rfc2667.txt

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Network Working Group                                          D. Thaler
Request for Comments: 2667                                     Microsoft
Category: Standards Track                                    August 1999


                             IP Tunnel MIB

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

1.  Abstract

   This memo defines a Management Information Base (MIB) for use with
   network management protocols in the Internet community.  In
   particular, it describes managed objects used for managing tunnels of
   any type over IPv4 networks.  Extension MIBs may be designed for
   managing protocol-specific objects. Likewise, extension MIBs may be
   designed for managing security-specific objects.  This MIB does not
   support tunnels over non-IPv4 networks (including IPv6 networks).
   Management of such tunnels may be supported by other MIBs.

Table of Contents

    1 Abstract ...................................................... 1
    2 Introduction .................................................. 2
    3 The SNMP Network Management Framework ......................... 2
    4 Overview ...................................................... 3
    4.1 Relationship to the Interfaces MIB .......................... 3
    4.1.1 Layering Model ............................................ 3
    4.1.2 ifRcvAddressTable ......................................... 4
    4.1.3 ifEntry ................................................... 4
    5 Definitions ................................................... 4
    6 Security Considerations ...................................... 12
    7 Acknowledgements ............................................. 12
    8 Author's Address ............................................. 12
    9 References ................................................... 13
   10 Intellectual Property Notice ................................. 15
   11 Full Copyright Statement ..................................... 16




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2.  Introduction

   Over the past several years, there have been a number of "tunneling"
   protocols specified by the IETF (see [28] for an early discussion of
   the model and examples).  This document describes a Management
   Information Base (MIB) used for managing tunnels of any type over
   IPv4 networks, including GRE [16,17], IP-in-IP [18], Minimal
   Encapsulation [19], L2TP [20], PPTP [21], L2F [25], UDP (e.g., [26]),
   ATMP [22], and IPv6-in-IPv4 [27] tunnels.

   Extension MIBs may be designed for managing protocol-specific
   objects.  Likewise, extension MIBs may be designed for managing
   security-specific objects (e.g., IPSEC [24]), and traffic conditioner
   [29] objects.  Finally, this MIB does not support tunnels over non-
   IPv4 networks (including IPv6 networks).  Management of such tunnels
   may be supported by other MIBs.

3.  The SNMP Network Management Framework

   The SNMP Management Framework presently consists of five major
   components:

   o    An overall architecture, described in RFC 2571 [1].

   o    Mechanisms for describing and naming objects and events for the
        purpose of management. The first version of this Structure of
        Management Information (SMI) is called SMIv1 and described in
        STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The
        second version, called SMIv2, is described in STD 58, RFC 2578
        [5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7].

   o    Message protocols for transferring management information. The
        first version of the SNMP message protocol is called SNMPv1 and
        described in STD 15, RFC 1157 [8]. A second version of the SNMP
        message protocol, which is not an Internet standards track
        protocol, is called SNMPv2c and described in RFC 1901 [9] and
        RFC 1906 [10].  The third version of the message protocol is
        called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and
        RFC 2574 [12].

   o    Protocol operations for accessing management information. The
        first set of protocol operations and associated PDU formats is
        described in STD 15, RFC 1157 [8]. A second set of protocol
        operations and associated PDU formats is described in RFC 1905
        [13].






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   o    A set of fundamental applications described in RFC 2573 [14] and
        the view-based access control mechanism described in RFC 2575
        [15].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the mechanisms defined in the SMI.

   This memo specifies a MIB module that is compliant to the SMIv2. A
   MIB conforming to the SMIv1 can be produced through the appropriate
   translations. The resulting translated MIB must be semantically
   equivalent, except where objects or events are omitted because no
   translation is possible (use of Counter64). Some machine readable
   information in SMIv2 will be converted into textual descriptions in
   SMIv1 during the translation process. However, this loss of machine
   readable information is not considered to change the semantics of the
   MIB.

4.  Overview

   This MIB module contains two tables:

   o    the Tunnel Interface Table, containing information on the
        tunnels known to a router; and

   o    the Tunnel Config Table, which can be used for dynamic creation
        of tunnels, and also provides a mapping from endpoint addresses
        to the current interface index value.

4.1.  Relationship to the Interfaces MIB

   This section clarifies the relationship of this MIB to the Interfaces
   MIB [23].  Several areas of correlation are addressed in the
   following subsections.  The implementor is referred to the Interfaces
   MIB document in order to understand the general intent of these
   areas.

