[Docs] [txt|pdf] [draft-ietf-tsvwg-...] [Diff1] [Diff2]

PROPOSED STANDARD

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








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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




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   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.



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   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).
























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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





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   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.





























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   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.







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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: tsvwg@ietf.org




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               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 }






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   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



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              "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



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                  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 {



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           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



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                  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



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               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



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               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 }








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   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



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               -- 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 }






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   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),



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   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.



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   [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.














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Authors' Addresses

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

   EMail: gerrit@erg.abdn.ac.uk
   URI:   http://www.erg.abdn.ac.uk


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

   EMail: gorry@erg.abdn.ac.uk
   URI:   http://www.erg.abdn.ac.uk





























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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.

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   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
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   Copies of IPR disclosures made to the IETF Secretariat and any
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   The IETF invites any interested party to bring to its attention any
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   ietf-ipr@ietf.org.












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