RFC 1247 (rfc1247) - Page 1 of 189

OSPF Version 2

Network Working Group                                             J. Moy
Request for Comments: 1247                                 Proteon, Inc.
Obsoletes: RFC 1131                                            July 1991


                             OSPF Version 2



Status of this Memo

This RFC specifies an IAB standards track protocol for the Internet
community, and requests discussion and suggestions for improvements.
Please refer to the current edition of the ``IAB Official Protocol
Standards'' 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 based 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.  Separate routes can be calculated for each IP
type of service.  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.

Version 1 of the OSPF protocol was documented in RFC 1131.  The
differences between the two versions are explained in Appendix F.

Please send comments to .


1. Introduction

This document is a specification of the Open Shortest Path First (OSPF)
internet routing protocol.  OSPF is classified as an Internal Gateway
Protocol (IGP).  This means that it distributes routing information
between routers belonging to a single Autonomous System.  The OSPF
protocol is based on SPF or link-state technology.  This is a departure



[Moy]