4.1.1.  Layering Model

   Each logical interface (physical or virtual) has an ifEntry in the
   Interfaces MIB [23].  Tunnels are handled by creating a logical
   interface (ifEntry) for each tunnel. These are then correlated, using
   the ifStack table of the Interfaces MIB, to those interfaces on which
   the local IPv4 addresses of the tunnels are configured.  The basic
   model, therefore, looks something like this (for example):






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RFC 2667                     IP Tunnel MIB                   August 1999


         | |         | |          | |
      +--+ +---+  +--+ +---+      | |
      |IP-in-IP|  |  GRE   |      | |
      | tunnel |  | tunnel |      | |
      +--+ +---+  +--+ +---+      | |
         | |         | |          | |    <== attachment to underlying
      +--+ +---------+ +----------+ +--+     interfaces, to be provided
      |       Physical interface       |     by ifStack table
      +--------------------------------+

4.1.2.  ifRcvAddressTable

   The ifRcvAddressTable usage is defined in the MIBs defining the
   encapsulation below the network layer.  For example, if IP-in-IP
   encapsulation is being used, the ifRcvAddressTable is defined by IP-
   in-IP.

4.1.3.  ifEntry

   IfEntries are defined in the MIBs defining the encapsulation below
   the network layer.  For example, if IP-in-IP encapsulation [20] is
   being used, the ifEntry is defined by IP-in-IP.

   The ifType of a tunnel should be set to "tunnel" (131).  An entry in
   the IP Tunnel MIB will exist for every ifEntry with this ifType.  An
   implementation of the IP Tunnel MIB may allow ifEntries to be created
   via the tunnelConfigTable.  Creating a tunnel will also add an entry
   in the ifTable and in the tunnelIfTable, and deleting a tunnel will
   likewise delete the entry in the ifTable and the tunnelIfTable.

   The use of two different tables in this MIB was an important design
   decision.  Traditionally, ifIndex values are chosen by agents, and
   are permitted to change across restarts.  Allowing row creation
   directly in the Tunnel Interface Table, indexed by ifIndex, would
   complicate row creation and/or cause interoperability problems (if
   each agent had special restrictions on ifIndex). Instead, a separate
   table is used which is indexed only by objects over which the manager
   has control.  Namely, these are the addresses of the tunnel endpoints
   and the encapsulation protocol.  Finally, an additional manager-
   chosen ID is used in the index to support protocols such as L2F which
   allow multiple tunnels between the same endpoints.










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RFC 2667                     IP Tunnel MIB                   August 1999


5.  Definitions

TUNNEL-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, transmission,
    Integer32, IpAddress             FROM SNMPv2-SMI
    RowStatus                        FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP  FROM SNMPv2-CONF
    ifIndex, InterfaceIndexOrZero    FROM IF-MIB;

tunnelMIB MODULE-IDENTITY
    LAST-UPDATED "9908241200Z" -- August 24, 1999
    ORGANIZATION "IETF Interfaces MIB Working Group"
    CONTACT-INFO
            " Dave Thaler
              Microsoft Corporation
              One Microsoft Way
              Redmond, WA  98052-6399
              EMail: [e-mail]"
    DESCRIPTION
            "The MIB module for management of IP Tunnels, independent of
            the specific encapsulation scheme in use."
    REVISION     "9908241200Z" -- August 24, 1999
    DESCRIPTION
            "Initial version, published as RFC 2667."
    ::= { transmission 131 }

tunnelMIBObjects OBJECT IDENTIFIER ::= { tunnelMIB 1 }

tunnel      OBJECT IDENTIFIER ::= { tunnelMIBObjects 1 }

-- the IP Tunnel MIB-Group
--
-- a collection of objects providing information about
-- IP Tunnels

tunnelIfTable OBJECT-TYPE
    SYNTAX     SEQUENCE OF TunnelIfEntry
    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "The (conceptual) table containing information on configured
            tunnels."
    ::= { tunnel 1 }

tunnelIfEntry OBJECT-TYPE
    SYNTAX     TunnelIfEntry



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RFC 2667                     IP Tunnel MIB                   August 1999


    MAX-ACCESS not-accessible
    STATUS     current
    DESCRIPTION
            "An entry (conceptual row) containing the information on a
            particular configured tunnel."
    INDEX      { ifIndex }
    ::= { tunnelIfTable 1 }

TunnelIfEntry ::= SEQUENCE {
    tunnelIfLocalAddress            IpAddress,
    tunnelIfRemoteAddress           IpAddress,
    tunnelIfEncapsMethod            INTEGER,
    tunnelIfHopLimit                Integer32,
    tunnelIfSecurity                INTEGER,