Network Working Group G. Renker

Network Working Group G. Renker
Request for Comments: 5097 G. Fairhurst
Category: Standards Track University of Aberdeen
January 2008

MIB for the UDP-Lite Protocol

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.

Abstract

This document specifies a Management Information Base (MIB) module
for the Lightweight User Datagram Protocol (UDP-Lite). It defines a
set of new MIB objects to characterise the behaviour and performance
of transport layer endpoints deploying UDP-Lite. UDP-Lite resembles
UDP, but differs from the semantics of UDP by the addition of a
single option. This adds the capability for variable-length data
checksum coverage, which can benefit a class of applications that
prefer delivery of (partially) corrupted datagram payload data in
preference to discarding the datagram.

Table of Contents

1. Introduction ....................................................2
1.1. Relationship to the UDP-MIB ................................2
1.2. Relationship to HOST-RESOURCES-MIB and SYSAPPL-MIB .........4
1.3. Interpretation of the MIB Variables ........................5
1.4. Conventions ................................................8
2. The Internet-Standard Management Framework ......................8
3. Definitions .....................................................8
4. Security Considerations ........................................19
5. IANA Considerations ............................................20
6. Acknowledgments ................................................20
7. References .....................................................20
7.1. Normative References ......................................20
7.2. Informative References ....................................21

Renker & Fairhurst Standards Track [Page 1]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

1. Introduction

The Lightweight User Datagram Protocol (UDP-Lite) [RFC3828] (also
known as UDPLite) is an IETF standards-track transport protocol. The
operation of UDP-Lite is similar to the User Datagram Protocol (UDP)
[RFC768], but can also serve applications in error-prone network
environments that prefer to have partially damaged payloads delivered
rather than discarded. This is achieved by changing the semantics of
the UDP Length field to that of a Checksum Coverage field. If this
feature is not used, UDP-Lite is semantically identical to UDP.

The interface of UDP-Lite differs from that of UDP by the addition of
a single option, which communicates a length value. At the sender
this specifies the intended datagram checksum coverage; at the
receiver it signifies a minimum coverage threshold for incoming
datagrams. This length value may also be modified during the
lifetime of a connection. UDP-Lite does not provide mechanisms to
negotiate the checksum coverage between the sender and receiver.
Where required, this needs to be communicated by another protocol.
The Datagram Congestion Control Protocol (DCCP) [RFC4340] for
instance includes a capability to negotiate checksum coverage values.

This document defines a set of runtime statistics (variables) that
facilitate network management/monitoring as well as unified
comparisons between different protocol implementations and operating
environments. To provide a common interface for users and
implementors of UDP-Lite modules, the definitions of these runtime
statistics are provided as a MIB module using the SMIv2 format
[RFC2578].

1.1. Relationship to the UDP-MIB

The similarities between UDP and UDP-Lite suggest that the MIB module
for UDP-Lite should resemble that of UDP [RFC4113], with extensions
corresponding to the additional capabilities of UDP-Lite. The UDP-
Lite MIB module is placed beneath the mib-2 subtree, adhering to the
familiar structure of the UDP-MIB module to ease integration.

In particular, these well-known basic counters are supported:

o InDatagrams

o NoPorts

o InErrors

o OutDatagrams

Renker & Fairhurst Standards Track [Page 2]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

The following read-only variables have been added to the basic
structure used in the UDP-MIB module:

InPartialCov: The number of received datagrams, with a valid
format and checksum, whose checksum coverage is strictly less than
the datagram length.

InBadChecksum: The number of received datagrams with an invalid
checksum (i.e., where the receiver-recalculated UDP-Lite checksum
does not match that in the Checksum field). Unlike NoPorts, this
error type also counts as InErrors.

OutPartialCov: The number of sent datagrams with a valid format
and checksum whose checksum coverage is strictly less than the
datagram length.

