Browse Prior Art Database

BGP Route Reflection An alternative to full mesh IBGP (RFC1966)

IP.com Disclosure Number: IPCOM000004254D
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

T. Bates & R. Chandrasekeran: AUTHOR

Abstract

The Border Gateway Protocol [1] is an inter-autonomous system routing protocol designed for TCP/IP internets. BGP deployments are configured such that that all BGP speakers within a single AS must be fully meshed so that any external routing information must be re- distributed to all other routers within that AS. This represents a serious scaling problem that has been well documented with several alternatives proposed [2,3].

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This is the abbreviated version, containing approximately 20% of the total text.

Network Working Group T. Bates

Request for Comments: 1966 cisco Systems

Category: Experimental R. Chandra

cisco Systems

June 1996

BGP Route Reflection

An alternative to full mesh IBGP

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.

Abstract

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

protocol designed for TCP/IP internets. BGP deployments are

configured such that that all BGP speakers within a single AS must be

fully meshed so that any external routing information must be re-

distributed to all other routers within that AS. This represents a

serious scaling problem that has been well documented with several

alternatives proposed [2,3].

This document describes the use and design of a method known as

"Route Reflection" to alleviate the the need for "full mesh" IBGP.

1. Introduction

Currently in the Internet, BGP deployments are configured such that

that all BGP speakers within a single AS must be fully meshed and any

external routing information must be re-distributed to all other

routers within that AS. This "full mesh" requirement clearly does not

scale when there are a large number of IBGP speakers as is common in

many of todays internet networks.

For n BGP speakers within an AS you must maintain n*(n-1)/2 unique

IBGP sessions. With finite resources in both bandwidth and router CPU

this clearly does not scale.

This scaling problem has been well documented and a number of

proposals have been made to alleviate this [2,3]. This document

represents another alternative in alleviating the need for a "full

mesh" and is known as "Route Reflection". It represents a change in

the commonly understood concept of IBGP and the addition of two new

optional transitive BGP attributes.

2. Design Criteria

Route Reflection was designed to satisfy the following criteria.

o Simplicity

Any alternative must be both simple to configure as well

as understand.

o Easy Migration

It must be possible to migrate from a full mesh

configuration without the need to change either topology

or AS. T...