408-526-5260
[email protected]

Andy Bierman
ENTMIB Working Group Editor
Cisco Systems Inc.
170 West Tasman Drive
San Jose, CA 95134
408-527-3711
[email protected]"
DESCRIPTION
"The MIB module for representing multiple logical
entities supported by a single SNMP agent."
::= { mib-2 47 }

entityMIBObjects OBJECT IDENTIFIER ::= { entityMIB 1 }

-- MIB contains four groups

entityPhysical OBJECT IDENTIFIER ::= { entityMIBObjects 1 }
entityLogical OBJECT IDENTIFIER ::= { entityMIBObjects 2 }

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entityMapping OBJECT IDENTIFIER ::= { entityMIBObjects 3 }
entityGeneral OBJECT IDENTIFIER ::= { entityMIBObjects 4 }

-- Textual Conventions
PhysicalIndex ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"An arbitrary value which uniquely identifies the physical
entity. The value is a small positive integer; index values
for different physical entities are not necessarily
contiguous."
SYNTAX INTEGER (1..2147483647)

PhysicalClass ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"An enumerated value which provides an indication of the
general hardware type of a particular physical entity."
SYNTAX INTEGER {
other(1),
unknown(2),
chassis(3),
backplane(4),
container(5), -- e.g. slot or daughter-card holder
powerSupply(6),
fan(7),
sensor(8),
module(9), -- e.g. plug-in card or daughter-card
port(10)
}

-- The Physical Entity Table

entPhysicalTable OBJECT-TYPE
SYNTAX SEQUENCE OF EntPhysicalEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table contains one row per physical entity. There is
always at least one row for an 'overall' physical entity."
::= { entityPhysical 1 }

entPhysicalEntry OBJECT-TYPE
SYNTAX EntPhysicalEntry
MAX-ACCESS not-accessible
STATUS current

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DESCRIPTION
"Information about a particular physical entity.

Each entry provides objects (entPhysicalDescr,
entPhysicalVendorType, and entPhysicalClass) to help an NMS
identify and characterize the entry, and objects
(entPhysicalContainedIn and entPhysicalParentRelPos) to help
an NMS relate the particular entry to other entries in this
table."
INDEX { entPhysicalIndex }
::= { entPhysicalTable 1 }

EntPhysicalEntry ::= SEQUENCE {
entPhysicalIndex PhysicalIndex,
entPhysicalDescr DisplayString,
entPhysicalVendorType AutonomousType,
entPhysicalContainedIn INTEGER,
entPhysicalClass PhysicalClass,
entPhysicalParentRelPos INTEGER,
entPhysicalName DisplayString
}

entPhysicalIndex OBJECT-TYPE
SYNTAX PhysicalIndex
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The index for this entry."
::= { entPhysicalEntry 1 }

entPhysicalDescr OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A textual description of physical entity. This object
should contain a string which identifies the manufacturer's
name for the physical entity, and should be set to a
distinct value for each version or model of the physical
entity. "
::= { entPhysicalEntry 2 }

entPhysicalVendorType OBJECT-TYPE
SYNTAX AutonomousType
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An indication of the vendor-specific hardware type of the

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physical entity. Note that this is different from the
definition of MIB-II's sysObjectID.

An agent should set this object to a enterprise-specific
registration identifier value indicating the specific
equipment type in detail. The associated instance of
entPhysicalClass is used to indicate the general type of
hardware device.

If no vendor-specific registration identifier exists for
this physical entity, or the value is unknown by this agent,
then the value { 0 0 } is returned."
::= { entPhysicalEntry 3 }

entPhysicalContainedIn OBJECT-TYPE
SYNTAX INTEGER (0..2147483647)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of entPhysicalIndex for the physical entity which
'contains' this physical entity. A value of zero indicates
this physical entity is not contained in any other physical
entity. Note that the set of 'containment' relationships
define a strict hierarchy; that is, recursion is not
allowed."
::= { entPhysicalEntry 4 }

entPhysicalClass OBJECT-TYPE
SYNTAX PhysicalClass
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An indication of the general hardware type of the physical
entity.

An agent should set this object to the standard enumeration
value which most accurately indicates the general class of
the physical entity, or the primary class if there is more
than one.

If no appropriate standard registration identifier exists
for this physical entity, then the value 'other(1)' is
returned. If the value is unknown by this agent, then the
value 'unknown(2)' is returned."
::= { entPhysicalEntry 5 }

entPhysicalParentRelPos OBJECT-TYPE
SYNTAX INTEGER (-1..2147483647)

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MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An indication of the relative position of this 'child'
component among all its 'sibling' components. Sibling
components are defined as entPhysicalEntries which share the
same instance values of each of the entPhysicalContainedIn
and entPhysicalClass objects.

An NMS can use this object to identify the relative ordering
for all sibling components of a particular parent
(identified by the entPhysicalContainedIn instance in each
sibling entry).

This value should match any external labeling of the
physical component if possible. For example, for a module
labeled as 'card #3', entPhysicalParentRelPos should have
the value '3'.

