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OSPF Version 2 (RFC2328)

IP.com Disclosure Number: IPCOM000002895D
Original Publication Date: 1998-Apr-01
Included in the Prior Art Database: 2001-Nov-12

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Moy: AUTHOR

Abstract

This memo documents version 2 of the OSPF protocol. 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.

This text was extracted from an ASCII text file.
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Network Working Group                                             J. Moy

Request for Comments: 2328                   Ascend Communications, Inc.

STD: 54                                                       April 1998

Obsoletes: 2178

Category: Standards Track

                             OSPF Version 2

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 (1998).  All Rights Reserved.

Abstract

    This memo documents version 2 of the OSPF protocol.  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 recalculates routes quickly in the face of topological changes,

    utilizing a minimum of routing protocol traffic.  OSPF provides

    support for equal-cost multipath.  An area routing capability is

    provided, enabling an additional level of routing protection and a

    reduction in routing protocol traffic.  In addition, all OSPF

    routing protocol exchanges are authenticated.

    The differences between this memo and RFC 2178 are explained in

    Appendix G. All differences are backward-compatible in nature.

Moy                         Standards Track                     [Page 1]

RFC 2328                     OSPF Version 2                   April 1998

    Implementations of this memo and of RFCs 2178, 1583, and 1247 will

    interoperate.

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

Table of Contents

    1        Introduction ........................................... 6

    1.1      Protocol Overview ...................................... 6

    1.2      Definitions of commonly used terms ..................... 8

    1.3      Brief history of link-state routing technology ........ 11

    1.4      Organization of this document ......................... 12

    1.5      Acknowledgments ....................................... 12

    2        The link-state database: organization and calculations  13

    2.1      Representation of routers and networks ................ 13

    2.1.1    Representation of non-broadcast networks .............. 15

    2.1.2    An example link-state database ........................ 18

    2.2      The shortest-path tree ................................ 21

    2.3      Use of external routing information ................... 23

    2.4      Equal-cost multipath .................................. 26

    3        Splitting the AS into Areas ........................... 26

    3.1      The backbone of the Autonomous System ................. 27

    3.2      Inter-area routing .................................... 27

    3.3      Classification of routers ............................. 28

    3.4      A sample area configuration ........................... 29

    3.5      IP subnetting support ................................. 35

    3.6      Supporting stub areas ................................. 37

    3.7      Partitions of areas ................................... 38

    4        Functional Summary .....