Network Working Group Yakov Rekhter (Juniper Networks)
Internet Draft Srihari R. Sangli (Cisco Systems)
Expiration Date: September 2009 Daniel Tappan
Intended Status: Proposed Standard
Four-octet AS Specific BGP Extended Community
draft-ietf-l3vpn-as4octet-ext-community-03.txt
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Internet Draftdraft-ietf-l3vpn-as4octet-ext-community-03.txt March 2009
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Abstract
This document defines a new type of a BGP extended community - four-
octet AS specific extended community. This community allows to carry
4 octet autonomous system numbers.
Specification of Requirements
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 RFC 2119 [RFC2119].
1. Introduction
This document defines a new type of BGP extended community
([RFC4360]) - four-octet AS specific extended community. This type of
extended community is similar to the two-octet AS specific extended
community, except that it can carry a four octets autonomous system
number.
2. Four-octet AS specific extended community
This is an extended type with Type Field comprising of 2 octets and
Value Field comprising of 6 octets.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x02 or 0x42 | Sub-Type | Global Administrator :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Global Administrator (cont.) | Local Administrator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value of the high-order octet of this extended type is either
0x02 (for transitive communities) or 0x42 (for non-transitive commu-
nities). The low-order octet of this extended type is used to
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indicate sub-types.
The Value Field consists of two sub-fields:
Global Administrator sub-field: 4 octets
This sub-field contains a 4-octets Autonomous System number
assigned by IANA.
Local Administrator sub-field: 2 octets
The organization identified by Autonomous System number in the
Global Administrator sub-field, can encode any information in
this sub-field. The format and meaning of the value encoded in
this sub-field should be defined by the sub-type of the commu-
nity.
3. Considerations for two-octet Autonomous Systems
As per [RFC4893], a two-octet Autonomous System number can be con-
verted into a 4-octet Autonomous System number by setting the two
high-order octets of the 4-octet field to zero.
As a consequence, at least in principle an autonomous system that
uses a two-octet Autonomous System number could use either two-octet
or four-octet AS specific extended communities. This is undesirable,
as both communities would be treated as different, even if they had
the same Sub-Type and Local Administrator values.
Therefore, for backward compatibility with existing deployments, and
to avoid inconsistencies between two-octet and four-octet specific
extended communities, autonomous systems that use two-octet
Autonomous System numbers SHOULD use two-octet AS specific extended
communities rather than four-octet AS specific extended communities.
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4. IANA Considerations
This document defines a class of extended communities called four-
octet AS specific extended community for which the IANA is to create
and maintain a registry entitled Four-octet AS Specific Extended Com-
munity. All the communities in this class are of extended Types.
Future assignment are to be made using the "First Come First Served"
policy defined in [RFC5226]. The Type values for the transitive com-
munities of the four-octet AS specific extended community class are
0x0200-0x02ff, and for the non-transitive communities of that class
are 0x4200-0x42ff. Assignments consist of a name and the value.
This document makes the following assignments for the four-octet AS
specific extended community:
Name Type Value
---- ----------
four-octet AS specific Route Target 0x0202
four-octet AS specific Route Origin 0x0203
5. Security Considerations
All the security considerations for BGP Extended Communities apply
here.
6. Acknowledgements
Thanks to Bruno Decraene for his contributions to this document.
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5226] Narten, T., Alvestrand, H., "Guidelines for Writing an IANA
Considerations Section in RFCs", RFC5226, May 2008.
[RFC4360] Srihari R. Sangli, Daniel Tappan, Yakov Rekhter, "BGP
Extended Communities Attribute", RFC 4360, February 2006.
[RFC4893] Vohra, Q., Chen, E., "BGP Support for Four-octet AS Number
Space", RFC 4893, May 2007.
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8. Non-normative References
9. Author Information
Yakov Rekhter
Juniper Networks, Inc.
e-mail: yakov@juniper.net
Srihari R. Sangli
Cisco Systems, Inc.
e-mail: rsrihari@cisco.com
Dan Tappan
Boxborough MA
e-mail: Dan.Tappan@Gmail.com
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