If the physical position of this component does not match
any external numbering or clearly visible ordering, then
user documentation or other external reference material
should be used to determine the parent-relative position. If
this is not possible, then the the agent should assign a
consistent (but possibly arbitrary) ordering to a given set
of 'sibling' components, perhaps based on internal
representation of the components.

If the agent cannot determine the parent-relative position
for some reason, or if the associated value of
entPhysicalContainedIn is '0', then the value '-1' is
returned. Otherwise a non-negative integer is returned,
indicating the parent-relative position of this physical
entity.

Parent-relative ordering normally starts from '1' and
continues to 'N', where 'N' represents the highest
positioned child entity. However, if the physical entities
(e.g. slots) are labeled from a starting position of zero,
then the first sibling should be associated with a
entPhysicalParentRelPos value of '0'. Note that this
ordering may be sparse or dense, depending on agent
implementation.

The actual values returned are not globally meaningful, as
each 'parent' component may use different numbering
algorithms. The ordering is only meaningful among siblings
of the same parent component.

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The agent should retain parent-relative position values
across reboots, either through algorithmic assignment or use
of non-volatile storage."
::= { entPhysicalEntry 6 }

entPhysicalName OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The textual name of the physical entity. The value of this
object should be the name of the component as assigned by
the local device and should be suitable for use in commands
entered at the device's `console'. This might be a text
name, such as `console' or a simple component number (e.g.
port or module number), such as `1', depending on the
physical component naming syntax of the device.

If there is no local name, or this object is otherwise not
applicable, then this object contains a zero-length string.

Note that the value of entPhysicalName for two physical
entities will be the same in the event that the console
interface does not distinguish between them, e.g., slot-1
and the card in slot-1."
::= { entPhysicalEntry 7 }

-- The Logical Entity Table
entLogicalTable OBJECT-TYPE
SYNTAX SEQUENCE OF EntLogicalEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table contains one row per logical entity. At least
one entry must exist."
::= { entityLogical 1 }

entLogicalEntry OBJECT-TYPE
SYNTAX EntLogicalEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information about a particular logical entity. Entities
may be managed by this agent or other SNMP agents (possibly)
in the same chassis."
INDEX { entLogicalIndex }
::= { entLogicalTable 1 }

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EntLogicalEntry ::= SEQUENCE {
entLogicalIndex INTEGER,
entLogicalDescr DisplayString,
entLogicalType AutonomousType,
entLogicalCommunity OCTET STRING,
entLogicalTAddress TAddress,
entLogicalTDomain TDomain
}

entLogicalIndex OBJECT-TYPE
SYNTAX INTEGER (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The value of this object uniquely identifies the logical
entity. The value is a small positive integer; index values
for different logical entities are are not necessarily
contiguous."
::= { entLogicalEntry 1 }

entLogicalDescr OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A textual description of the logical entity. This object
should contain a string which identifies the manufacturer's
name for the logical entity, and should be set to a distinct
value for each version of the logical entity. "
::= { entLogicalEntry 2 }

entLogicalType OBJECT-TYPE
SYNTAX AutonomousType
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An indication of the type of logical entity. This will
typically be the OBJECT IDENTIFIER name of the node in the
SMI's naming hierarchy which represents the major MIB
module, or the majority of the MIB modules, supported by the
logical entity. For example:
a logical entity of a regular host/router -> mib-2
a logical entity of a 802.1d bridge -> dot1dBridge
a logical entity of a 802.3 repeater -> snmpDot3RptrMgmt
If an appropriate node in the SMI's naming hierarchy cannot
be identified, the value 'mib-2' should be used."
::= { entLogicalEntry 3 }

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entLogicalCommunity OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (1..255))
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An SNMPv1 or SNMPv2C community-string which can be used to
access detailed management information for this logical
entity. The agent should allow read access with this
community string (to an appropriate subset of all managed
objects) and may also choose to return a community string
based on the privileges of the request used to read this
object. Note that an agent may choose to return a community
string with read-only privileges, even if this object is
accessed with a read-write community string. However, the
agent must take care not to return a community string which
allows more privileges than the community string used to
access this object.

A compliant SNMP agent may wish to conserve naming scopes by
representing multiple logical entities in a single 'main'
naming scope. This is possible when the logical entities
represented by the same value of entLogicalCommunity have no
object instances in common. For example, 'bridge1' and
'repeater1' may be part of the main naming scope, but at
least one additional community string is needed to represent
'bridge2' and 'repeater2'.

Logical entities 'bridge1' and 'repeater1' would be
represented by sysOREntries associated with the 'main'
naming scope.

For agents not accessible via SNMPv1 or SNMPv2C, the value
of this object is the empty-string."
::= { entLogicalEntry 4 }

entLogicalTAddress OBJECT-TYPE
SYNTAX TAddress
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The transport service address by which the logical entity
receives network management traffic, formatted according to
the corresponding value of entLogicalTDomain.

