IDR Working Group R. Raszuk
Internet-Draft Cisco Systems
Intended status: Standards Track J. Haas
Expires: April 19, 2011 Juniper Networks
October 16, 2010
Registered Wide BGP Community Values
draft-raszuk-registered-wide-bgp-community-values-00
Abstract
Communicating various routing policies via route tagging plays an
important role in external BGP peering relations. The most common
tool used today to attach various information about routes is
realized with the use of BGP communities. Such information is
important for the peering AS to perform some mutually agreed actions
without the need to maintain a separate offline database for each
pair of prefix and an associated with it requested set of action
entries.
This document proposes to establish a new IANA maintained registry of
most commonly used Wide BGP Communities by network operators. Such
public registry will allow for easy refernece and clear
interpretation of the actions associated with received community
values.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 19, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Globally significant pre-defined values . . . . . . . . . . . 3
2.1. Well Known Standard BGP Communities . . . . . . . . . . . 3
2.2. Registered pre-defined Wide BGP Communities . . . . . . . 3
2.2.1. General Registered Wide BGP Community Values . . . . . 4
2.2.2. Advertisement control Registered Wide BGP
Communities . . . . . . . . . . . . . . . . . . . . . 7
2.2.3. AS source marking Registered Wide BGP Communities . . 8
2.2.4. Return path influencing Registered Wide BGP
Communities . . . . . . . . . . . . . . . . . . . . . 10
2.2.5. AS_PATH modifying Registered Wide BGP Communities . . 10
2.2.6. Local Preference Registered Community . . . . . . . . 11
2.2.7. AS_PATH TTL Registered Community . . . . . . . . . . . 12
3. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4. Security considerations . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Normative References . . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
RFC 1997 [RFC1997] defines a BGP Community Attribute to be used as a
tool to contain in BGP update message various additional information
about routes which may help to automate peering administration. As
defined in RFC 1997 [RFC1997] BGP Communities attribute consists of
one or more sets of four octet values, where each one of them
specifies a different community. Except two reserved ranges the
encoding of community values mandates that first two octets are to
contain the Autonomous System number followed by next two octets
containing locally defined value.
This document lists the most commonly used today BGP communities as
well as provides a new registry for future definitions.
2. Globally significant pre-defined values
2.1. Well Known Standard BGP Communities
According to RFC 1997 as well as to IANA's Well-Known BGP Communities
registry today the following BGP communities are defined to have
global significance:
+------------+---------------------+----------------------------+
| 0xFFFF0000 | planned-shut | [draft-francois-bgp-gshut] |
| 0xFFFFFF01 | NO_EXPORT | [RFC1997] |
| 0xFFFFFF02 | NO_ADVERTISE | [RFC1997] |
| 0xFFFFFF03 | NO_EXPORT_SUBCONFED | [RFC1997] |
| 0xFFFFFF04 | NOPEER | [RFC3765] |
+------------+---------------------+----------------------------+
This document recommends for simplicity as well as for avoidance of
backward compatibility issues the continued use of BGP Standard
Community Attribute type 8 as defined in RFC 1997 to distribute non
Autonomous System specific Well-Known BGP Communities.
For the same reason the described registry does not intend to
obsolete BGP Extended Community Attribute and any already defined and
deployed extended communities. The new registry is to be used
primarly for new community definitions in particular those which
require to carry various new parameters or which should be propagated
with a controled scope and radius.
2.2. Registered pre-defined Wide BGP Communities
It has been requested numerous times to have a globally unified way
to express some particular Autonomous System based routing policies.
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When defining a new way to encode bgp communities we have an
opportunity to define set of new registered routing policies and
route markings which could be passed within and between Autonomous
Systems resulting in their common interpretation.
This document will request IANA to define and maintain a new registry
for pre-defined Wide BGP Community values. The allocation policy is
on a first come first served basis.
It is recommended that an implementation supports by an explicit
enabling defined below Registered Wide BGP Communities. Depending on
the BGP implementation support it is recommended that an
implementation would support Registered Wide BGP Communities without
breaking static or dynamic peer/update groups. However it needs to
be pointed out that support of all Registered Wide BGP Communities is
not mandatory. It will be perfectly valid for any BGP implementation
to support only subset of Wide BGP Communities.
It is strongly advised that each Autonomous System does an inbound
verification of received Wide BGP Communities from all of its EBGP
peers before accepting them and propagating within their own domain.