All non-error counters used in this document are 64-bit counters.
This is a departure from UDP, which traditionally used 32-bit
counters and mandates 64-bit counters only on fast networks
[RFC4113]. This choice is justified by the fact that UDP-Lite is a
more recent protocol, and that network speeds continue to grow.

Another difference from the UDP MIB module is that the UDP-Lite MIB
module does not support an IPv4-only listener table. This feature
was present only for compatibility reasons and is superseded by the
more informative endpoint table. Two columnar objects have been
added to this table:

udpliteEndpointMinCoverage: The minimum acceptable receiver
checksum coverage length [RFC3828]. This value may be manipulated
by the application attached to the receiving endpoint.

udpliteEndpointViolCoverage: This object is optional and counts
the number of valid datagrams with a checksum coverage value less
than the corresponding value of udpliteEndpointMinCoverage.
Although being otherwise valid, such datagrams are discarded
rather than passed to the application. This object thus serves to
separate cases of violated coverage from other InErrors.

The second entry is not required to manage the transport protocol and
hence is not mandatory. It may be implemented to assist in debugging
application design and configuration.

The UDP-Lite MIB module also provides a discontinuity object to help
determine whether one or more of its counters experienced a
discontinuity event. This is an event, other than re-initialising
the management system, that invalidates the management entity's
understanding of the counter values.

Renker & Fairhurst Standards Track [Page 3]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

For example, if UDP-Lite is implemented as a loadable operating
system module, a module load or unload would produce a discontinuity.
By querying the value of udpliteStatsDiscontinuityTime, a management
entity can determine whether or not a discontinuity event has
occurred.

1.2. Relationship to HOST-RESOURCES-MIB and SYSAPPL-MIB

The UDP-Lite endpoint table contains one columnar object,
udpliteEndpointProcess, reporting a unique value that identifies a
distinct piece of software associated with this endpoint. (When more
than one piece of software is associated with this endpoint, a
representative is chosen, so that consecutive queries consistently
refer to the same identifier. The reported value is then consistent,
as long as the representative piece of software is running and still
associated with the endpoint.)

The value of udpliteEndpointProcess is reported as an Unsigned32, and
it shares with the hrSWRunIndex of the HOST-RESOURCES-MIB [RFC2790]
and the sysApplElmtRunIndex of the SYSAPPL-MIB [RFC2287] the
requirement that, wherever possible, this should be the native and
unique identification number employed by the system.

If the SYSAPPL-MIB module is available, the value of
udpliteEndpointProcess should correspond to the appropriate value of
sysApplElmtRunIndex. If not available, an alternative should be used
(e.g., the hrSWRunIndex of the HOST-RESOURCES-MIB module).

Renker & Fairhurst Standards Track [Page 4]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

1.3. Interpretation of the MIB Variables

Figure 1 shows an informal survey of the packet processing path, with
reference to counter names in parentheses.

Received UDP-Lite Datagrams
|
| +- Full Coverage ---------------------+-> Deliver
| | |
+- Valid Header--+ +- >= Rec. Coverage --+
| (InDatagrams) | |
| +- Partial -----+
| (InPartialCov) |
| +- < Rec. Coverage --+
| (EndpointViolCoverage) |
| |
| |
+- Header Error ---+ |
| | |
+- Checksum Error -+-----------------------------------+-> Discard
| (InBadChecksum) (InErrors)
|
+- Port Error -------------------------------------------> Discard
(NoPorts)

Figure 1: UDP-Lite Input Processing Path

A platform-independent test of the UDP-Lite implementations in two
connected end hosts may be performed as follows.

On the sending side, OutDatagrams and OutPartialCov are observed.
The ratio OutPartialCov/OutDatagrams describes the fraction (between
0 and 1) of datagrams using partial checksum coverage.

On the receiving side, InDatagrams, InPartialCov, and InErrors are
monitored. If datagrams are received from the given sender, InErrors
is close to zero, and InPartialCov is zero, no partial coverage is
employed. If no datagrams are received and InErrors increases
proportionally with the sending rate, a configuration error is likely
(a wrong value of receiver minimum checksum coverage).