For snmpUDPDomain, a TAddress is 6 octets long, the initial
4 octets containing the IP-address in network-byte order and
the last 2 containing the UDP port in network-byte order.
Consult 'Transport Mappings for Version 2 of the Simple

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Network Management Protocol' (RFC 1906 [8]) for further
information on snmpUDPDomain."
::= { entLogicalEntry 5 }

entLogicalTDomain OBJECT-TYPE
SYNTAX TDomain
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Indicates the kind of transport service by which the
logical entity receives network management traffic.
Possible values for this object are presently found in the
Transport Mappings for SNMPv2 document (RFC 1906 [8])."
::= { entLogicalEntry 6 }

entLPMappingTable OBJECT-TYPE
SYNTAX SEQUENCE OF EntLPMappingEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table contains zero or more rows of logical entity to
physical equipment associations. For each logical entity
known by this agent, there are zero or more mappings to the
physical resources which are used to realize that logical
entity.

An agent should limit the number and nature of entries in
this table such that only meaningful and non-redundant
information is returned. For example, in a system which
contains a single power supply, mappings between logical
entities and the power supply are not useful and should not
be included.

Also, only the most appropriate physical component which is
closest to the root of a particular containment tree should
be identified in an entLPMapping entry.

For example, suppose a bridge is realized on a particular
module, and all ports on that module are ports on this
bridge. A mapping between the bridge and the module would be
useful, but additional mappings between the bridge and each
of the ports on that module would be redundant (since the
entPhysicalContainedIn hierarchy can provide the same
information). If, on the other hand, more than one bridge
was utilizing ports on this module, then mappings between
each bridge and the ports it used would be appropriate.

Also, in the case of a single backplane repeater, a mapping

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for the backplane to the single repeater entity is not
necessary."
::= { entityMapping 1 }

entLPMappingEntry OBJECT-TYPE
SYNTAX EntLPMappingEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information about a particular logical entity to physical
equipment association. Note that the nature of the
association is not specifically identified in this entry. It
is expected that sufficient information exists in the MIBs
used to manage a particular logical entity to infer how
physical component information is utilized."
INDEX { entLogicalIndex, entLPPhysicalIndex }
::= { entLPMappingTable 1 }

EntLPMappingEntry ::= SEQUENCE {
entLPPhysicalIndex PhysicalIndex
}

entLPPhysicalIndex OBJECT-TYPE
SYNTAX PhysicalIndex
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of this object identifies the index value of a
particular entPhysicalEntry associated with the indicated
entLogicalEntity."
::= { entLPMappingEntry 1 }

-- logical entity/component to alias table
entAliasMappingTable OBJECT-TYPE
SYNTAX SEQUENCE OF EntAliasMappingEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table contains zero or more rows, representing
mappings of logical entity and physical component to
external MIB identifiers. Each physical port in the system
may be associated with a mapping to an external identifier,
which itself is associated with a particular logical
entity's naming scope. A 'wildcard' mechanism is provided to
indicate that an identifier is associated with more than one
logical entity."
::= { entityMapping 2 }

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entAliasMappingEntry OBJECT-TYPE
SYNTAX EntAliasMappingEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information about a particular physical equipment, logical
entity to external identifier binding. Each logical
entity/physical component pair may be associated with one
alias mapping. The logical entity index may also be used as
a 'wildcard' (refer to the entAliasLogicalIndexOrZero object
DESCRIPTION clause for details.)

Note that only entPhysicalIndex values which represent
physical ports (i.e. associated entPhysicalClass value is
'port(10)') are permitted to exist in this table."
INDEX { entPhysicalIndex, entAliasLogicalIndexOrZero }
::= { entAliasMappingTable 1 }

EntAliasMappingEntry ::= SEQUENCE {
entAliasLogicalIndexOrZero INTEGER,
entAliasMappingIdentifier RowPointer
}

entAliasLogicalIndexOrZero OBJECT-TYPE
SYNTAX INTEGER (0..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The value of this object uniquely identifies the logical
entity which defines the naming scope for the associated
instance of the 'entAliasMappingIdentifier' object.

If this object has a non-zero value, then it identifies the
logical entity named by the same value of entLogicalIndex.

If this object has a value of zero, then the mapping between
the physical component and the alias identifier for this
entAliasMapping entry is associated with all unspecified
logical entities. That is, a value of zero (the default
mapping) identifies any logical entity which does not have
an explicit entry in this table for a particular
entPhysicalIndex/entAliasMappingIdentifier pair.

For example, to indicate that a particular interface (e.g.
physical component 33) is identified by the same value of
ifIndex for all logical entities, the following instance
might exist:

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entAliasMappingIdentifier.33.0 = ifIndex.5

In the event an entPhysicalEntry is associated differently
for some logical entities, additional entAliasMapping
entries may exist, e.g.:

entAliasMappingIdentifier.33.0 = ifIndex.6
entAliasMappingIdentifier.33.4 = ifIndex.1
entAliasMappingIdentifier.33.5 = ifIndex.1
entAliasMappingIdentifier.33.10 = ifIndex.12

Note that entries with non-zero entAliasLogicalIndexOrZero
index values have precedence over any zero-indexed entry. In
this example, all logical entities except 4, 5, and 10,
associate physical entity 33 with ifIndex.6."
::= { entAliasMappingEntry 1 }

entAliasMappingIdentifier OBJECT-TYPE
SYNTAX RowPointer
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of this object identifies a particular conceptual
row associated with the indicated entPhysicalIndex and
entLogicalIndex pair.

