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Autonomous System Confederations for BGP (RFC1965)

IP.com Disclosure Number: IPCOM000004189D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 6 page(s) / 13K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

P. Traina: AUTHOR


Border Gateway Protocol [1] is an inter-autonomous system routing protocol designed for TCP/IP networks.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 22% of the total text.

Network Working Group P. Traina

Request for Comments: 1965 cisco Systems

Category: Experimental June 1996

Autonomous System Confederations for BGP

Status of this Memo

This memo defines an Experimental Protocol for the Internet

community. This memo does not specify an Internet standard of any

kind. Discussion and suggestions for improvement are requested.

Distribution of this memo is unlimited.


Border Gateway Protocol [1] is an inter-autonomous system routing

protocol designed for TCP/IP networks.

This document describes an extension to BGP which may be used to

create a confederation of autonomous systems which is represented as

one single autonomous system to BGP peers external to the


The intention of this extension is to aid in policy administration

and reduce the management complexity of maintaining a large

autonomous system.

The extension this document describes is widely deployed in the

Internet today.


It may be useful to subdivide autonomous systems with a very large

number of BGP speakers into smaller domains for purposes of

controlling routing policy via information contained in the BGP

AS_PATH attribute. For example, one may chose to consider all BGP

speakers in a geographic region as a single entity.

In addition to improvements in routing policy control, current

techniques for deploying BGP among speakers in the same autonomous

system establish a full mesh of TCP connections among all speakers

for the purpose of exchanging exterior routing information. In

autonomous systems the number of intra-domain connections that need

to be maintained by each border router can become significant.

Subdividing a large autonomous system allows a significant reduction

in the total number of intra-domain BGP connections, as the

connectivity requirements simplify to the model used for inter-domain


Unfortunately subdividing an autonomous system may increase the

complexity of policy routing based on AS_PATH information for all

members of the Internet. Additionally, this division increases the

maintenance overhead of coordinating external peering when the

internal topology of this collection of autonomous systems is


Finally, dividing a large AS may unnecessarily increase the length of

the sequence portions of the AS_PATH attribute. Several common BGP

implementations can use the number of "hops" required to reach a

given destination as part ...