wdiff rfc8092.original rfc8092.txt

IDR
Internet Engineering Task Force (IETF) J. Heitz, Ed.
Internet-Draft
Request for Comments: 8092 Cisco
Intended status:
Category: Standards Track J. Snijders, Ed.
Expires: July 9, 2017
ISSN: 2070-1721 NTT
K. Patel
Arrcus
I. Bagdonas
Equinix
N. Hilliard
INEX
January 5,
February 2017

BGP Large Communities
draft-ietf-idr-large-community-12 Attribute

Abstract

This document describes the BGP Large 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 with all Autonomous
System Numbers (ASNs) including four-octet Autonomous System Numbers.

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]. ASNs.

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 an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum 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 six months this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained 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 July 9, 2017.
http://www.rfc-editor.org/info/rfc8092.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 ....................................................2
2. Requirements Language ...........................................3
3. BGP Large Communities Attribute . . . . . . . . . . . . . . . 3
3. Aggregation . . . . . . . . . . . . . . . . . . . . . . . . . 4 .................................3
4. Aggregation .....................................................4
5. Canonical Representation . . . . . . . . . . . . . . . . . . 4
5. ........................................4
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 4
6. ..................................................5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION 5 .........................................5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 .............................................6
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. ......................................................6
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
11.2. .......................................6
9.2. Informative References . . . . . . . . . . . . . . . . . 7
11.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 8 .....................................6
Acknowledgments ....................................................7
Contributors .......................................................7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 .................................................8

1. Introduction

BGP [RFC4271] implementations typically support a routing policy
language to control the distribution of routing information. Network
operators attach BGP communities to routes to associate particular
properties with 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 is
applied to all routes contained in a BGP Update Message where the
Communities Attribute is included. 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.

A BGP Communities attributes are attribute is a variable length variable-length attribute consisting
of a set of one or more four-octet values, each of which specify a
community [RFC1997]. Common use of the individual values of this
attribute type split this single 32-bit value into two 16-bit values.
The most significant word is interpreted as an Autonomous System
Number (ASN) (ASN), and the least significant word is a locally defined
value whose meaning is assigned by the operator of the Autonomous
System AS 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. The six-octet length of the
Extended Community value precludes the common operational practise practice of
encoding four-octet ASNs in both the Global Administrator and the
Local Administrator sub-fields.

To address these shortcomings, this document defines a BGP Large
Communities attribute encoded as an unordered set of one or more
twelve-octet values, each consisting of a four-octet Global
Administrator field and two four-octet operator-defined fields, each
of which can be used to denote properties or actions significant to
the operator of the Autonomous System AS assigning the values.

2. 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].

3. BGP Large Communities Attribute

This document defines the BGP Large Communities attribute as an
optional transitive path attribute of variable length. All routes
with the BGP Large Communities attribute belong to the communities
specified in the attribute.

Each BGP Large Community value is encoded as a 12-octet quantity, 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.

Local Data Part 1: A four-octet operator-defined value.

Local Data Part 2: A four-octet operator-defined value.

The Global Administrator field is intended to allow different
Autonomous Systems ASes to
define BGP Large Communities without collision. This field SHOULD be
an Autonomous System Number (ASN), ASN, in which case the Local Data Parts are to be interpreted as
defined by the owner of the ASN. The use of Reserved ASNs (0
[RFC7607], 65535 and 4294967295 [RFC7300]) is NOT RECOMMENDED.

There is no significance to the order in which twelve-octet Large
Community Attribute values are encoded in a Large Communities
attribute, A BGP speaker can transmit them in any order.

Duplicate BGP Large Community values MUST NOT be transmitted. A
receiving speaker MUST silently remove redundant BGP Large Community
values from a BGP Large Community attribute.

4. Aggregation

If a range of routes is aggregated, then the resulting aggregate
should have a BGP Large Communities attribute which that contains all of
the BGP Large Communities attributes from all of the aggregated
routes.

5. Canonical Representation

The canonical representation of BGP Large Communities is three
separate unsigned integers in decimal notation in the following
order: Global Administrator, Local Data 1, Local Data 2. Numbers
MUST NOT contain leading zeros; a zero value MUST be represented with
a single zero. Each number is separated from the next by a single
colon. For example: 64496:4294967295:2, 64496:0:0.

BGP Large Communities SHOULD be represented in the canonical
representation.