Since only physical ports are modeled in this table, only
entries which represent interfaces or ports are allowed. If
an ifEntry exists on behalf of a particular physical port,
then this object should identify the associated 'ifEntry'.
For repeater ports, the appropriate row in the
'rptrPortGroupTable' should be identified instead.

For example, suppose a physical port was represented by
entPhysicalEntry.3, entLogicalEntry.15 existed for a
repeater, and entLogicalEntry.22 existed for a bridge. Then
there might be two related instances of
entAliasMappingIdentifier:
entAliasMappingIdentifier.3.15 == rptrPortGroupIndex.5.2
entAliasMappingIdentifier.3.22 == ifIndex.17
It is possible that other mappings (besides interfaces and
repeater ports) may be defined in the future, as required.

Bridge ports are identified by examining the Bridge MIB and
appropriate ifEntries associated with each 'dot1dBasePort',
and are thus not represented in this table."
::= { entAliasMappingEntry 2 }

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-- physical mapping table
entPhysicalContainsTable OBJECT-TYPE
SYNTAX SEQUENCE OF EntPhysicalContainsEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A table which exposes the container/containee relationships
between physical entities. This table provides equivalent
information found by constructing the virtual containment
tree for a given entPhysicalTable but in a more direct
format."
::= { entityMapping 3 }

entPhysicalContainsEntry OBJECT-TYPE
SYNTAX EntPhysicalContainsEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A single container/containee relationship."
INDEX { entPhysicalIndex, entPhysicalChildIndex }
::= { entPhysicalContainsTable 1 }

EntPhysicalContainsEntry ::= SEQUENCE {
entPhysicalChildIndex PhysicalIndex
}

entPhysicalChildIndex OBJECT-TYPE
SYNTAX PhysicalIndex
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of entPhysicalIndex for the contained physical
entity."
::= { entPhysicalContainsEntry 1 }

-- last change time stamp for the whole MIB
entLastChangeTime OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time any of these events
occur:
* a conceptual row is created or deleted in any
of these tables:
- entPhysicalTable
- entLogicalTable
- entLPMappingTable

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- entAliasMappingTable
- entPhysicalContainsTable

* any instance in the following list of objects
changes value:
- entPhysicalDescr
- entPhysicalVendorType
- entPhysicalContainedIn
- entPhysicalClass
- entPhysicalParentRelPos
- entPhysicalName
- entLogicalDescr
- entLogicalType
- entLogicalCommunity
- entLogicalTAddress
- entLogicalTDomain
- entAliasMappingIdentifier "
::= { entityGeneral 1 }

-- Entity MIB Trap Definitions
entityMIBTraps OBJECT IDENTIFIER ::= { entityMIB 2 }
entityMIBTrapPrefix OBJECT IDENTIFIER ::= { entityMIBTraps 0 }

entConfigChange NOTIFICATION-TYPE
STATUS current
DESCRIPTION
"An entConfigChange trap is sent when the value of
entLastChangeTime changes. It can be utilized by an NMS to
trigger logical/physical entity table maintenance polls.

An agent must not generate more than one entConfigChange
'trap-event' in a five second period, where a 'trap-event'
is the transmission of a single trap PDU to a list of trap
destinations. If additional configuration changes occur
within the five second 'throttling' period, then these
trap-events should be suppressed by the agent. An NMS should
periodically check the value of entLastChangeTime to detect
any missed entConfigChange trap-events, e.g. due to
throttling or transmission loss."
::= { entityMIBTrapPrefix 1 }

-- conformance information
entityConformance OBJECT IDENTIFIER ::= { entityMIB 3 }

entityCompliances OBJECT IDENTIFIER ::= { entityConformance 1 }
entityGroups OBJECT IDENTIFIER ::= { entityConformance 2 }

-- compliance statements

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entityCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMP entities which implement
the Entity MIB."
MODULE -- this module
MANDATORY-GROUPS { entityPhysicalGroup,
entityLogicalGroup,
entityMappingGroup,
entityGeneralGroup,
entityNotificationsGroup }
::= { entityCompliances 1 }