The InBadChecksum counter reflects errors that may persist following
end-host processing, router processing, or link processing (this
includes illegal coverage values as defined in [RFC3828], since
checksum and checksum coverage are mutually interdependent). In
particular, InBadChecksum can serve as an indicator of the residual

Renker & Fairhurst Standards Track [Page 5]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

link bit error rate: on links with higher bit error rates, a lower
value of the checksum coverage may help to reduce the values of both
InErrors and InBadChecksum. By observing these values and adapting
the configuration, a setting may then be found that is more adapted
to the specific type of link, and the type of payload. In
particular, a reduction in the number of discarded datagrams
(InErrors), may indicate an improved performance.

The above statistics are elementary and can be used to derive the
following information:

o The total number of incoming datagrams is InDatagrams + InErrors +
NoPorts.

o The number of InErrors that were discarded due to problems other
than a bad checksum is InErrors - InBadChecksum.

o The number of InDatagrams that have full coverage is InDatagrams -
InPartialCov.

o The number of OutDatagrams that have full coverage is OutDatagrams
- OutPartialCov.

Renker & Fairhurst Standards Track [Page 6]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

The following Case diagram [CASE] summarises the relationships
between the counters on the input processing path.

Transport Layer Interface
-------------------------------------------------------------
/\
||
----------------------------- InDatagrams
|| ^
|| |
|| |
||----------------------> InPartialCov
|| |
|| |
|| v
|| EndpointViolCoverage
|| |
NoPorts <--------|| |
|| |
||------> InBadChecksum ------>|
|| |
|| |
|| v
||------------------------> InErrors
||
||
-------------------------------------------------------------
Network Layer Interface

Figure 2: Counters for Received UDP-Lite Datagrams

A configuration error may occur when a sender chooses a coverage
value for the datagrams that it sends that is less than the minimum
coverage configured by the intended recipient. The minimum coverage
is set on a per-session basis by the application associated with the
listening endpoint, and its current value is recorded in the
udpliteEndpointTable. Reception of valid datagrams with a checksum
coverage value less than this threshold results in dropping the
datagram [RFC3828] and incrementing InErrors. To improve debugging
of such (misconfigured) cases, an implementer may choose to support
the optional udpliteEndpointViolCoverage entry in the endpoint table
(Section 1.1) that specifically counts datagrams falling in this
category. Without this feature, failure due to misconfiguration can
not be distinguished from datagram processing failure.

Renker & Fairhurst Standards Track [Page 7]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

1.4. Conventions

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 BCP 14 [RFC2119].

2. The Internet-Standard Management Framework

For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [RFC3410].

Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
[RFC2580].

3. Definitions

UDPLITE-MIB DEFINITIONS ::= BEGIN

IMPORTS
MODULE-IDENTITY,
OBJECT-TYPE,
mib-2, Unsigned32,
Counter32, Counter64 FROM SNMPv2-SMI -- [RFC2578]

TimeStamp FROM SNMPv2-TC -- [RFC2579]

MODULE-COMPLIANCE,
OBJECT-GROUP FROM SNMPv2-CONF -- [RFC2580]

InetAddress,
InetAddressType,
InetPortNumber FROM INET-ADDRESS-MIB; -- [RFC4001]

udpliteMIB MODULE-IDENTITY
LAST-UPDATED "200712180000Z" -- 18 December 2007
ORGANIZATION "IETF TSV Working Group (TSVWG)"
CONTACT-INFO
"IETF TSV Working Group
http://www.ietf.org/html.charters/tsvwg-charter.html
Mailing List: [email protected]

Renker & Fairhurst Standards Track [Page 8]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

Gerrit Renker, Godred Fairhurst
Electronics Research Group
School of Engineering, University of Aberdeen
Fraser Noble Building, Aberdeen AB24 3UE, UK"
DESCRIPTION
"The MIB module for managing UDP-Lite implementations.
Copyright (C) The IETF Trust (2008). This version of
this MIB module is part of RFC 5097; see the RFC
itself for full legal notices."

