draft-ietf-idr-bgp-extended-messages-27.txt   draft-ietf-idr-bgp-extended-messages-28.txt 
Network Working Group R. Bush Network Working Group R. Bush
Internet-Draft Internet Initiative Japan Internet-Draft Internet Initiative Japan
Updates: 4271 (if approved) K. Patel Updates: 4271 (if approved) K. Patel
Intended status: Standards Track Arrcus, Inc. Intended status: Standards Track Arrcus, Inc.
Expires: June 5, 2019 D. Ward Expires: August 17, 2019 D. Ward
Cisco Systems Cisco Systems
December 2, 2018 February 13, 2019
Extended Message support for BGP Extended Message support for BGP
draft-ietf-idr-bgp-extended-messages-27 draft-ietf-idr-bgp-extended-messages-28
Abstract Abstract
The BGP specification mandates a maximum BGP message size of 4096 The BGP specification mandates a maximum BGP message size of 4096
octets. As BGP is extended to support newer AFI/SAFIs and other octets. As BGP is extended to support newer AFI/SAFIs and other
features, there is a need to extend the maximum message size beyond features, there is a need to extend the maximum message size beyond
4096 octets. This document updates the BGP specification RFC4271 by 4096 octets. This document updates the BGP specification RFC4271 by
providing an extension to BGP to extend its current maximum message providing an extension to BGP to extend its current maximum message
size from 4096 octets to 65535 octets for all except the OPEN size from 4096 octets to 65535 octets for all except the OPEN
message. message.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 5, 2019. This Internet-Draft will expire on August 17, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BGP Extended Message . . . . . . . . . . . . . . . . . . . . 2 2. BGP Extended Message . . . . . . . . . . . . . . . . . . . . 2
3. Extended Message Capability for BGP . . . . . . . . . . . . . 3 3. Extended Message Capability for BGP . . . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 4 5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 4
6. Changes to RFC4271 . . . . . . . . . . . . . . . . . . . . . 4 6. Changes to RFC4271 . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Security Considerations . . . . . . . . . . . . . . . . . . . 4 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5 10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 5 10.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
The BGP specification [RFC4271] mandates a maximum BGP message size The BGP specification [RFC4271] mandates a maximum BGP message size
of 4096 octets. As BGP is extended to support newer AFI/SAFIs and of 4096 octets. As BGP is extended to support newer AFI/SAFIs and
newer capabilities (e.g., [I-D.ietf-sidr-bgpsec-protocol]), there is newer capabilities (e.g., BGPsec, [RFC8205], BGP-LS, [RFC7752]),
a need to extend the maximum message size beyond 4096 octets. This there is a need to extend the maximum message size beyond 4096
draft provides an extension to BGP to extend its current message size octets. This draft provides an extension to BGP to extend its
limit from 4096 octets to 65535 octets for all except the OPEN current message size limit from 4096 octets to 65535 octets for all
message. except the OPEN message.
2. BGP Extended Message 2. BGP Extended Message
A BGP message over 4096 octets in length is a 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 BGP Extended Messages have maximum message size of 65535 octets. The
smallest message that may be sent consists of a BGP header without a smallest message that may be sent consists of a BGP header without a
data portion (19 octets). data portion (19 octets).
3. Extended Message Capability for BGP 3. Extended Message Capability for BGP
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Extended Messages, and BGP Extended Messages MUST NOT be sent to it. Extended Messages, and BGP Extended Messages MUST NOT be sent to it.
The BGP Extended Message Capability is a new BGP Capability [RFC5492] The BGP Extended Message Capability is a new BGP Capability [RFC5492]
defined with Capability code 6 and Capability length 0. defined with Capability code 6 and Capability length 0.
4. Operation 4. Operation
A BGP speaker that is capable of sending and receiving BGP Extended A BGP speaker that is capable of sending and receiving BGP Extended
Messages SHOULD advertise the BGP Extended Message Capability to the Messages SHOULD advertise the BGP Extended Message Capability to the
peer using BGP Capabilities Advertisement [RFC5492]. A BGP speaker peer using BGP Capabilities Advertisement [RFC5492]. A BGP speaker
MAY send Extended Messages to its peer only if it has received the MAY send Extended Messages to its peer only if it has sent and
Extended Message Capability from that peer. received the Extended Message Capability from that peer.