-- MIB groupings

entityPhysicalGroup OBJECT-GROUP
OBJECTS {
entPhysicalDescr,
entPhysicalVendorType,
entPhysicalContainedIn,
entPhysicalClass,
entPhysicalParentRelPos,
entPhysicalName
}
STATUS current
DESCRIPTION
"The collection of objects which are used to represent
physical system components, for which a single agent
provides management information."
::= { entityGroups 1 }

entityLogicalGroup OBJECT-GROUP
OBJECTS {
entLogicalDescr,
entLogicalType,
entLogicalCommunity,
entLogicalTAddress,
entLogicalTDomain
}
STATUS current
DESCRIPTION
"The collection of objects which are used to represent the
list of logical entities for which a single agent provides
management information."
::= { entityGroups 2 }

entityMappingGroup OBJECT-GROUP
OBJECTS {

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entLPPhysicalIndex,
entAliasMappingIdentifier,
entPhysicalChildIndex
}
STATUS current
DESCRIPTION
"The collection of objects which are used to represent the
associations between multiple logical entities, physical
components, interfaces, and port identifiers for which a
single agent provides management information."
::= { entityGroups 3 }

entityGeneralGroup OBJECT-GROUP
OBJECTS {
entLastChangeTime
}
STATUS current
DESCRIPTION
"The collection of objects which are used to represent
general entity information for which a single agent provides
management information."
::= { entityGroups 4 }

entityNotificationsGroup NOTIFICATION-GROUP
NOTIFICATIONS { entConfigChange }
STATUS current
DESCRIPTION
"The collection of notifications used to indicate Entity MIB
data consistency and general status information."
::= { entityGroups 5 }

END

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5. Usage Examples

The following sections iterate the instance values for two example
networking devices. These examples are kept simple to make them more
understandable. Auxiliary components, such as fans, sensors, empty
slots, and sub-modules are not shown, but might be modeled in real
implementations.

5.1. Router/Bridge

A router containing two slots. Each slot contains a 3 port
router/bridge module. Each port is represented in the ifTable. There
are two logical instances of OSPF running and two logical bridges:

Physical entities -- entPhysicalTable:
1 Field-replaceable physical chassis:
entPhysicalDescr.1 == "Acme Chassis Model 100"
entPhysicalVendorType.1 == acmeProducts.chassisTypes.1
entPhysicalContainedIn.1 == 0
entPhysicalClass.1 == chassis(3)
entPhysicalParentRelPos.1 == 0
entPhysicalName.1 == '100-A'

2 slots within the chassis:
entPhysicalDescr.2 == "Acme Chassis Slot Type AA"
entPhysicalVendorType.2 == acmeProducts.slotTypes.1
entPhysicalContainedIn.2 == 1
entPhysicalClass.2 == container(5)
entPhysicalParentRelPos.2 == 1
entPhysicalName.2 == 'S1'

entPhysicalDescr.3 == "Acme Chassis Slot Type AA"
entPhysicalVendorType.3 == acmeProducts.slotTypes.1
entPhysicalContainedIn.3 == 1
entPhysicalClass.3 == container(5)
entPhysicalParentRelPos.3 == 2
entPhysicalName.3 == 'S2'

2 Field-replaceable modules:
Slot 1 contains a module with 3 ports:
entPhysicalDescr.4 == "Acme Router-100"
entPhysicalVendorType.4 == acmeProducts.moduleTypes.14
entPhysicalContainedIn.4 == 2
entPhysicalClass.4 == module(9)
entPhysicalParentRelPos.4 == 1
entPhysicalName.4 == 'M1'

entPhysicalDescr.5 == "Acme Ethernet-100 Port Rev G"

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entPhysicalVendorType.5 == acmeProducts.portTypes.2
entPhysicalContainedIn.5 == 4
entPhysicalClass.5 == port(10)
entPhysicalParentRelPos.5 == 1
entPhysicalName.5 == 'P1'

entPhysicalDescr.6 == "Acme Ethernet-100 Port Rev G"
entPhysicalVendorType.6 == acmeProducts.portTypes.2
entPhysicalContainedIn.6 == 4
entPhysicalClass.6 == port(10)
entPhysicalParentRelPos.6 == 2
entPhysicalName.6 == 'P2'

entPhysicalDescr.7 == "Acme Router-100 F-Port: Rev B"
entPhysicalVendorType.7 == acmeProducts.portTypes.3
entPhysicalContainedIn.7 == 4
entPhysicalClass.7 == port(10)
entPhysicalParentRelPos.7 == 3
entPhysicalName.7 == 'P3'

Slot 2 contains another 3-port module:
entPhysicalDescr.8 == "Acme Router-100 Comm Module: Rev C"
entPhysicalVendorType.8 == acmeProducts.moduleTypes.15
entPhysicalContainedIn.8 == 3
entPhysicalClass.8 == module(9)
entPhysicalParentRelPos.8 == 1
entPhysicalName.8 == 'M2'

entPhysicalDescr.9 == "Acme Fddi-100 Port Rev CC"
entPhysicalVendorType.9 == acmeProducts.portTypes.5
entPhysicalContainedIn.9 == 8
entPhysicalClass.9 == port(10)
entPhysicalParentRelPos.9 == 1
entPhysicalName.9 == 'FDDI Primary'

entPhysicalDescr.10 == "Acme Ethernet-100 Port Rev G"
entPhysicalVendorType.10 == acmeProducts.portTypes.2
entPhysicalContainedIn.10 == 8
entPhysicalClass.10 == port(10)
entPhysicalParentRelPos.10 == 2
entPhysicalName.10 == 'Ethernet A'

entPhysicalDescr.11 == "Acme Ethernet-100 Port Rev G"
entPhysicalVendorType.11 == acmeProducts.portTypes.2
entPhysicalContainedIn.11 == 8
entPhysicalClass.11 == port(10)
entPhysicalParentRelPos.11 == 3
entPhysicalName.11 == 'Ethernet B'