REVISION "200712180000Z" -- 18 December 2007
DESCRIPTION
"Initial SMIv2 revision, based on the format of the UDP
MIB module (RFC 4113) and published as RFC 5097."
::= { mib-2 170 }

udplite OBJECT IDENTIFIER ::= { udpliteMIB 1 }

udpliteInDatagrams OBJECT-TYPE -- as in UDP-MIB
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of UDP-Lite datagrams that were
delivered to UDP-Lite users.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udplite 1 }

udpliteInPartialCov OBJECT-TYPE -- new in UDP-Lite
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of UDP-Lite datagrams that were
delivered to UDP-Lite users (applications) and whose
checksum coverage was strictly less than the datagram
length.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udplite 2 }

Renker & Fairhurst Standards Track [Page 9]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

udpliteNoPorts OBJECT-TYPE -- as in UDP-MIB
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of received UDP-Lite datagrams for
which there was no listener at the destination port.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udplite 3 }

udpliteInErrors OBJECT-TYPE -- as in UDP-MIB
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of received UDP-Lite datagrams that could not
be delivered for reasons other than the lack of an
application at the destination port.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udplite 4 }

udpliteInBadChecksum OBJECT-TYPE -- new in UDP-Lite
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of received UDP-Lite datagrams whose checksum
could not be validated. This includes illegal checksum
coverage values, as their use would lead to incorrect
checksums.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
REFERENCE "RFC 3828, section 3.1"
::= { udplite 5 }

udpliteOutDatagrams OBJECT-TYPE -- as in UDP-MIB
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION

Renker & Fairhurst Standards Track [Page 10]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

"The total number of UDP-Lite datagrams sent from this
entity.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udplite 6 }

udpliteOutPartialCov OBJECT-TYPE -- new in UDP-Lite
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of udpliteOutDatagrams whose
checksum coverage was strictly less than the
datagram length.
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udplite 7 }

udpliteEndpointTable OBJECT-TYPE
SYNTAX SEQUENCE OF UdpLiteEndpointEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A table containing information about this entity's
UDP-Lite endpoints on which a local application is
currently accepting or sending datagrams.

The address type in this table represents the address
type used for the communication, irrespective of the
higher-layer abstraction. For example, an application
using IPv6 'sockets' to communicate via IPv4 between
::ffff:10.0.0.1 and ::ffff:10.0.0.2 would use
InetAddressType ipv4(1).

Like the udpTable in RFC 4113, this table also allows
the representation of an application that completely
specifies both local and remote addresses and ports. A
listening application is represented in three possible
ways:

1) An application that is willing to accept both IPv4
and IPv6 datagrams is represented by a
udpliteEndpointLocalAddressType of unknown(0) and a
udpliteEndpointLocalAddress of ''h (a zero-length

Renker & Fairhurst Standards Track [Page 11]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

octet-string).

2) An application that is willing to accept only IPv4
or only IPv6 datagrams is represented by a
udpliteEndpointLocalAddressType of the appropriate
address type and a udpliteEndpointLocalAddress of
'0.0.0.0' or '::' respectively.

3) An application that is listening for datagrams only
for a specific IP address but from any remote
system is represented by a
udpliteEndpointLocalAddressType of the appropriate
address type, with udpliteEndpointLocalAddress
specifying the local address.

In all cases where the remote address is a wildcard,
the udpliteEndpointRemoteAddressType is unknown(0),
the udpliteEndpointRemoteAddress is ''h (a zero-length
octet-string), and the udpliteEndpointRemotePort is 0.

