Autonomous System Confederations for BGP
RFC 3065
Document | Type |
RFC - Proposed Standard
(February 2001; Errata)
Obsoleted by RFC 5065
Obsoletes RFC 1965
|
|
---|---|---|---|
Authors | Paul Traina , John Scudder , Danny McPherson | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3065 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group P. Traina Request for Comments: 3065 Juniper Networks, Inc. Obsoletes: 1965 D. McPherson Category: Standards Track Amber Networks, Inc. J. Scudder Cisco Systems, Inc. February 2001 Autonomous System Confederations for BGP 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 (2001). All Rights Reserved. Abstract The Border Gateway Protocol (BGP) is an inter-autonomous system routing protocol designed for Transmission Control Protocol/Internet Protocol (TCP/IP) networks. BGP requires that all BGP speakers within a single autonomous system (AS) must be fully meshed. This represents a serious scaling problem that has been well documented in a number of proposals. This document describes an extension to BGP which may be used to create a confederation of autonomous systems that is represented as a single autonomous system to BGP peers external to the confederation, thereby removing the "full mesh" requirement. The intention of this extension is to aid in policy administration and reduce the management complexity of maintaining a large autonomous system. 1. Specification of Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119]. Traina, et al. Standards Track [Page 1] RFC 3065 Autonomous System Confederations for BGP February 2001 2. Introduction As currently defined, BGP requires that all BGP speakers within a single AS must be fully meshed. The result is that for n BGP speakers within an AS n*(n-1)/2 unique IBGP sessions are required. This "full mesh" requirement clearly does not scale when there are a large number of IBGP speakers within the autonomous system, as is common in many networks today. This scaling problem has been well documented and a number of proposals have been made to alleviate this [3,5]. This document represents another alternative in alleviating the need for a "full mesh" and is known as "Autonomous System Confederations for BGP", or simply, "BGP Confederations". It can also be said the BGP Confederations MAY provide improvements in routing policy control. This document is a revision of RFC 1965 [4] and it includes editorial changes, clarifications and corrections based on the deployment experience with BGP Confederations. These revisions are summarized in Appendix A. 3. Terms and Definitions AS Confederation A collection of autonomous systems advertised as a single AS number to BGP speakers that are not members of the confederation. AS Confederation Identifier An externally visible autonomous system number that identifies the confederation as a whole. Member-AS An autonomous system that is contained in a given AS confederation. Member-AS Number An autonomous system number visible only internal to a BGP confederation. 4. Discussion 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 Traina, et al. Standards Track [Page 2] RFC 3065 Autonomous System Confederations for BGP February 2001 AS_PATH attribute. For example, one may choose to consider all BGP speakers in a geographic region as a single entity. In addition to potential improvements in routing policy control, if techniques such as those presented here or in [5] are not employed, [1] requires BGP speakers in the same autonomous system to 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 connections. Unfortunately subdividing an autonomous system may increase theShow full document text