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Logical entities -- entLogicalTable
2 OSPF instances:
entLogicalDescr.1 == "Acme OSPF v1.1"
entLogicalType.1 == ospf
entLogicalCommunity.1 == "public-ospf1"
entLogicalTAddress.1 == 124.125.126.127:161
entLogicalTDomain.1 == snmpUDPDomain

entLogicalDescr.2 == "Acme OSPF v1.1"
entLogicalType.2 == ospf
entLogicalCommunity.2 == "public-ospf2"
entLogicalTAddress.2 == 124.125.126.127:161
entLogicalTDomain.2 == snmpUDPDomain

2 logical bridges:
entLogicalDescr.3 == "Acme Bridge v2.1.1"
entLogicalType.3 == dod1dBridge
entLogicalCommunity.3 == "public-bridge1"
entLogicalTAddress.3 == 124.125.126.127:161
entLogicalTDomain.3 == snmpUDPDomain

entLogicalDescr.4 == "Acme Bridge v2.1.1"
entLogicalType.4 == dod1dBridge
entLogicalCommunity.4 == "public-bridge2"
entLogicalTAddress.4 == 124.125.126.127:161
entLogicalTDomain.4 == snmpUDPDomain

Logical to Physical Mappings:
1st OSPF instance: uses module 1-port 1
entLPPhysicalIndex.1.5 == 5

2nd OSPF instance: uses module 2-port 1
entLPPhysicalIndex.2.9 == 9

1st bridge group: uses module 1, all ports

[ed. -- Note that these mappings are included in the table since
another logical entity (1st OSPF) utilizes one of the
ports. If this were not the case, then a single mapping
to the module (e.g. entLPPhysicalIndex.3.4) would be
present instead. ]
entLPPhysicalIndex.3.5 == 5
entLPPhysicalIndex.3.6 == 6
entLPPhysicalIndex.3.7 == 7

2nd bridge group: uses module 2, all ports
entLPPhysicalIndex.4.9 == 9
entLPPhysicalIndex.4.10 == 10

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entLPPhysicalIndex.4.11 == 11

Physical to Logical to MIB Alias Mappings -- entAliasMappingTable:
Example 1: ifIndex values are global to all logical entities
entAliasMappingIdentifier.5.0 == ifIndex.1
entAliasMappingIdentifier.6.0 == ifIndex.2
entAliasMappingIdentifier.7.0 == ifIndex.3
entAliasMappingIdentifier.9.0 == ifIndex.4
entAliasMappingIdentifier.10.0 == ifIndex.5
entAliasMappingIdentifier.11.0 == ifIndex.6

Example 2: ifIndex values are not shared by all logical entities
entAliasMappingIdentifier.5.0 == ifIndex.1
entAliasMappingIdentifier.5.3 == ifIndex.101
entAliasMappingIdentifier.6.0 == ifIndex.2
entAliasMappingIdentifier.6.3 == ifIndex.102
entAliasMappingIdentifier.7.0 == ifIndex.3
entAliasMappingIdentifier.7.3 == ifIndex.103
entAliasMappingIdentifier.9.0 == ifIndex.4
entAliasMappingIdentifier.9.3 == ifIndex.204
entAliasMappingIdentifier.10.0 == ifIndex.5
entAliasMappingIdentifier.10.3 == ifIndex.205
entAliasMappingIdentifier.11.0 == ifIndex.6
entAliasMappingIdentifier.11.3 == ifIndex.206

Physical Containment Tree -- entPhysicalContainsTable
chassis has two containers:
entPhysicalChildIndex.1.2 = 2
entPhysicalChildIndex.1.3 = 3

container 1 has a module:
entPhysicalChildIndex.2.4 = 4

container 2 has a module:
entPhysicalChildIndex.3.8 = 8

module 1 has 3 ports:
entPhysicalChildIndex.4.5 = 5
entPhysicalChildIndex.4.6 = 6
entPhysicalChildIndex.4.7 = 7

module 2 has 3 ports:
entPhysicalChildIndex.8.9 = 9
entPhysicalChildIndex.8.10 = 10
entPhysicalChildIndex.1.11 = 11

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5.2. Repeaters

A 3-slot Hub with 2 backplane ethernet segments. Slot three is
empty, and the remaining slots contain ethernet repeater modules.
[ed. -- Note that a replacement for the current Repeater MIB (RFC
1516) is likely to emerge soon, and it will no longer be necessary to
access repeater MIB data in different naming scopes.]