The document does not mandate nor enforces that given registered type
value of Wide BGP Community would be of transitive or non-transitive
type. It is for the operator to determine the propagation AS radius
required for such community when appending it to routing information.
However the document will provide a transitivity radius
recommendation to defined communities.
The following Wide BGP Communities have global significance and their
execution should be uniformly implemented by any BGP speaker
supporting given set of Wide BGP Communities.
The defined below value of the community should be interpreted as
registered value only if "R" - registered bit is set in the community
Type 1 container as described in [draft-raszuk-wide-bgp-communities]
Otherwise the value is local and it's actions is locally defined by
the operator.
2.2.1. General Registered Wide BGP Community Values
The below set of communities will be defined to be carried in Wide
BGP Community Type 1, with the container type values as per
Section 5.
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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
+-+-+-+-+-+-+-+-+
| 0x01 |
+-+-+-+-+-+-+-+-+
|R C 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source AS number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Registered/Local value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter/s (optional, variable)... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Wide BGP Community Type 1
Description format:
NAME
TTL - defines domain or sub-domain propagation radius
LENGTH - Length of the TLV in octets
PARAMETERS - optional parameters for execution
DESCRIPTION - defines the use and post execution action
BLACKHOLE
TTL - Operator's defined
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - All transit traffic to destinations for which
advertised routes carry such community value should be dropped. It
is recommended that specified Autonomous System number should be
eligible and verified by BGP Origin Validation functionality to
advertise given BGP destinations.
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SOURCE BLACKHOLE
TTL - Operator's defined
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - All transit traffic which source addresses have been
tagged by such Wide BGP Community should be dropped.
SOURCE DO RPF
TTL - Operator's defined
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - All transit traffic which source addresses have been
tagged by such Wide BGP Community should be subject to Reverse Path
Forwarding check when crossing Autonomous System boundaries. Source
Autonomous System number specified in the body of this community
should directly indicate the peering interfaces on which such RPF
check should be performed.
HIGH PRIORITY PREFIX
TTL - 0x00 (local to domain)
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - BGP prefixes carrying such Wide BGP Community should be
advertised to restarting peers before other prefixes received by
given BGP speaker.
ATTACK TARGET
TTL - Operator's defined
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - The ATTACK_TARGET Registered Wide BGP Community
indicates that BGP prefixes carrying such community are receiving
unusual amount of unwanted traffic most likely due to some form of
network attack. Network devices capable of analyzing and mitigating
such attacks can use such community as a hint on what destinations to
focus the most.
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2.2.2. Advertisement control Registered Wide BGP Communities
NO ADVERTISE TO AS
TTL - Operator's defined
LENGTH - 17 octets
PARAMETERS - Target AS number - 4 octets
DESCRIPTION - All routes received which carry such Wide BGP Community
containing this value MUST NOT be advertised to BGP peer which
Autonomous System number has been listed in the body of this
community.
Semantically specifying the reserved Autonomous System value of
0xFFFFFFFF (ANY AS) would be an equivalent of using NO_ADVERTISE
Well-Known Standard BGP Community Attribute.
ADVERTISE TO AS
TTL - Operator's defined
LENGTH - 17 octets
PARAMETERS - Target AS number - 4 octets
DESCRIPTION - All routes received carrying such Wide BGP Community
containing this value MUST ONLY be advertised to BGP peers which
Autonomous System number is specified in the PARAMETER field of this
community.
Semantically specifying the reserved Autonomous System value of
0xFFFFFFFF (ANY AS) would be an equivalent of advertisement to all
neighbors. Post execution this community MUST be removed.
ADVERTISE AND SET NO EXPORT
TTL - Operator's defined
LENGTH - 17 octets
PARAMETERS - Target AS number - 4 octets
DESCRIPTION - All routes received carrying such Wide BGP Community
containing this value MUST be advertised to BGP peer which Autonomous
System number is specified in the PARAMETER section of this community
with NO_EXPORT Standard BGP Community attached.
Semantically specifying the reserved Autonomous System value of
0xFFFFFFFF (ANY AS) would be an equivalent of advertisement to all
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neighbors with NO_EXPORT community being set. Post execution this
community MUST be removed.
2.2.3. AS source marking Registered Wide BGP Communities
FROM PEER
TTL - 0x00 - Local AS tagging only
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - Autonomous System may attach this community to routes
received from their EBGP peers to later, when advertising them
outside the domain, apply or relax local policies only on such group
of destinations.
