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OSPF Protocol Analysis (RFC1245)

IP.com Disclosure Number: IPCOM000002061D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2001-Oct-24
Document File: 12 page(s) / 27K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Moy: AUTHOR

Abstract

This is the first of two reports on the OSPF protocol. These reports are required by the IAB/ IESG in order for an Internet routing protocol to advance to Draft Standard Status. OSPF is a TCP/IP routing protocol, designed to be used internal to an Autonomous System (in other words, OSPF is an Interior Gateway Protocol). (Download file contains alternative document formats.)

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 12% of the total text.

Network Working Group                                     J. Moy, Editor

Request for Comments: 1245                                 Proteon, Inc.

                                                               July 1991

                         OSPF protocol analysis

Status of this Memo

This memo provides information for the Internet community. It does not

specify any Internet standard. Distribution of this memo is unlimited.

Please send comments to ospf@trantor.umd.edu.

Abstract

This is the first of two reports on the OSPF protocol. These reports are

required by the IAB/ IESG in order for an Internet routing protocol to

advance to Draft Standard Status. OSPF is a TCP/IP routing protocol,

designed to be used internal to an Autonomous System (in other words,

OSPF is an Interior Gateway Protocol).

Version 1 of the OSPF protocol was published in RFC 1131. Since then

OSPF version 2 has been developed. Version 2 has been documented in RFC

1247.  The changes between version 1 and version 2 of the OSPF protocol

are explained in Appendix F of RFC 1247. It is OSPF Version 2 that is

the subject of this report.

This report attempts to summarize the key features of OSPF V2. It also

attempts to analyze how the protocol will perform and scale in the

Internet.

1.0  Introduction

This document addresses, for OSPF V2, the requirements set forth by the

IAB/IESG for an Internet routing protocol to advance to Draft Standard

state. This requirements are briefly summarized below. The remaining

sections of this report document how OSPF V2 satisfies these

requirements:

o  What are the key features and algorithms of the protocol?

o  How much link bandwidth, router memory and router CPU cycles does the

   protocol consume under normal conditions?

o  For these metrics, how does the usage scale as the routing

   environment grows? This should include topologies at least an order

[Moy]                                                           [Page 1]

RFC 1245                 OSPF protocol analysis                July 1991

   of magnitude larger than the current environment.

o  What are the limits of the protocol for these metrics? (I.e., when

   will the routing protocol break?)

o  For what environments is the protocol well suited, and for what is it

   not suitable?

1.1  Acknowledgments

The OSPF protocol has been developed by the OSPF Working Group of the

Internet Engineering Task Force.

2.0  Key features of the OSPF protocol

This section summarizes the key features of the OSPF protocol. OSPF is

an Internal gateway protocol; it is designed to be used internal to a

single Autonomous System. OSPF uses link-state or SPF-based technology

(as compared to the distance-vector or Bellman-Ford technology found in

routing protocols such as RIP). Individual link state advertisements

(LSAs) describe pieces of the OSPF routing domain (Autonomous System).

These LSAs are flooded throughout the routing domain, forming the link

state database. Each router has an identical link state database;

synchronization of link state databases is maintained via a reliable

flooding algorithm. From this link state database, each router builds a

routing table by calculating a shortest-path tree, with the root of the

tree being the calculating router itself. This cal...