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BGP Route Reflection - An Alternative to Full Mesh IBGP (RFC2796)

IP.com Disclosure Number: IPCOM000003395D
Original Publication Date: 2000-Apr-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 8 page(s) / 18K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

T. Bates: AUTHOR [+3]

Abstract

The Border Gateway Protocol [1] is an inter-autonomous system routing protocol designed for TCP/IP internets. Currently in the Internet 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 text was extracted from a ASCII Text document.
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Network Working Group T. Bates

Request for Comments: 2796 Cisco Systems

Updates: 1966 R. Chandra

Category: Standards Track E. Chen

Redback Networks

April 2000

BGP Route Reflection -

An Alternative to Full Mesh IBGP

Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2000). All Rights Reserved.

Abstract

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

protocol designed for TCP/IP internets. Currently in the Internet 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. For n BGP speakers within an AS that

requires to maintain n*(n-1)/2 unique IBGP sessions. This "full

mesh" requirement clearly does not scale when there are a large

number of IBGP speakers each exchanging a large volume of routing

information, as is common in many of todays internet networks.

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". This approach allows a BGP

speaker (known as "Route Reflector") to advertise IBGP learned routes

to certain IBGP peers. It represents a change in the commonly

understood concept of IBGP, and the addition of two new optional

transitive BGP attributes to prevent loops in routing updates.

This document is a revision of RFC1966 [4], and it includes editorial

changes, clarifications and corrections based on the deployment

experience with route reflection. These revisions are summarized in

the Appendix.

2. Design Criteria

Route Reflection was designed to satisfy the following criteria.

...