OSPF Standardization Report
RFC 2329

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Network Working Group                                             J. Moy
Request for Comments: 2329                   Ascend Communications, Inc.
Category: Informational                                       April 1998

                      OSPF Standardization Report

Status of this Memo

    This memo provides information for the Internet community.  It does
    not specify an Internet standard of any kind.  Distribution of this
    memo is unlimited.

Copyright Notice

    Copyright (C) The Internet Society (1998).  All Rights Reserved.

Abstract

    This memo documents how the requirements for advancing a routing
    protocol to Full Standard, set out in [Ref2], have been met for
    OSPFv2.

    Please send comments to ospf@gated.cornell.edu.

Table of Contents

    1        Introduction ........................................... 2
    2        Modifications since Draft Standard status .............. 3
    2.1      Point-to-MultiPoint interface .......................... 4
    2.2      Cryptographic Authentication ........................... 5
    3        Updated implementation and deployment experience ....... 5
    4        Protocol Security ...................................... 7
             References ............................................. 8
             Security Considerations ................................ 8
             Author's Address ....................................... 8
             Full Copyright Statement ............................... 9

Moy                          Informational                      [Page 1]
RFC 2329              OSPF Standardization Report             April 1998

1.  Introduction

    OSPFv2, herein abbreviated simply as OSPF, is an IPv4 routing
    protocol documented in [Ref8]. OSPF is a link-state routing
    protocol.  It is designed to be run internal to a single Autonomous
    System.  Each OSPF router maintains an identical database describing
    the Autonomous System's topology.  From this database, a routing
    table is calculated by constructing a shortest-path tree. OSPF
    features include the following:

    o   OSPF responds quickly to topology changes, expending a minimum
        of network bandwidth in the process.

    o   Support for CIDR addressing.

    o   OSPF routing exchanges can be authenticated, providing routing
        security.

    o   Equal-cost multipath.

    o   An area routing capability is provided, enabling an Autonomous
        system to be split into a two level hierarchy to further reduce
        the amount of routing protocol traffic.

    o   OSPF allows import of external routing information into the
        Autonomous System, including a tagging feature that can be
        exploited to exchange extra information at the AS boundary (see
        [Ref7]).

    An analysis of OSPF together with a more detailed description of
    OSPF features was originally provided in [Ref6], as a part of
    promoting OSPF to Draft Standard status. The analysis of OSPF
    remains unchanged. Two additional major features have been developed
    for OSPF since the protocol achieved Draft Standard status: the
    Point-to-MultiPoint interface and Cryptographic Authentication.
    These features are described in Sections 2.1 and 2.2 respectively of
    this memo.

    The OSPF MIB is documented in [Ref4]. It is currently at Draft
    Standard status.

Moy                          Informational                      [Page 2]
RFC 2329              OSPF Standardization Report             April 1998

2.  Modifications since Draft Standard status

    OSPF became a Draft Standard with the release of RFC 1583 [Ref3].
    Implementations of the new specification in [Ref8] are backward-
    compatible with RFC 1583. The differences between the two documents
    are described in the Appendix Gs of [Ref1] and [Ref8]. These
    differences are listed briefly below. Two major features were also
    added, the Point-to-MultiPoint interface and Cryptographic
    Authentication, which are described in separate sections.

    o   Configuration requirements for OSPF area address ranges have
        been relaxed to allow greater flexibility in area assignment.
        See Section G.3 of [Ref1] for details.

    o   The OSPF flooding algorithm was modified to a) improve database
        convergence in networks with low speed links b) resolve a
        problem where unnecessary LSA retransmissions could occur as a
        result of differing clock granularities, c) remove race
        conditions between the flooding of MaxAge LSAs and the Database
        Exchange process, d) clarify the use of the MinLSArrival
        constant, and e) rate-limit the response to less recent LSAs
        received via flooding.  See Sections G.4 and G.5 of [Ref1] and
        Section G.1 of [Ref8] for details.

    o   To resolve the long-standing confusion regarding representation
        of point-to-point links in OSPF, the specification now
        optionally allows advertisement of a stub link to a point-to-
        point link's subnet, ala RIP. See Section G.6 of [Ref1].

    o   Several problems involving advertising the same external route
        from multiple areas were found and fixed, as described in
        Section G.7 of [Ref1] and Section G.2 of [Ref8].  Without the
        fixes, persistent routing loops could form in certain such