FROM CUSTOMER
TTL - 0x00 - Local AS tagging only
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - Autonomous System may attach this community to routes
received from their customers to later, when advertising them outside
the domain, apply or relax local policies only on such group of
destinations.
INTERNAL
TTL - 0x00 - Local AS tagging only
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - Autonomous System may attach this community to routes
originated in their own domain to later, when advertising them
outside the domain, apply or relax local policies only on such group
of destinations.
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FROM UPSTREAM
TTL - 0x00 - Local AS tagging only
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - Autonomous System may attach this community to routes
received from their EBGP upstream peers to later, when advertising
them outside the domain, apply or relax local policies only on such
group of destinations.
FROM IX
TTL - 0x00 Local AS tagging only
LENGTH - 13 octets
PARAMETERS - none
DESCRIPTION - Autonomous System may attach this community to routes
received from their EBGP peering sessions with the Internet Exchange
peers or with Route Server to later, when advertising them outside
the domain, apply or relax local policies only on such group of
destinations.
LEARNED FROM AS
TTL - 0x00 Local AS tagging only
LENGTH - 17 octets
PARAMETERS - 4 octets - Peer's AS number
DESCRIPTION - Autonomous System may attach this community to routes
received from their EBGP peer by explicitly tagging them with their
peer's Autonomous System number as a value of the PARAMETER field.
If the AS number is a two octet number first two octest will be
filled with zero. It is possible to use this to also carry private
AS number of customers.
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2.2.4. Return path influencing Registered Wide BGP Communities
PATH HINT
TTL - Operator's defined
LENGTH - 17 octets
PARAMETERS - 4 octets AS number
DESCRIPTION - Autonomous System receiving such Wide BGP Community
value should prefer for BGP prefixes received with such community
(for example by increasing value of local preference on ingress), a
BGP path which traverses Autonomous System number which has been
specified in the PARAMETER field of this community. Post execution
this community SHOULD be kept.
NEGATIVE PATH HINT
TTL - Operator's defined
LENGTH - 17 octets
PARAMETERS - 4 octets AS number
DESCRIPTION - Autonomous System receiving such Wide BGP Community
value should prefer for BGP prefixes received with such community
(for example by increasing value of local preference on ingress), a
BGP path which DOES NOT traverses Autonomous System number which has
been specified in the PARAMETERS field of this community. Post
execution this community SHOULD be kept.
2.2.5. AS_PATH modifying Registered Wide BGP Communities
PREPEND N TIMES BY AS
TTL - Operator's defined
LENGTH - 18 octets
PARAMETERS - 4 octets AS number + 1 octet prepend's number
DESCRIPTION - The Autonomous System specified in the PARAMETERS field
of such community should prepend N times its own Autonomous System
number when advertising routes tagged with this community to peers.
Number of requested AS prepends is provided in the last octet of
PARAMETERS field value. Post execution this community MUST be
removed.
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PREPEND N TIMES TO AS
TTL - Operator's defined
LENGTH - 18 octets
PARAMETERS - 4 octets AS number + 1 octet prepend's number
DESCRIPTION - The Autonomous System advertising routes externally
should prepend N times its own Autonomous System number when
advertising routes tagged with this community to peer which AS number
is defined by the first 4 octets of PARAMETERS field. Number of
requested AS prepends is provided in the last octet of PARAMETERS
field value. Post execution this community MUST be removed.
REPLACE BY
TTL - Operator's defined
LENGTH - 17 octets
PARAMETERS - 4 octets AS number
DESCRIPTION - All routes marked with such community advertised by an
Autonomous System to all of its external peers should have any
occurrence of an Autonomous System number specified in the PARAMETERS
field replaced with advertising domain's local Autonomous System
number. Post execution this community MUST be removed.
2.2.6. Local Preference Registered Community
LOCAL PREFERENCE
TTL - Operator's defined
LENGTH - 14 octets
PARAMETERS - 1 octet 1st bit indicates:
0-increment, 1-decrement;
7 bits - value of local preference value 1..127
DESCRIPTION - Autonomous System may suggest to its EBGP neighbor the
following adjustments to the value of local preference as specified
by given domain's local policy. The values of requested increment or
decrement local preference value is carried in the PARAMETERS field.
Post execution this community MUST be removed.
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2.2.7. AS_PATH TTL Registered Community
AS_PATH TTL MAX RADIUS
TTL - Operator's defined
LENGTH - 14 octets
PARAMETERS - 1 octet - max AS_PATH radius
DESCRIPTION - Autonomous System may suggest to drop advertised prefix
by any transit network if its AS_PATH attribute length would be equal
or greater to encoded value both inbound or outbound of EBGP session.