The Extended Message Capability only applies to all messages except The Extended Message Capability applies to all messages except for
for the OPEN message. This exception is made to reduce compexity of the OPEN message. This exception is made to reduce complexity of
providing backward compatibility providing backward compatibility
An implementation that advertises support for BGP Extended Messages An implementation that advertises support for BGP Extended Messages
MUST be capable of receiving a message with a length up to and MUST be capable of receiving a message with a length up to and
including 65535 octets. including 65535 octets.
Applications generating information which might be encapsulated Applications generating information which might be encapsulated
within BGP messages MUST limit the size of their payload to take the within BGP messages MUST limit the size of their payload to take the
maximum message size into account. maximum message size into account.
If a BGP update with a payload longer than 4096 octets is received by
a BGP listener who has neither advertised nor agreed to accept BGP
Extended Messages, the listener MUST treat this as a malformed update
message, and MUST raise an UPDATE Message Error (see [RFC4271] Sec
6.3).
A BGP announcement will, in the normal case, propagate throughout the A BGP announcement will, in the normal case, propagate throughout the
BGP speaking Internet; and there will undoubtedly be BGP speakers BGP speaking Internet; and there will undoubtedly be BGP speakers
which do not have the Extended Message capability. Therefore, which do not have the Extended Message capability. Therefore,
putting an attribute which can not be decomposed to 4096 octets or putting an attribute which can not be decomposed to 4096 octets or
less in an Extended Message is a likely path to routing failure. less in an Extended Message is a likely path to routing failure.
It is RECOMMENDED that BGP protocol developers and implementers are It is RECOMMENDED that BGP protocol developers and implementers are
conservative in their application and use of Extended Messages. conservative in their application and use of Extended Messages.
Future protocol specifications will need to describe how to handle Future protocol specifications will need to describe how to handle
peers which can only accommodate 4096 octet messages. peers which can only accommodate 4096 octet messages.
5. Error Handling 5. Error Handling
A BGP speaker that has the ability to use Extended Messages but has A BGP speaker that has the ability to use Extended Messages but has
not advertised the BGP Extended Messages capability, presumably due not advertised the BGP Extended Messages capability, presumably due
to configuration, SHOULD NOT accept an Extended Message. A speaker to configuration, SHOULD NOT accept an Extended Message. A speaker
MAY implement a more liberal policy and accept Extended Messages, MAY implement a more liberal policy and accept Extended Messages,
even from a peer to which it has not advertised the capability, in even from a peer to which it has not advertised the capability, in
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[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006, RFC 4272, DOI 10.17487/RFC4272, January 2006,
<http://www.rfc-editor.org/info/rfc4272>. <http://www.rfc-editor.org/info/rfc4272>.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement [RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <http://www.rfc-editor.org/info/rfc5492>. 2009, <http://www.rfc-editor.org/info/rfc5492>.
10.2. Informative References 10.2. Informative References
[I-D.ietf-sidr-bgpsec-protocol] [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
Lepinski, M., "BGPSEC Protocol Specification", draft-ietf- S. Ray, "North-Bound Distribution of Link-State and
sidr-bgpsec-protocol-07 (work in progress), February 2013. Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<http://www.rfc-editor.org/info/rfc7752>.
[RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
Specification", RFC 8205, DOI 10.17487/RFC8205, September
2017, <https://www.rfc-editor.org/info/rfc8205>.
Authors' Addresses Authors' Addresses
Randy Bush Randy Bush
Internet Initiative Japan Internet Initiative Japan
5147 Crystal Springs 5147 Crystal Springs
Bainbridge Island, Washington 98110 Bainbridge Island, Washington 98110
United States of America United States of America
Email: randy@psg.com Email: randy@psg.com
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