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OSPF Version 2 (RFC2178)

IP.com Disclosure Number: IPCOM000002736D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2000-Sep-13

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.

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Network Working Group J. Moy

Request for Comments: 2178 Cascade Communications Corp.

Obsoletes: 1583 July 1997

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.

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 1583 are explained in

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

Implementations of this memo and of RFC 1583 will interoperate.

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

Table of Contents

1 Introduction ........................................... 5

1.1 Protocol Overview ...................................... 5

1.2 Definitions of commonly used terms ..................... 6

1.3 Brief history of link-state routing technology ........ 9

1.4 Organization of this document ......................... 10

1.5 Acknowledgments ....................................... 11

2 The link-state database: organization and calculations 11

2.1 Representation of routers and networks ................ 11

2.1.1 Representation of non-broadcast networks .............. 13

2.1.2 An example link-state database ........................ 14

2.2 The shortest-path tree ................................ 18

2.3 Use of external routing information ................... 20

2.4 Equal-cost multipath .................................. 22

3 Splitting the AS into Areas ........................... 22

...