If the operating system is demultiplexing UDP-Lite
packets by remote address/port, or if the application
has 'connected' the socket specifying a default remote
address/port, the udpliteEndpointRemote* values should
be used to reflect this."
::= { udplite 8 }

udpliteEndpointEntry OBJECT-TYPE
SYNTAX UdpLiteEndpointEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information about a particular current UDP-Lite endpoint.
Implementers need to pay attention to the sizes of
udpliteEndpointLocalAddress/RemoteAddress, as Object
Identifiers (OIDs) of column instances in this table must
have no more than 128 sub-identifiers in order to remain
accessible with SNMPv1, SNMPv2c, and SNMPv3."
INDEX { udpliteEndpointLocalAddressType,
udpliteEndpointLocalAddress,
udpliteEndpointLocalPort,
udpliteEndpointRemoteAddressType,
udpliteEndpointRemoteAddress,
udpliteEndpointRemotePort,
udpliteEndpointInstance }
::= { udpliteEndpointTable 1 }

UdpLiteEndpointEntry ::= SEQUENCE {

Renker & Fairhurst Standards Track [Page 12]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

udpliteEndpointLocalAddressType InetAddressType,
udpliteEndpointLocalAddress InetAddress,
udpliteEndpointLocalPort InetPortNumber,
udpliteEndpointRemoteAddressType InetAddressType,
udpliteEndpointRemoteAddress InetAddress,
udpliteEndpointRemotePort InetPortNumber,
udpliteEndpointInstance Unsigned32,
udpliteEndpointProcess Unsigned32,
udpliteEndpointMinCoverage Unsigned32,
udpliteEndpointViolCoverage Counter32
}

udpliteEndpointLocalAddressType OBJECT-TYPE
SYNTAX InetAddressType
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The address type of udpliteEndpointLocalAddress. Only
IPv4, IPv4z, IPv6, and IPv6z addresses are expected, or
unknown(0) if datagrams for all local IP addresses are
accepted."
::= { udpliteEndpointEntry 1 }

udpliteEndpointLocalAddress OBJECT-TYPE
SYNTAX InetAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The local IP address for this UDP-Lite endpoint.

The value of this object can be represented in three
possible ways, depending on the characteristics of the
listening application:

1. For an application that is willing to accept both
IPv4 and IPv6 datagrams, the value of this object
must be ''h (a zero-length octet-string), with
the value of the corresponding instance of the
EndpointLocalAddressType object being unknown(0).

2. For an application that is willing to accept only
IPv4 or only IPv6 datagrams, the value of this
object must be '0.0.0.0' or '::', respectively,
while the corresponding instance of the
EndpointLocalAddressType object represents the
appropriate address type.

3. For an application that is listening for data

Renker & Fairhurst Standards Track [Page 13]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

destined only to a specific IP address, the value
of this object is the specific IP address for
which this node is receiving packets, with the
corresponding instance of the
EndpointLocalAddressType object representing the
appropriate address type.

As this object is used in the index for the
udpliteEndpointTable, implementors should be careful
not to create entries that would result in OIDs with
more than 128 sub-identifiers; this is because of SNMP
and SMI limitations."
::= { udpliteEndpointEntry 2 }

udpliteEndpointLocalPort OBJECT-TYPE
SYNTAX InetPortNumber
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The local port number for this UDP-Lite endpoint."
::= { udpliteEndpointEntry 3 }

udpliteEndpointRemoteAddressType OBJECT-TYPE
SYNTAX InetAddressType
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The address type of udpliteEndpointRemoteAddress. Only
IPv4, IPv4z, IPv6, and IPv6z addresses are expected, or
unknown(0) if datagrams for all remote IP addresses are
accepted. Also, note that some combinations of
udpliteEndpointLocalAdressType and
udpliteEndpointRemoteAddressType are not supported. In
particular, if the value of this object is not
unknown(0), it is expected to always refer to the
same IP version as udpliteEndpointLocalAddressType."
::= { udpliteEndpointEntry 4 }

udpliteEndpointRemoteAddress OBJECT-TYPE
SYNTAX InetAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The remote IP address for this UDP-Lite endpoint. If
datagrams from any remote system are to be accepted,
this value is ''h (a zero-length octet-string).
Otherwise, it has the type described by
udpliteEndpointRemoteAddressType and is the address of

Renker & Fairhurst Standards Track [Page 14]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

the remote system from which datagrams are to be
accepted (or to which all datagrams will be sent).

