draft-ietf-idr-bgp-extended-messages-21.txt   draft-ietf-idr-bgp-extended-messages-22.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: September 6, 2017 D. Ward Expires: February 16, 2018 D. Ward
Cisco Systems Cisco Systems
March 5, 2017 August 15, 2017
Extended Message support for BGP Extended Message support for BGP
draft-ietf-idr-bgp-extended-messages-21 draft-ietf-idr-bgp-extended-messages-22
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, there is a octets. As BGP is extended to support newer AFI/SAFIs and other
need to extend the maximum message size beyond 4096 octets. This features, there is a need to extend the maximum message size beyond
document updates the BGP specification RFC4271 by providing an 4096 octets. This document updates the BGP specification RFC4271 by
extension to BGP to extend its current maximum message size from 4096 providing an extension to BGP to extend its current maximum message
octets to 65535 octets. size from 4096 octets to 65535 octets for all except the OPEN
message.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
be interpreted as described in [RFC2119] only when they appear in all be interpreted as described in [RFC2119] only when they appear in all
upper case. They may also appear in lower or mixed case as English upper case. They may also appear in lower or mixed case as English
words, without normative meaning. words, without normative meaning.
Status of This Memo Status of This Memo
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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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 September 6, 2017. This Internet-Draft will expire on February 16, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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10.2. Informative References . . . . . . . . . . . . . . . . . 5 10.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
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., [I-D.ietf-sidr-bgpsec-protocol]), there is
a need to extend the maximum message size beyond 4096 octets. This a need to extend the maximum message size beyond 4096 octets. This
draft provides an extension to BGP to extend its current message size draft provides an extension to BGP to extend its current message size
limit from 4096 octets to 65535 octets. limit from 4096 octets to 65535 octetsfor all 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).
Multi-octet fields MUST be in network byte order. Multi-octet fields MUST be in network byte order.
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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 willing to send and receive BGP Extended A BGP speaker that is willing to send and receive BGP Extended
Messages with a peer SHOULD advertise the BGP Extended Message Messages with a peer SHOULD advertise the BGP Extended Message
Capability to the peer using BGP Capabilities Advertisement Capability to the peer using BGP Capabilities Advertisement
[RFC5492]. A BGP speaker MAY send Extended Messages to its peer only [RFC5492]. A BGP speaker MAY send Extended Messages to its peer only
if it has received the Extended Message Capability from that peer. if it has received the Extended Message Capability from that peer.
Currently, the Extended Message Capability only applies to UPDATE The Extended Message Capability only applies to all messages except
messages. for the OPEN message. This exception is reduce compexity of
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 an UPDATE message with a length up to MUST be capable of receiving a message with a length up to and
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.
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 putting which do not have the Extended Message capability. Therefore putting
an attribute which can not be decomposed to 4096 octets or less in an an attribute which can not be decomposed to 4096 octets or less in an
Extended Message is a sure path to routing failure. Extended Message is a likely path to routing failure.
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
the interest of preserving the BGP session if at all possible. the interest of preserving the BGP session if at all possible.
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The inconsistency between the local and remote BGP speakers MUST be The inconsistency between the local and remote BGP speakers MUST be
flagged to the network operator through standard operational flagged to the network operator through standard operational
interfaces. The information should include the NLRI and as much interfaces. The information should include the NLRI and as much
relevant information as reasonably possible. relevant information as reasonably possible.
6. Changes to RFC4271 6. Changes to RFC4271
[RFC4271] states "The value of the Length field MUST always be at [RFC4271] states "The value of the Length field MUST always be at
least 19 and no greater than 4096." This document changes the latter least 19 and no greater than 4096." This document changes the latter
number to 65535 for UPDATE messages. number to 65535 for all except the OPEN message.
[RFC4271] Sec 6.1, specifies raising an error if the length of a [RFC4271] Sec 6.1, specifies raising an error if the length of a
message is over 4096 octets. For UPDATE messages, if the receiver message is over 4096 octets. For all messages except the OPEN
has advertised the capability to receive Extended Messages, this message, if the receiver has advertised the capability to receive
document raises that limit to 65535. Extended Messages, this document raises that limit to 65535.
7. IANA Considerations 7. IANA Considerations
The IANA has made an early allocation for this new BGP BGP Extended The IANA has made an early allocation for this new BGP BGP Extended
Message Capability referring to this document. Message Capability referring to this document.
Registry: BGP Capability Code Registry: BGP Capability Code
Value Description Document Value Description Document
----- ----------------------------------- ------------- ----- ----------------------------------- -------------
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The authors thank Alvaro Retana, Enke Chen, Susan Hares, John The authors thank Alvaro Retana, Enke Chen, Susan Hares, John
Scudder, John Levine, and Job Snijders for their input; and Oliver Scudder, John Levine, and Job Snijders for their input; and Oliver
Borchert and Kyehwan Lee for their implementations and testing. Borchert and Kyehwan Lee for their implementations and testing.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Protocol 4 (BGP-4)", RFC 4271, January 2006. Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, January 2006. RFC 4272, DOI 10.17487/RFC4272, January 2006,
<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, February 2009. with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <http://www.rfc-editor.org/info/rfc5492>.
10.2. Informative References 10.2. Informative References
[I-D.ietf-sidr-bgpsec-protocol] [I-D.ietf-sidr-bgpsec-protocol]
Lepinski, M., "BGPSEC Protocol Specification", draft-ietf- Lepinski, M., "BGPSEC Protocol Specification", draft-ietf-
sidr-bgpsec-protocol-07 (work in progress), February 2013. sidr-bgpsec-protocol-07 (work in progress), February 2013.
Authors' Addresses Authors' Addresses
Randy Bush Randy Bush
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