Physical entities -- entPhysicalTable:
1 Field-replaceable physical chassis:
entPhysicalDescr.1 == "Acme Chassis Model 110"
entPhysicalVendorType.1 == acmeProducts.chassisTypes.2
entPhysicalContainedIn.1 == 0
entPhysicalClass.1 == chassis(3)
entPhysicalParentRelPos.1 == 0
entPhysicalName.1 == '110-B'

2 Chassis Ethernet Backplanes:
entPhysicalDescr.2 == "Acme Ethernet Backplane Type A"
entPhysicalVendorType.2 == acmeProducts.backplaneTypes.1
entPhysicalContainedIn.2 == 1
entPhysicalClass.2 == backplane(4)
entPhysicalParentRelPos.2 == 1
entPhysicalName.2 == 'B1'

entPhysicalDescr.3 == "Acme Ethernet Backplane Type A"
entPhysicalVendorType.3 == acmeProducts.backplaneTypes.1
entPhysicalContainedIn.3 == 1
entPhysicalClass.3 == backplane(4)
entPhysicalParentRelPos.3 == 2
entPhysicalName.3 == 'B2'

3 slots within the chassis:
entPhysicalDescr.4 == "Acme Hub Slot Type RB"
entPhysicalVendorType.4 == acmeProducts.slotTypes.5
entPhysicalContainedIn.4 == 1
entPhysicalClass.4 == container(5)
entPhysicalParentRelPos.4 == 1
entPhysicalName.4 == 'Slot 1'

entPhysicalDescr.5 == "Acme Hub Slot Type RB"
entPhysicalVendorType.5 == acmeProducts.slotTypes.5
entPhysicalContainedIn.5 == 1
entPhysicalClass.5 == container(5)
entPhysicalParentRelPos.5 == 2
entPhysicalName.5 == 'Slot 2'

entPhysicalDescr.6 == "Acme Hub Slot Type RB"

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entPhysicalVendorType.6 == acmeProducts.slotTypes.5
entPhysicalContainedIn.6 == 1
entPhysicalClass.6 == container(5)
entPhysicalParentRelPos.6 == 3
entPhysicalName.6 == 'Slot 3'

Slot 1 contains a plug-in module with 4 10-BaseT ports:
entPhysicalDescr.7 == "Acme 10Base-T Module 114 Rev A"
entPhysicalVendorType.7 == acmeProducts.moduleTypes.32
entPhysicalContainedIn.7 == 4
entPhysicalClass.7 == module(9)
entPhysicalParentRelPos.7 == 1
entPhysicalName.7 == 'M1'

entPhysicalDescr.8 == "Acme 10Base-T Port RB Rev A"
entPhysicalVendorType.8 == acmeProducts.portTypes.10
entPhysicalContainedIn.8 == 7
entPhysicalClass.8 == port(10)
entPhysicalParentRelPos.8 == 1
entPhysicalName.8 == 'Ethernet-A'

entPhysicalDescr.9 == "Acme 10Base-T Port RB Rev A"
entPhysicalVendorType.9 == acmeProducts.portTypes.10
entPhysicalContainedIn.9 == 7
entPhysicalClass.9 == port(10)
entPhysicalParentRelPos.9 == 2
entPhysicalName.9 == 'Ethernet-B'

entPhysicalDescr.10 == "Acme 10Base-T Port RB Rev B"
entPhysicalVendorType.10 == acmeProducts.portTypes.10
entPhysicalContainedIn.10 == 7
entPhysicalClass.10 == port(10)
entPhysicalParentRelPos.10 == 3
entPhysicalName.10 == 'Ethernet-C'

entPhysicalDescr.11 == "Acme 10Base-T Port RB Rev B"
entPhysicalVendorType.11 == acmeProducts.portTypes.10
entPhysicalContainedIn.11 == 7
entPhysicalClass.11 == port(10)
entPhysicalParentRelPos.11 == 4
entPhysicalName.11 == 'Ethernet-D'

Slot 2 contains another ethernet module with 2 ports.
entPhysicalDescr.12 == "Acme 10Base-T Module Model 4 Rev A"
entPhysicalVendorType.12 == acmeProducts.moduleTypes.30
entPhysicalContainedIn.12 = 5
entPhysicalClass.12 == module(9)
entPhysicalParentRelPos.12 == 1

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entPhysicalName.12 == 'M2'

entPhysicalDescr.13 == "Acme 802.3 AUI Port Rev A"
entPhysicalVendorType.13 == acmeProducts.portTypes.11
entPhysicalContainedIn.13 == 12
entPhysicalClass.13 == port(10)
entPhysicalParentRelPos.13 == 1
entPhysicalName.13 == 'AUI'

entPhysicalDescr.14 == "Acme 10Base-T Port RD Rev B"
entPhysicalVendorType.14 == acmeProducts.portTypes.14
entPhysicalContainedIn.14 == 12
entPhysicalClass.14 == port(10)
entPhysicalParentRelPos.14 == 2
entPhysicalName.14 == 'E2'

Logical entities -- entLogicalTable
Repeater 1--comprised of any ports attached to backplane 1
entLogicalDescr.1 == "Acme repeater v3.1"
entLogicalType.1 == snmpDot3RptrMgt
entLogicalCommunity.1 "public-repeater1"
entLogicalTAddress.1 == 124.125.126.127:161
entLogicalTDomain.1 == snmpUDPDomain