As this object is used in the index for the
udpliteEndpointTable, implementors should be careful
not to create entries that would result in OIDs with
more than 128 sub-identifiers; this is because of SNMP
and SMI limitations."
::= { udpliteEndpointEntry 5 }

udpliteEndpointRemotePort OBJECT-TYPE
SYNTAX InetPortNumber
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The remote port number for this UDP-Lite endpoint. If
datagrams from any remote system are to be accepted,
this value is zero."
::= { udpliteEndpointEntry 6 }

udpliteEndpointInstance OBJECT-TYPE
SYNTAX Unsigned32 (1..'ffffffff'h)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The instance of this tuple. This object is used to
distinguish among multiple processes 'connected' to
the same UDP-Lite endpoint. For example, on a system
implementing the BSD sockets interface, this would be
used to support the SO_REUSEADDR and SO_REUSEPORT
socket options."
::= { udpliteEndpointEntry 7 }

udpliteEndpointProcess OBJECT-TYPE
SYNTAX Unsigned32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A unique value corresponding to a piece of software
running on this endpoint.

If this endpoint is associated with more than one piece
of software, the agent should choose one of these. As
long as the representative piece of software
is running and still associated with the endpoint,
subsequent reads will consistently return the same
value. The implementation may use any algorithm
satisfying these constraints (e.g., choosing the entity

Renker & Fairhurst Standards Track [Page 15]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

with the oldest start time).

This identifier is platform-specific. Wherever possible,
it should use the system's native, unique identification
number as the value.

If the SYSAPPL-MIB module is available, the value should
be the same as sysApplElmtRunIndex. If not available, an
alternative should be used (e.g., the hrSWRunIndex of the
HOST-RESOURCES-MIB module).

If it is not possible to uniquely identify the pieces of
software associated with this endpoint, then the value
zero should be used. (Note that zero is otherwise a
valid value for sysApplElmtRunIndex.)"
::= { udpliteEndpointEntry 8 }

udpliteEndpointMinCoverage OBJECT-TYPE -- new in UDP-Lite
SYNTAX Unsigned32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The minimum checksum coverage expected by this endpoint.
A value of 0 indicates that only fully covered datagrams
are accepted."
REFERENCE "RFC 3828, section 3.1"
::= { udpliteEndpointEntry 9 }

udpliteEndpointViolCoverage OBJECT-TYPE -- new / optional in UDP-Lite
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of datagrams received by this endpoint whose
checksum coverage violated the minimum coverage threshold
set for this connection (i.e., all valid datagrams whose
checksum coverage was strictly smaller than the minimum,
as defined in RFC 3828).
Discontinuities in the value of this counter can occur
at re-initialisation of the management system, and at
other times as indicated by the value of
udpliteStatsDiscontinuityTime."
::= { udpliteEndpointEntry 10 }

Renker & Fairhurst Standards Track [Page 16]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

udpliteStatsDiscontinuityTime OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the most recent occasion at
which one or more of the UDP-Lite counters suffered a
discontinuity.
A value of zero indicates no such discontinuity has
occurred since the last re-initialisation of the local
management subsystem."
::= { udplite 9 }

-- Conformance Information

udpliteMIBConformance OBJECT IDENTIFIER ::= { udpliteMIB 2 }

udpliteMIBCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for systems that implement
UDP-Lite.

