Browse Prior Art Database

Border Gateway Protocol (BGP) Persistent Route Oscillation Condition (RFC3345)

IP.com Disclosure Number: IPCOM000009222D
Original Publication Date: 2002-Aug-01
Included in the Prior Art Database: 2002-Aug-13
Document File: 20 page(s) / 38K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D. McPherson: AUTHOR [+4]

Abstract

In particular configurations, the BGP scaling mechanisms defined in "BGP Route Reflection - An Alternative to Full Mesh IBGP" and "Autonomous System Confederations for BGP" will introduce persistent BGP route oscillation. This document discusses the two types of persistent route oscillation that have been identified, describes when these conditions will occur, and provides some network design guidelines to avoid introducing such occurrences.

This text was extracted from an ASCII text file.
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Network Working Group� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � D. McPherson

Request for Comments: 3345� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � TCB

Category: Informational� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � V. Gill

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � AOL Time Warner, Inc.

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � D. Walton

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � A. Retana

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Cisco Systems, Inc.

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � August 2002

� Border Gateway Protocol (BGP) Persistent Route Oscillation Condition

Status of this Memo

� � This memo provides information for the Internet community.� It does

� � not specify an Internet standard of any kind.� Distribution of this

� � memo is unlimited.

Copyright Notice

� � Copyright (C) The Internet Society (2002).� All Rights Reserved.

Abstract

� � In particular configurations, the BGP scaling mechanisms defined in

� � "BGP Route Reflection - An Alternative to Full Mesh IBGP" and

� � "Autonomous System Confederations for BGP" will introduce persistent

� � BGP route oscillation.� This document discusses the two types of

� � persistent route oscillation that have been identified, describes

� � when these conditions will occur, and provides some network design

� � guidelines to avoid introducing such occurrences.

1. Introduction

� � The Border Gateway Protocol (BGP) is an inter-Autonomous System

� � routing protocol.� The primary function of a BGP speaking system is

� � to exchange network reachability information with other BGP systems.

� � In particular configurations, the BGP [1] scaling mechanisms defined

� � in "BGP Route Reflection - An Alternative to Full Mesh IBGP" [2] and

� � "Autonomous System Confederations for BGP" [3] will introduce

� � persistent BGP route oscillation.

� � The problem is inherent in the way BGP works: locally defined routing

� � policies may conflict globally, and certain types of conflicts can

� � cause persistent oscillation of the protocol.� Given current

� � practices, we happen to see the problem manifest itself in the

� � context of MED + route reflectors or confederations.

McPherson, et al.� � � � � � � � � � � Informational� � � � � � � � � � � � � � � � � � � � � [Page 1]

RFC 3345� � � � � � BGP Persistent Route Oscillation Condition� � � August 2002

� � The current specification of BGP-4 [4] states that the

� � MULTI_EXIT_DISC is only comparable between routes learned from the

� � same neighboring AS.� This limitation is consistent wit...