Extended Message Support for BGP
RFC 8654

Document Type RFC - Proposed Standard (October 2019; No errata)
Updates RFC 4271
Last updated 2019-10-24
Replaces draft-ymbk-bgp-extended-messages
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Susan Hares
Shepherd write-up Show (last changed 2019-07-08)
IESG IESG state RFC 8654 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Alvaro Retana
Send notices to jgs@juniper.net, jie.dong@huawei.com, aretana.ietf@gmail.com
IANA IANA review state IANA OK - Actions Needed
IANA action state RFC-Ed-Ack


Internet Engineering Task Force (IETF)                           R. Bush
Request for Comments: 8654                                  Arrcus & IIJ
Updates: 4271                                                   K. Patel
Category: Standards Track                                   Arrcus, Inc.
ISSN: 2070-1721                                                  D. Ward
                                                           Cisco Systems
                                                            October 2019

                    Extended Message Support for BGP

Abstract

   The BGP specification (RFC 4271) mandates a maximum BGP message size
   of 4,096 octets.  As BGP is extended to support new Address Family
   Identifiers (AFIs), Subsequent AFIs (SAFIs), and other features,
   there is a need to extend the maximum message size beyond 4,096
   octets.  This document updates the BGP specification by extending the
   maximum message size from 4,096 octets to 65,535 octets for all
   messages except for OPEN and KEEPALIVE messages.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8654.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
     1.1.  Requirements Language
   2.  BGP Extended Message
   3.  BGP Extended Message Capability
   4.  Operation
   5.  Error Handling
   6.  Changes to RFC 4271
   7.  IANA Considerations
   8.  Security Considerations
   9.  References
     9.1.  Normative References
     9.2.  Informative References
   Acknowledgments
   Authors' Addresses

1.  Introduction

   The BGP specification [RFC4271] mandates a maximum BGP message size
   of 4,096 octets.  As BGP is extended to support new AFIs, SAFIs, and
   other capabilities (e.g., BGPsec [RFC8205] and BGP - Link State (BGP-
   LS) [RFC7752]), there is a need to extend the maximum message size
   beyond 4,096 octets.  This document provides an extension to BGP to
   extend the message size limit from 4,096 octets to 65,535 octets for
   all messages except for OPEN and KEEPALIVE messages.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  BGP Extended Message

   A BGP message over 4,096 octets in length is a BGP Extended Message.

   BGP Extended Messages have a maximum message size of 65,535 octets.
   The smallest message that may be sent is a BGP KEEPALIVE, which
   consists of 19 octets.

3.  BGP Extended Message Capability

   The BGP Extended Message Capability is a new BGP capability [RFC5492]
   defined with Capability Code 6 and Capability Length 0.

   To advertise the BGP Extended Message Capability to a peer, a BGP
   speaker uses BGP Capabilities Advertisement [RFC5492].  By
   advertising the BGP Extended Message Capability to a peer, a BGP
   speaker conveys that it is able to receive and properly handle BGP
   Extended Messages (see Section 4).

   Peers that wish to use the BGP Extended Message Capability MUST
   support error handling for BGP UPDATE messages per [RFC7606].

4.  Operation

   The BGP Extended Message Capability applies to all messages except
   for OPEN and KEEPALIVE messages.  These exceptions reduce the
   complexity of providing backward compatibility.

   A BGP speaker that is capable of receiving BGP Extended Messages
   SHOULD advertise the BGP Extended Message Capability to its peers
   using BGP Capabilities Advertisement [RFC5492].  A BGP speaker MAY
   send BGP Extended Messages to a peer only if the BGP Extended Message
   Capability was received from that peer.

   An implementation that advertises the BGP Extended Message Capability
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