IDR J. Heitz, Ed.
Internet-Draft Cisco
Intended status: Standards Track J. Snijders, Ed.
Expires: April 19, 2017 NTT
K. Patel
Arrcus
I. Bagdonas
Equinix
A. Simpson
Nokia
N. Hilliard
INEX
October 16, 2016
Large BGP Communities
draft-ietf-idr-large-community-03
Abstract
This document describes the Large BGP Communities attribute, an
extension to BGP-4. This attribute provides a mechanism to signal
opaque information within separate namespaces to aid in routing
management. The attribute is suitable for use in four-octet ASNs.
Requirements Language
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 [RFC2119].
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 April 19, 2017.
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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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Large BGP Communities Attribute . . . . . . . . . . . . . . . 3
3. Aggregation . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Canonical Representation . . . . . . . . . . . . . . . . . . 4
5. Reserved Large BGP Community values . . . . . . . . . . . . . 4
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION 5
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
11.1. Normative References . . . . . . . . . . . . . . . . . . 6
11.2. Informative References . . . . . . . . . . . . . . . . . 7
11.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
BGP implementations typically support a routing policy language to
control the distribution of routing information. Network operators
attach BGP communities to routes to identify intrinsic properties of
these routes. These properties may include information such as the
route origin location, or specification of a routing policy action to
be taken, or one that has been taken, and may apply to an individual
route or to a group of routes. Because BGP communities are optional
transitive BGP attributes, BGP communities may be acted upon or
otherwise used by routing policies in other Autonomous Systems (ASes)
on the Internet.
[RFC1997] BGP Communities attributes are four-octet values split into
two two-octet words. The most significant word is usually
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interpreted as an Autonomous System Number (ASN) and the least
significant word is a locally defined value whose meaning is assigned
by the operator of the Autonomous System in the most significant
word.
Since the adoption of four-octet ASNs [RFC6793], the BGP Communities
attribute can no longer accommodate the above encoding, as a two-
octet word cannot fit a four-octet ASN. The BGP Extended Communities
attribute [RFC4360] is also unsuitable, as the protocol limit of six
octets cannot accommodate both a four-octet Global Administrator
value and a four-octet Local Administrator value, which precludes the
common operational practice of encoding a target ASN in the Local
Administrator field.
To address these shortcomings, this document defines a Large BGP
Communities attribute encoded as one or more twelve-octet values,
each consisting of a four-octet ASN and two four-octet operator-
defined values, each of which can be used to denote properties or
actions significant to that ASN.
2. Large BGP Communities Attribute
This document creates the Large BGP Communities attribute as an
optional transitive path attribute of variable length. All routes
with the Large BGP Communities attribute belong to the community
specified in the attribute.
The attribute consists of one or more twelve-octet values. Each
twelve-octet Large BGP Communities value represents three four-octet
values, as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Administrator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Data Part 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Data Part 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Global Administrator: A four-octet namespace identifier. This
SHOULD be an Autonomous System Number.
Local Data Part 1: A four-octet operator-defined value.
Local Data Part 2: A four-octet operator-defined value.
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The Global Administrator field is intended to allow different
Autonomous Systems to define Large BGP Communities without collision.
Implementations MUST allow the operator to specify any value for the
Global Administrator field.
There is no significance to the order in which Large BGP Communities
are encoded in a path attributes field and a receiving speaker MAY
retransmit them in an order different from which it received them.
Duplicate Large BGP Communities SHOULD NOT be transmitted. A
receiving speaker SHOULD silently remove duplicate Large BGP
Communities from a BGP UPDATE message.
3. Aggregation
If a range of routes is aggregated, then the resulting aggregate
should have a Large BGP Communities attribute which contains all of
the Large BGP Communities attributes from all of the aggregated
routes.
4. Canonical Representation
Large BGP Communities MUST be represented as three separate unsigned
decimal numbers, without leading zeros, in the following order:
Global Administrator, Local Data 1, Local Data 2. Numbers MUST not
be omitted, even when zero. For example: 64496:4294967295:2 or
64496:0:0 or (64496, 111, 222).
5. Reserved Large BGP Community values
The Large BGP Community attribute values in the following ranges are
reserved:
0:0:0 - 0:4294967295:4294967295
65535:0:0 - 65535:4294967295:4294967295
4294967295:0:0 - 4294967295:4294967295:4294967295
6. Error Handling
The error handling of Large BGP Communities is as follows:
o A Large BGP Communities attribute with a length of zero MUST be
ignored upon receipt and removed when sending.
o A Large BGP Communities attribute SHALL be considered malformed if
its length is not a non-zero multiple of 12 bytes.