Repeater 2--comprised of any ports attached to backplane 2:
entLogicalDescr.2 == "Acme repeater v3.1"
entLogicalType.2 == snmpDot3RptrMgt
entLogicalCommunity.2 == "public-repeater2"
entLogicalTAddress.2 == 124.125.126.127:161
entLogicalTDomain.2 == snmpUDPDomain

Logical to Physical Mappings -- entLPMappingTable:

repeater1 uses backplane 1, slot 1-ports 1 & 2, slot 2-port 1
[ed. -- Note that a mapping to the module is not included,
since in this example represents a port-switchable hub.
Even though all ports on the module could belong to the
same repeater as a matter of configuration, the LP port
mappings should not be replaced dynamically with a single
mapping for the module (e.g. entLPPhysicalIndex.1.7).
If all ports on the module shared a single backplane connection,
then a single mapping for the module would be more appropriate. ]

entLPPhysicalIndex.1.2 == 2
entLPPhysicalIndex.1.8 == 8
entLPPhysicalIndex.1.9 == 9
entLPPhysicalIndex.1.13 == 13

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repeater2 uses backplane 2, slot 1-ports 3 & 4, slot 2-port 2
entLPPhysicalIndex.2.3 == 3
entLPPhysicalIndex.2.10 == 10
entLPPhysicalIndex.2.11 == 11
entLPPhysicalIndex.2.14 == 14

Physical to Logical to MIB Alias Mappings -- entAliasMappingTable:
Repeater Port Identifier values are shared by both repeaters:
entAliasMappingIdentifier.8.0 == rptrPortGroupIndex.1.1
entAliasMappingIdentifier.9.0 == rptrPortGroupIndex.1.2
entAliasMappingIdentifier.10.0 == rptrPortGroupIndex.1.3
entAliasMappingIdentifier.11.0 == rptrPortGroupIndex.1.4
entAliasMappingIdentifier.13.0 == rptrPortGroupIndex.2.1
entAliasMappingIdentifier.14.0 == rptrPortGroupIndex.2.2

Physical Containment Tree -- entPhysicalContainsTable
chassis has two backplanes and three containers:
entPhysicalChildIndex.1.2 = 2
entPhysicalChildIndex.1.3 = 3
entPhysicalChildIndex.1.4 = 4
entPhysicalChildIndex.1.5 = 5
entPhysicalChildIndex.1.6 = 6

container 1 has a module:
entPhysicalChildIndex.4.7 = 7

container 2 has a module
entPhysicalChildIndex.5.12 = 12
[ed. - in this example, container 3 is empty.]

module 1 has 4 ports:
entPhysicalChildIndex.7.8 = 8
entPhysicalChildIndex.7.9 = 9
entPhysicalChildIndex.7.10 = 10
entPhysicalChildIndex.7.11 = 11

module 2 has 2 ports:
entPhysicalChildIndex.12.13 = 13
entPhysicalChildIndex.12.14 = 14

6. Acknowledgements

This document was produced by the IETF Entity MIB Working Group.

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RFC 2037 Entity MIB using SMIv2 October 1996

7. References

[1] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Structure of Management Information for version 2
of the Simple Network Management Protocol (SNMPv2)", RFC 1902,
January 1996.

[2] McCloghrie, K., and M. Rose, Editors, "Management Information Base
for Network Management of TCP/IP-based internets: MIB-II", STD 17,
RFC 1213, Hughes LAN Systems, Performance Systems International,
March 1991.

[3] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Textual Conventions for version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1903, January 1996.

[4] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Protocol Operations for version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1905, January 1996.

[5] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Conformance Statements for version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1904, January 1996.

[6] Case, J., M. Fedor, M. Schoffstall, J. Davin, "Simple Network
Management Protocol", RFC 1157, SNMP Research, Performance Systems
International, MIT Laboratory for Computer Science, May 1990.

[7] McCloghrie, K., and Kastenholtz, F., "Interfaces Group Evolution",
RFC 1573, Hughes LAN Systems, FTP Software, January 1994.

[8] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Transport Mappings for version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1906, January 1996.

[9] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901,
January 1996.

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RFC 2037 Entity MIB using SMIv2 October 1996

8. Security Considerations

In order to implement this MIB, an agent must make certain management
information available about various logical and physical entities
within a managed system, which may be considered sensitive in some
network environments.

Therefore, a network administrator may wish to employ instance-level
access control, and configure the Entity MIB access (i.e., community
strings in SNMPv1 and SNMPv2C), such that certain instances within
this MIB (e.g., entLogicalCommunity, or entire entLogicalEntries,
entPhysicalEntries, and associated mapping table entries), are
excluded from particular MIB views.

9. Authors' Addresses

Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134

Phone: 408-526-5260
EMail: [email protected]

Andy Bierman
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134

Phone: 408-527-3711
EMail: [email protected]

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