6. Error Handling

The error handling of BGP Large Communities is as follows:

o A BGP Large Communities attribute SHALL be considered malformed if
the length of the BGP Large Communities Attribute value, expressed
in octets, is not a non-zero multiple of 12.

o A BGP Large Communities attribute SHALL NOT be considered
malformed due solely to presence of duplicate community Large Community values.

o A BGP UPDATE message with a malformed BGP Large Communities
attribute SHALL be handled using the approach of "treat-as-
withdraw" as described in section Section 2 of [RFC7606].

The BGP Large Communities Global Administrator field may contain any
value, and a BGP Large Communities attribute MUST NOT be considered
malformed if the Global Administrator field contains an unallocated,
unassigned
unassigned, or reserved ASN.

7. Security Considerations

This document does not change any underlying security issues
associated with any other BGP Communities mechanism. Specifically,
an AS relying on the BGP Large Communities attribute carried in BGP
must have trust in every other AS in the path, as any intermediate
Autonomous System AS
in the path may have added, deleted, or altered the BGP Large
Communities attribute. Specifying the mechanism to provide such
trust is beyond the scope of this document.

BGP Large Communities do not protect the integrity of each community
value. Operators should be aware that it is possible for a BGP
speaker to alter BGP Large Community Attribute values in a BGP Update
Message. Protecting the integrity of the transitive handling of BGP
Large Community attributes in a manner consistent with the intent of
expressed BGP routing policies falls within the broader scope of
securing BGP, and is not specifically addressed here.

Network administrators should note the recommendations in Section 11
of BGP "BGP Operations and Security Security" [RFC7454].

7. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION

This section records

8. IANA Considerations

IANA has assigned 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 BGP
Large Communities:

o Cisco IOS XR

o ExaBGP

o GoBGP

o BIRD

o OpenBGPD

o pmacct

o Quagga

The latest implementation news is tracked at
http://largebgpcommunities.net/ [1].

8. IANA Considerations

IANA has made an Early Allocation of the value 32 (LARGE_COMMUNITY)
in value 32 (LARGE_COMMUNITY) in the "BGP Path
Attributes" registry subregistry under the "Border Gateway Protocol (BGP)
Parameters" group and is now asked to make that
Permanent. registry.

9. Contributors

The following people contributed significantly to the content of the
document:

John Heasley
NTT Communications
Email: heas@shrubbery.net

Adam Simpson
Nokia
Email: adam.1.simpson@nokia.com

10. Acknowledgments

The authors would like to thank Ruediger Volk, Russ White, Acee
Lindem, Shyam Sethuram, Jared Mauch, Joel M. Halpern, Jeffrey Haas,
Gunter van de Velde, Marco Marzetti, Eduardo Ascenco Reis, Mark
Schouten, Paul Hoogsteder, Martijn Schmidt, Greg Hankins, 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, Remco
van Mook, Adam Chappell, Jussi Peltola, Kristian Larsson, Markus
Hauschild, Richard Steenbergen, David Freedman, Richard Hartmann,
Geoff Huston, Mach Chen, and Alvaro Retana for their support,
insightful review and comments.

11. References

11.1.

9.1. Normative References

[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>.

[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.

[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.

9.2. Informative 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>.

[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>.

[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>.

[RFC7300] Haas, J. and J. Mitchell, "Reservation of Last Autonomous
System (AS) Numbers", BCP 6, RFC 7300,
DOI 10.17487/RFC7300, July 2014,
<http://www.rfc-editor.org/info/rfc7300>.

[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>.

[RFC7607] Kumari, W., Bush, R., Schiller, H., and K. Patel,
"Codification of AS 0 Processing", RFC 7607,
DOI 10.17487/RFC7607, August 2015,
<http://www.rfc-editor.org/info/rfc7607>.

11.3. URIs

[1] http://largebgpcommunities.net

Acknowledgments

Contributors

The following people contributed significantly to the content of the
document:

John Heasley
NTT Communications
Email: heas@shrubbery.net

Adam Simpson
Nokia
Email: adam.1.simpson@nokia.com

Authors' Addresses

Jakob Heitz (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95054
USA
United States of America

Email: jheitz@cisco.com

Job Snijders (editor)
NTT Communications
Theodorus Majofskistraat 100
Amsterdam 1065 SZ
The Netherlands

Email: job@ntt.net

Keyur Patel
Arrcus, Inc Inc.

Email: keyur@arrcus.com

Ignas Bagdonas
Equinix
80 Cheapside
London EC2V 6EE
United Kingdom

Email: ibagdona.ietf@gmail.com

Nick Hilliard
INEX
4027 Kingswood Road
Dublin 24
IE
Ireland

Email: nick@inex.ie