rfc2787.txt

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Network Working Group                                           B. Jewell
Request for Comments: 2787                 Copper Mountain Networks, Inc.
Category: Standards Track                                       D. Chuang
                                                    CoSine Communications
                                                               March 2000


                 Definitions of Managed Objects for the
                   Virtual Router Redundancy 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.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This specification defines an extension to the Management Information
   Base (MIB) for use with SNMP-based network management.  In
   particular, it defines objects for configuring, monitoring, and
   controlling routers that employ the Virtual Router Redundancy
   Protocol (VRRP) [17].

   This memo specifies a MIB module in a manner that is compliant with
   SMIv2 [5], and semantically identical to the SMIv1 definitions [2].



















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Table of Contents

   1  The SNMP Network Management Framework .................    2
   2  Overview ..............................................    3
   2.1  VRRP MIB Structure ..................................    3
   2.2  Virtual Router Redundancy Protocol ..................    4
   2.3  VRRP MIB Table Design ...............................    4
   2.3.1  Relation to Interface Group .......................    5
   2.4  VRRP Scenarios ......................................    5
   2.4.1  Scenario #1 .......................................    5
   2.4.2  Scenario #2 .......................................    8
   3  Definitions ...........................................   11
   4  Security Considerations ...............................   27
   5  Acknowledgements ......................................   28
   6  References ............................................   28
   7  Authors' Addresses ....................................   30
   8  Intellectual Property Statement........................   30
   9  Full Copyright Statement...............................   31

1.  The SNMP 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].

   A more detailed introduction to the current SNMP Management Framework
   can be found in RFC 2570 [16].

   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.

2.  Overview

   This memo identifies the set of objects for configuring, monitoring,
   and controlling the Virtual Router Redundancy Protocol (VRRP), as
   defined in RFC 2338 [17].

   VRRP specifies an election protocol that will allow one or more
   associated IP addresses to be assumed by another router in the event
   of a failure of the IP address(es) owner. Thus, IP traffic from a
   host using a failed router as a default gateway is transparently
   fowarded by the VRRP router that has assumed control.  VRRP provides
   redundancy in routed networks without requiring configuration of
   dynamic routing or router discovery protocols on every end-host.

   Since the VRRP protocol is intended for use with IPv4 routers only,
   this MIB uses the SYNTAX for IP addresses which is specific to IPv4.
   Thus, changes will be required for this MIB to interoperate in an
   IPv6 environment.

2.1.  VRRP MIB Structure

   The VRRP MIB contains three conformance groups:

   - vrrpOperations Group: Objects related to VRRP router's
     configuration and control.

   - vrrpStatistics Group: Objects containing information useful in
     monitoring the operation of VRRP routers.



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   - vrrpNotifications Group: Consists of objects and definitions for
     use in SNMP notifications sent by VRRP routers.

   Tables in the MIB include the following:

   (1) The vrrpOperTable, which contains objects that define the
       operational characteristics of a VRRP router. Rows in this table
       correspond to instances of virtual routers.

   (2) The vrrpAssoIpAddrTable, which contains the addresses of the
        virtual router(s) that a given VRRP router is backing up.

   (3) The vrrpRouterStatsTable which contains the operating statistics
       for a VRRP router.

2.2.  Virtual Router Redundancy Protocol

   This MIB is based on the following characteristics of VRRP as defined
   in the VRRP specification [17].

   - A "VRRP router" is one that is configured to run the VRRP protocol
     in conjunction with one or more other VRRP routers attached to a
     LAN.

   - A VRRP router can be running one or more instances of a virtual
     router.

   - A "virtual router" is an abstraction which consists of two or more
     physical routers associated by a Virtual Router Identifier (VRID).

   - An instance of a virtual router (on a physical VRRP router), can be
     uniquely identified by a combination of the 'ifIndex' [18] and
     "Virtual Router Identifier" (VRID).

   - For each VRID there is a set of one or more "associated IP
     addresses" that are backed-up by the virtual router.

2.3.  VRRP MIB Table Design

   The tables in the VRRP MIB are structured with the assumption that a
   VRRP network management application would likely be designed to
   display information or provide configuration about a VRRP router on a
   "per-virtual-router basis". Thus, the tables defined in the MIB
   consist of conceptual rows which are grouped in a manner to present a
   view of individual virtual routers with a minimal number of SNMP
   operations.





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2.3.1.  Relation to Interface Group (RFC 2233) [18].

   Since a router can be participating in VRRP on one or more physical
   interfaces, "ifIndex" is used as an index into the tables defined in
   the VRRP MIB.

2.4.  VRRP Scenarios

   The following section provides examples of how some of the objects in
   this MIB are instantiated for two different VRRP scenarios.