There are a number of INDEX objects that cannot be
represented in the form of OBJECT clauses in SMIv2,
but for which we have the following compliance
requirements, expressed in OBJECT clause form in this
description clause:

-- OBJECT udpliteEndpointLocalAddressType
-- SYNTAX InetAddressType { unknown(0), ipv4(1),
-- ipv6(2), ipv4z(3),
-- ipv6z(4) }
-- DESCRIPTION
-- Support for dns(16) is not required.
-- OBJECT udpliteEndpointLocalAddress
-- SYNTAX InetAddress (SIZE(0|4|8|16|20))
-- DESCRIPTION
-- Support is only required for zero-length
-- octet-strings, and for scoped and unscoped
-- IPv4 and IPv6 addresses.
-- OBJECT udpliteEndpointRemoteAddressType
-- SYNTAX InetAddressType { unknown(0), ipv4(1),
-- ipv6(2), ipv4z(3),
-- ipv6z(4) }
-- DESCRIPTION
-- Support for dns(16) is not required.
-- OBJECT udpliteEndpointRemoteAddress

Renker & Fairhurst Standards Track [Page 17]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

-- SYNTAX InetAddress (SIZE(0|4|8|16|20))
-- DESCRIPTION
-- Support is only required for zero-length
-- octet-strings, and for scoped and unscoped
-- IPv4 and IPv6 addresses.
"
MODULE -- this module
MANDATORY-GROUPS { udpliteBaseGroup,
udplitePartialCsumGroup,
udpliteEndpointGroup }
GROUP udpliteAppGroup
DESCRIPTION
"This group is optional and provides supplementary
information about the effectiveness of using minimum
checksum coverage thresholds on endpoints."
::= { udpliteMIBConformance 1 }

udpliteMIBGroups OBJECT IDENTIFIER ::= { udpliteMIBConformance 2 }

udpliteBaseGroup OBJECT-GROUP -- as in UDP
OBJECTS { udpliteInDatagrams, udpliteNoPorts, udpliteInErrors,
udpliteOutDatagrams, udpliteStatsDiscontinuityTime }
STATUS current
DESCRIPTION
"The group of objects providing for counters of
basic UDP-like statistics."
::= { udpliteMIBGroups 1 }

udplitePartialCsumGroup OBJECT-GROUP -- specific to UDP-Lite
OBJECTS { udpliteInPartialCov,
udpliteInBadChecksum,
udpliteOutPartialCov }
STATUS current
DESCRIPTION
"The group of objects providing for counters of
transport layer statistics exclusive to UDP-Lite."
::= { udpliteMIBGroups 2 }

udpliteEndpointGroup OBJECT-GROUP
OBJECTS { udpliteEndpointProcess, udpliteEndpointMinCoverage }
STATUS current
DESCRIPTION
"The group of objects providing for the IP version
independent management of UDP-Lite 'endpoints'."
::= { udpliteMIBGroups 3 }

Renker & Fairhurst Standards Track [Page 18]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

udpliteAppGroup OBJECT-GROUP
OBJECTS { udpliteEndpointViolCoverage }
STATUS current
DESCRIPTION
"The group of objects that provide application-level
information for the configuration management of
UDP-Lite 'endpoints'."
::= { udpliteMIBGroups 4 }

END

4. Security Considerations

There are no management objects defined in this MIB module that have
a MAX-ACCESS clause of read-write and/or read-create. So, if this
MIB module is implemented correctly, then there is no risk that an
intruder can alter or create any management objects of this MIB
module via direct SNMP SET operations.

Some of the readable objects in this MIB module (i.e., objects with a
MAX-ACCESS other than not-accessible) may be considered sensitive or
vulnerable in some network environments. It is thus important to
control even GET and/or NOTIFY access to these objects and possibly
to even encrypt the values of these objects when sending them over
the network via SNMP. These are the tables and objects and their
sensitivity/vulnerability:

The indices of the udpliteEndpointTable contain information about the
listeners on an entity. In particular, the udpliteEndpointLocalPort
index objects can be used to identify ports that are open on the
machine and which attacks are likely to succeed, without the attacker
having to run a port scanner. The table also identifies the
currently listening UDP-Lite ports.

The udpliteEndpointMinCoverage provides information about the
requirements of the transport service associated with a specific
UDP-Lite port. This provides additional detail concerning the type
of application associated with the port at the receiver.