The value of max AS_PATH length allowed is specified in the
PARAMETERS field of the community. Post comparison this community
MUST be kept.
3. Example
Customer of the source AS number XYZ requests to execute AS_PATH
prepend 4 times when advertising the prefixes to AS number 2424. We
will use the following community assigned on ingress or at the prefix
origination.
PREPEND N TIMES TO AS
TTL - 0x00
LENGTH - 18 octets
VALUE - 17 / 0x12
PARAMETERS - 4 octets AS number + 1 octet prepend's number
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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
+-+-+-+-+-+-+-+-+
| 0x1 |
+-+-+-+-+-+-+-+-+
|1 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length: 18 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL: 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Own ASN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Community: PREPEND N TIMES TO AS / 0x12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target ASN / 0x0978 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prepend #: 4 |
+-+-+-+-+-+-+-+-+
4. Security considerations
All the security considerations for BGP Communities as well as for
BGP Extended Communities RFCs apply here.
5. IANA Considerations
This document requests IANA to define and maintain a new registry
named: "Registered Wide BGP Communities Values". The reserved pool
of 0x00000000-0xFFFFFFFF has been defined for its allocations. The
allocation policy is on a first come first served basis.
This document makes the following assignments for the Registered Wide
BGP Community values:
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+-----------------------------+------------+
| Name | Type Value |
+-----------------------------+------------+
| BLACKHOLE | 1 |
| SOURCE BLACKHOLE | 2 |
| SOURCE DO RPF | 3 |
| HIGH PRIORITY PREFIX | 4 |
| ATTACK TARGET | 5 |
| NO ADVERTISE TO AS | 6 |
| ADVERTISE TO AS | 7 |
| ADVERTISE AND SET NO EXPORT | 8 |
| FROM PEER | 9 |
| FROM CUSTOMER | 10 |
| INTERNAL | 11 |
| FROM UPSTREAM | 12 |
| FROM IX | 13 |
| LEARNED FROM AS | 14 |
| PATH HINT | 15 |
| PATH NEGATIVE HINT | 16 |
| PREPEND N TIMES BY AS | 17 |
| PREPEND N TIMES TO AS | 18 |
| REPLACE BY | 19 |
| LOCAL PREFERENCE | 20 |
| AS_PATH TTL MAX RADIUS | 21 |
| FREE POOL | 22.. |
+-----------------------------+------------+
6. Contributors
The following people contributed significantly to the content of the
document:
Bruno Decraene
France Telecom
38-40 rue du General Leclerc
92794 Issi Moulineaux cedex 9
France
Email: bruno.decraene@orange-ftgroup.com
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Shintaro Kojima
OTEMACHI 1st. SQUARE EAST TOWER, 3F
1-5-1, Otemachi,
Chiyoda-ku, Tokyo 100-0004
Japan
Email: koji@mfeed.ad.jp
Juan Alcaide
Cisco Systems
Research Triangle Park, NC
United States
Email: jalcaide@cisco.com
Burjiz Pithawala
Cisco Systems
170 West Tasman Dr
San Jose, CA
United States
Email: bpithaw@cisco.com
Saku Ytti
TDC Oy
Mechelininkatu 1a
00094 TDC
Finland
Email: ytti@tdc.net
Paul Jakma
School of Computing Science, Uni. of Glasgow
Sir Alwyn Williams Building
University of Glasgow
Glasgow
G1 5AE
UK
Email: paulj@dcs.gla.ac.uk
7. Acknowledgments
Authors would like to thank Enke Chen, Pedro Marques and Alton Lo for
their valuable input.
8. References
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8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
8.2. Informative References
[RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP
Communities Attribute", RFC 1997, August 1996.
[RFC1998] Chen, E. and T. Bates, "An Application of the BGP
Community Attribute in Multi-home Routing", RFC 1998,
August 1996.
[RFC4384] Meyer, D., "BGP Communities for Data Collection", BCP 114,
RFC 4384, February 2006.
[RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
Number Space", RFC 4893, May 2007.
[RFC5668] Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
Specific BGP Extended Community", RFC 5668, October 2009.
Authors' Addresses
Robert Raszuk
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
US
Email: raszuk@cisco.com
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Jeffrey Haas
Juniper Networks
1194 N.Mathilda Ave
Sunnyvale, CA 94089
US
Email: jhaas@pfrc.org
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