Browse Prior Art Database

BGP-4 Protocol Analysis (RFC1774)

IP.com Disclosure Number: IPCOM000004026D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 8 page(s) / 22K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

P. Traina: AUTHOR [+2]

Abstract

The purpose of this report is to document how the requirements for advancing a routing protocol to Draft Standard have been satisfied by the Border Gateway Protocol version 4 (BGP-4). This report summarizes the key features of BGP, and analyzes the protocol with respect to scaling and performance. This is the first of two reports on the BGP protocol.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 13% of the total text.

Network Working Group P. Traina, Editor

Request for Comments: 1774 cisco Systems

Category: Informational March 1995

BGP-4 Protocol Analysis

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.

Introduction

The purpose of this report is to document how the requirements for

advancing a routing protocol to Draft Standard have been satisfied by

the Border Gateway Protocol version 4 (BGP-4). This report summarizes

the key features of BGP, and analyzes the protocol with respect to

scaling and performance. This is the first of two reports on the BGP

protocol.

BGP-4 is an inter-autonomous system routing protocol designed for

TCP/IP internets. Version 1 of the BGP protocol was published in RFC

1105. Since then BGP versions 2, 3, and 4 have been developed.

Version 2 was documented in RFC 1163. Version 3 is documented in

RFC1267. The changes between versions are explained in Appendix 2 of

[1].

Possible applications of BGP in the Internet are documented in [2].

Please send comments to iwg@ans.net.

Key features and algorithms of the BGP-4 protocol.

This section summarizes the key features and algorithms of the BGP

protocol. BGP is an inter-autonomous system routing protocol; it is

designed to be used between multiple autonomous systems. BGP assumes

that routing within an autonomous system is done by an intra-

autonomous system routing protocol. BGP does not make any assumptions

about intra-autonomous system routing protocols employed by the

various autonomous systems. Specifically, BGP does not require all

autonomous systems to run the same intra-autonomous system routing

protocol.

BGP is a real inter-autonomous system routing protocol. It imposes no

constraints on the underlying Internet topology. The information

exchanged via BGP is sufficient to construct a graph of autonomous

systems connectivity from which routing loops may be pruned and some

routing policy decisions at the autonomous system level may be

enforced.

The key features of the protocol are the notion of path attributes

and aggregation of network layer reachability information (NLRI).

Path attributes provide BGP with flexibility and expandability. Path

attributes are partitioned into well-known and optional. The

provision for optional attributes allows experimentation that may

involve a group of BGP routers without affecting the rest of the

Internet. New optional attributes can be added to the protocol in

much the same fashion as new options are added to the Telnet

protocol, for instance.

One of the most important path attributes is the AS-PATH. AS

reachability information traverses the Internet, this information is

augmented by the list of autonomous systems...