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o A BGP UPDATE message with a malformed Large BGP Communities
attribute SHALL be handled using the approach of "treat-as-
withdraw" as described in section 2 [RFC7606].
The Large BGP Communities Global Administrator field may contain any
value, and a Large BGP Communities attribute MUST NOT be considered
malformed if the Global Administrator field contains an unallocated,
unassigned or reserved ASN or is set to one of the reserved Large BGP
Community values defined in Section 5.
7. Security Considerations
This extension to BGP has similar security implications as BGP
Communities [RFC1997].
This document does not change any underlying security issues
associated with any other BGP Communities mechanism. Specifically,
an AS relying on the Large BGP Communities attribute carried in BGP
must have trust in every other AS in the path, as any intermediate
Autonomous System in the path may have added, deleted or altered the
Large BGP Communities attribute. Specifying the mechanism to provide
such trust is beyond the scope of this document.
Network administrators should note the recommendations in Section 11
of BGP Operations and Security [RFC7454].
8. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
As of today these vendors have produced an implementation of Large
BGP Communities:
o Cisco IOS XR
o ExaBGP
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o GoBGP
o BIRD
o OpenBGPD
o pmacct
The latest implementation news is tracked at
http://largebgpcommunities.net/ [1].
9. IANA Considerations
IANA has made an Early Allocation of the value 30 (LARGE_COMMUNITY)
in the "BGP Path Attributes" registry under the "Border Gateway
Protocol (BGP) Parameters" group and is now asked to make that
Permanent.
10. Acknowledgments
The authors would like to thank Ruediger Volk, Russ White, Acee
Lindem, Shyam Sethuram, Jared Mauch, Joel M. Halpern, Jeffrey Haas,
John Heasley, Gunter van de Velde, Marco Marzetti, Eduardo Ascenco
Reis, Mark Schouten, Paul Hoogsteder, Martijn Schmidt, Greg Hankins,
Acee Lindem, Bertrand Duvivier, Barry O'Donovan, Grzegorz Janoszka,
Linda Dunbar, Marco Davids, Gaurab Raj Upadhaya, Jeff Tantsura, Teun
Vink, Adam Davenport, Theodore Baschak, Pier Carlo Chiodi, Nabeel
Cocker, Ian Dickinson, Jan Baggen, Duncan Lockwood, David Farmer,
Randy Bush, Wim Henderickx, Stefan Plug, Kay Rechthien, Rob Shakir,
Warren Kumari, Gert Doering, Thomas King, Mikael Abrahamsson, Wesley
Steehouwer, Sander Steffann, Brad Dreisbach, Martin Millnert,
Christopher Morrow, Jay Borkenhagen, Arnold Nipper, Joe Provo, Niels
Bakker, Bill Fenner, Tom Daly, Ben Maddison, Alexander Azimov, Brian
Dickson, Peter van Dijk, Julian Seifert, Tom Petch, Tom Scholl, Arjen
Zonneveld, and Remco van Mook for their support, insightful review
and comments.
11. References
11.1. Normative References
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<http://www.rfc-editor.org/info/rfc1997>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793,
DOI 10.17487/RFC6793, December 2012,
<http://www.rfc-editor.org/info/rfc6793>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<http://www.rfc-editor.org/info/rfc7606>.
11.2. Informative References
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <http://www.rfc-editor.org/info/rfc4360>.
[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
February 2015, <http://www.rfc-editor.org/info/rfc7454>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<http://www.rfc-editor.org/info/rfc7942>.
11.3. URIs
[1] http://largebgpcommunities.net
Authors' Addresses
Jakob Heitz (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95054
USA
Email: jheitz@cisco.com
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Job Snijders (editor)
NTT Communications
Theodorus Majofskistraat 100
Amsterdam 1065 SZ
NL
Email: job@ntt.net
Keyur Patel
Arrcus, Inc
Email: keyur@arrcus.com
Ignas Bagdonas
Equinix
London
UK
Email: ibagdona.ietf@gmail.com
Adam Simpson
Nokia
600 March Road
Ottawa Ontario K2K 2E6
Canada
Email: adam.1.simpson@nokia.com
Nick Hilliard
INEX
4027 Kingswood Road
Dublin 24
IE
Email: nick@inex.ie
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