   KEY:
   ----

   The labels in the following tables and diagrams correspond to the
   actual MIB objects as follows:

      if      = vrrpOperIfIndex
      VrId    = vrrpOperVrId
      State   = vrrpOperState
      Prior   = vrrpOperPriority
      AddrCnt = vrrpOperIpAddrCount
      IpAddr  = vrrpOperMasterIpAddr
      RowStat = vrrpOperRowStatus

2.4.1.  VRRP Scenario #1

   The following figure shows a simple network with two VRRP routers
   configured with two virtual routers. This sample topology is taken
   from the VRRP specification [17]. Addresses in '()' indicate the IP
   address of the default gateway for a given host, H1 - H4. In the
   diagram, "Interface" is used in the context defined in IF-MIB [18].



















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                   VRID=1       VRID=2
                  +-----+      +-----+
                  | MR1 |      | MR2 |
                  |  &  |      |  &  |
                  | BR2 |      | BR1 |
                  +-----+      +-----+
     IP A ---------->*            *<---------- IP B
     Interface=I1    |            |            Interface=I2
                     |            |
                     |            |
   ------------------+------------+-----+--------+--------+--------+--
                                        ^        ^        ^        ^
                                        |        |        |        |
                                      (IP A)   (IP A)   (IP A)   (IP A)
                                        |        |        |        |
                                     +--+--+  +--+--+  +--+--+  +--+--+
                                     |  H1 |  |  H2 |  |  H3 |  |  H4 |
                                     +-----+  +-----+  +--+--+  +--+--+



            -----   MIB Tables For VRRP Router "IP A":   -----

   vrrpOperTable
   -------------

      | if | VrId | State | Prior | AddrCnt | IpAddr | ... | RowStat |
      +----+------+-------+-------+---------+--------+-( )-+---------+
      |    |      |       |       |         |        |     |         |
      | I1 |  01  |   M   |  255  |   1     |   A    |     | active  |
      |    |      |       |       |         |        |     |         |
      +----+------+-------+-------+---------+--------+-( )-+---------+
      |    |      |       |       |         |        |     |         |
      | I1 |  02  |   B   | 1-254 |   1     |   B    |     | active  |
      |    |      |       |       |         |        |     |         |
      +----+------+-------+-------+---------+--------+-( )-+---------+















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   vrrpAssoIpAddrTable
   -------------------

      | if | VrId |  IP   | RowStat |
      +----+------+-------+---------+
      |    |      |       |         |
      | I1 |  01  |   A   | active  |
      |    |      |       |         |
      +----+------+-------+---------+
      |    |      |       |         |
      | I1 |  02  |   B   | active  |
      |    |      |       |         |
      +----+------+-------+---------+



            -----   MIB Tables For VRRP Router "IP B":   -----

   vrrpOperTable
   -------------

      | if | VrId | State | Prior | AddrCnt | IpAddr | ... | RowStat |
      +----+------+-------+-------+---------+--------+-( )-+---------+
      |    |      |       |       |         |        |     |         |
      | I2 |  01  |   B   | 1-254 |    1    |   A    |     | active  |
      |    |      |       |       |         |        |     |         |
      +----+------+-------+-------+---------+--------+-( )-+---------+
      |    |      |       |       |         |        |     |         |
      | I2 |  02  |   M   |  255  |    1    |   B    |     | active  |
      |    |      |       |       |         |        |     |         |
      +----+------+-------+-------+---------+--------+-( )-+---------+

   vrrpAssoIpAddrTable
   -------------------

      | if | VrId |  IP   | RowStat |
      +----+------+-------+---------+
      |    |      |       |         |
      | I2 |  01  |   A   | active  |
      |    |      |       |         |
      +----+------+-------+---------+
      |    |      |       |         |
      | I2 |  02  |   B   | active  |
      |    |      |       |         |
      +----+------+-------+---------+






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   NOTES:

   1)  "I1" and "I2" are used to designate IF indices on each respective
       router.

   2)  For "State": M = Master; B = Backup.

   3)  In the vrrpOperTable, a "priority" of 255 indicates that the
       respective router owns the IP address, e.g., this IP address is
       native to the router (i.e., "the IP Address Owner" [17]).

2.4.2.  VRRP Scenario #2

   The following figure shows a simple network with two virtual routers.
   Here, a single interface has been configured with two IP addresses.
   Again, addresses in () indicate the IP address of the default gateway
   for a given host, H1 - H2.

                   VRID=1       VRID=2
                  +-----+      +-----+
                  | MR1 |      | MR2 |
                  |  &  |      |  &  |
                  | BR2 |      | BR1 |
                  +-----+      +-----+
     IP A ---------->*            *<---------- IP B
     IP C            |            |            Interface=I2
     Interface=I1    |            |
                     |            |
                     |            |
   ------------------+------------+-----+--------+
                                        ^        ^
                                        |        |
                                      (IP A)   (IP B)
                                        |        |
                                     +--+--+  +--+--+
                                     |  H1 |  |  H2 |
                                     +-----+  +-----+