Since UDP-Lite permits the delivery of (partially) corrupted data to
an end host, the counters defined in this MIB module may be used to
infer information about the characteristics of the end-to-end path
over which the datagrams are communicated. This information could be
used to infer the type of application associated with the port at the
receiver.

SNMP versions prior to SNMPv3 did not include adequate security.
Even if the network itself is secure (for example by using IPsec),

Renker & Fairhurst Standards Track [Page 19]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

even then, there is no control as to who on the secure network is
allowed to access and GET/SET (read/change/create/delete) the objects
in this MIB module.

It is RECOMMENDED that implementers consider the security features as
provided by the SNMPv3 framework (see RFC 3410 [RFC3410], section 8),
including full support for the SNMPv3 cryptographic mechanisms (for
authentication and privacy).

Further, deployment of SNMP versions prior to SNMPv3 is NOT
RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to
enable cryptographic security. It is then a customer/operator
responsibility to ensure that the SNMP entity giving access to an
instance of this MIB module is properly configured to give access to
the objects only to those principals (users) that have legitimate
rights to indeed GET or SET (change/create/delete) them.

5. IANA Considerations

The MIB module in this document uses the following IANA-assigned
OBJECT IDENTIFIER values recorded in the SMI Numbers registry:

+------------+-------------------------+
| Descriptor | OBJECT IDENTIFIER value |
+------------+-------------------------+
| udpliteMIB | { mib-2 170 } |
+------------+-------------------------+

6. Acknowledgments

The design of the MIB module presented in this document owes much to
the format of the module presented in [RFC4113].

7. References

7.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2578] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M., and S. Waldbusser, "Structure of Management
Information Version 2 (SMIv2)", STD 58, RFC 2578, April
1999.

[RFC2579] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M., and S. Waldbusser, "Textual Conventions for
SMIv2", STD 58, RFC 2579, April 1999.

Renker & Fairhurst Standards Track [Page 20]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

[RFC2580] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M., and S. Waldbusser, "Conformance Statements for
SMIv2", STD 58, RFC 2580, April 1999.

[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., and
G. Fairhurst, "The Lightweight User Datagram Protocol
(UDP-Lite)", RFC 3828, July 2004.

[RFC4001] Daniele, M., Haberman, B., Routhier, S., and J.
Schoenwaelder, "Textual Conventions for Internet Network
Addresses", RFC 4001, February 2005.

7.2. Informative References

[CASE] Case, J. and C. Partridge, "Case Diagrams: A First Step to
Diagrammed Management Information Bases", ACM Computer
Communications Review, 19(1):13-16, January 1989.

[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.

[RFC2287] Krupczak, C. and J. Saperia, "Definitions of System-Level
Managed Objects for Applications", RFC 2287, February
1998.

[RFC2790] Waldbusser, S. and P. Grillo, "Host Resources MIB", RFC
2790, March 2000.

[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002.

[RFC4113] Fenner, B. and J. Flick, "Management Information Base for
the User Datagram Protocol (UDP)", RFC 4113, June 2005.

[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
Congestion Control Protocol (DCCP)", RFC 4340, March 2006.

Renker & Fairhurst Standards Track [Page 21]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

Authors' Addresses

Gerrit Renker
University of Aberdeen
School of Engineering
Fraser Noble Building
Aberdeen AB24 3UE
Scotland

EMail: [email protected]
URI: http://www.erg.abdn.ac.uk

Godred Fairhurst
University of Aberdeen
School of Engineering
Fraser Noble Building
Aberdeen AB24 3UE
Scotland

EMail: [email protected]
URI: http://www.erg.abdn.ac.uk

Renker & Fairhurst Standards Track [Page 22]

RFC 5097 MIB for the UDP-Lite Protocol January 2008

Full Copyright Statement

Copyright (C) The IETF Trust (2008).

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, THE IETF TRUST 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
[email protected].

Renker & Fairhurst Standards Track [Page 23]