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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.
This is the abbreviated version, containing approximately 7% of the total text.

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...