Network Working Group R. Bush
Internet-Draft Internet Initiative Japan
Updates: 4271 (if approved) K. Patel
Intended status: Standards Track D. Ward
Expires: November 22, 2016 Cisco Systems
May 21, 2016
Extended Message support for BGP
draft-ietf-idr-bgp-extended-messages-12
Abstract
The BGP specification mandates a maximum BGP message size of 4096
octets. As BGP is extended to support newer AFI/SAFIs, there is a
need to extend the maximum message size beyond 4096 octets. This
document updates the BGP specification in RFC4271 by providing an
extension to BGP to extend its current message size from 4096 octets
to 65535 octets.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
be interpreted as described in RFC 2119 [RFC2119] only when they
appear in all upper case. They may also appear in lower or mixed
case as English words, without normative meaning.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 22, 2016.
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Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BGP Extended Message . . . . . . . . . . . . . . . . . . . . 2
3. Extended message Capability for BGP . . . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 3
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Security Considerations . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
9.1. Normative References . . . . . . . . . . . . . . . . . . 4
9.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The BGP specification RFC4271 [RFC4271] mandates a maximum BGP
message size of 4096 octets. As BGP is extended to support newer
AFI/SAFIs and newer capabilities (e.g.,
[I-D.ietf-sidr-bgpsec-overview]), there is a need to extend the
maximum message size beyond 4096 octets. This draft provides an
extension to BGP to extend its current message size limit from 4096
octets to 65535 octets.
2. BGP Extended Message
A BGP message over 4096 octets in length is a BGP Extended Message.
BGP Extended Messages have maximum message size of 65535 octets. The
smallest message that may be sent consists of a BGP header without a
data portion (19 octets).
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Multi-octet fields MUST be in network byte order.
3. Extended message Capability for BGP
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 send, receive, and properly handle
BGP Extended Messages.
A peer which does not advertise this capability MUST NOT send BGP
Extended Messages, and BGP Extended Messages MUST NOT be sent to it.
The BGP Extended Message Capability is a new BGP Capability [RFC5492]
defined with Capability code TBD and Capability length 0.
4. Operation
A BGP speaker that is willing to send and receive BGP Extended
Messages from its peer should advertise the BGP Extended Message
Capability to its peer using BGP Capabilities Advertisement
[RFC5492]. A BGP speaker may send extended messages to its peer only
if it has received the Extended Message Capability from its peer.
An implementation that supports the BGP Extended Messages MUST be
prepared to receive an OPEN message that is larger than 4096 bytes.
Applications generating messages which might be encapsulated within
BGP messages MUST limit the size of their payload to take into
account the maximum message size and all encapsulation overheads on
the path the encapsulated data are expected to traverse.
5. Error Handling
A BGP speaker that has the ability to use extended messages but has
not advertised the BGP Extended Messages capability, presumably due
to configuration, SHOULD NOT accept an extended message. A speaker
MAY implement a more liberal policy and accept extended messages even
from a peer that has not advertised the capability.
However, a BGP speaker that does not advertise the BGP Extended
Messages capability might also genuinely not support extended
messages. Such a speaker would be expected to follow the error
handling procedures of [RFC4221], Section 6.1, and reset the session
with a Bad Message Length NOTIFICATION if it receives an extended
message. A speaker that treats an improper extended message as a
fatal error, as described in the preceding paragraph, MUST do
likewise.
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6. Acknowledgements
The authors thank Enke Chen, Susan Hares, John Scudder, John Levine,
and Job Snijders for their input.
7. IANA Considerations
The IANA is requested to register a new BGP Capability Code to be
named BGP Extended Message Capability and referring to this document.
Registry: BGP Capability Code
Value Description Document
----- ----------------------------------- -------------
64 Graceful Restart Capability [RFC4724]
....
72 CP-ORF Capability [RFC7543]
...
TBD BGP-Extended Message [this draft]
8. Security Considerations
This extension to BGP does not change BGP's underlying security
issues.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4221] Nadeau, T., Srinivasan, C., and A. Farrel, "Multiprotocol
Label Switching (MPLS) Management Overview", RFC 4221,
November 2005.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, February 2009.
9.2. Informative References
[I-D.ietf-sidr-bgpsec-overview]
Lepinski, M. and S. Turner, "An Overview of BGPSEC",
draft-ietf-sidr-bgpsec-overview-02 (work in progress), May
2012.
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Authors' Addresses
Randy Bush
Internet Initiative Japan
5147 Crystal Springs
Bainbridge Island, Washington 98110
US
Email: randy@psg.com
Keyur Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
Dave Ward
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: dward@cisco.com
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