Network Working Group D. Rao Internet-Draft P. Mohapatra Intended status: Standards Track Cisco Systems Expires: April 24, 2009 J. Haas Arbor Networks October 21, 2008 Generic Subtype for BGP Four-octet AS specific extended community draft-dhrao-idr-4octet-extcomm-generic-subtype-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 24, 2009. Abstract Maintaining the current best practices with communities, ISPs and enterprises that get assigned a 4-octet AS number may want the BGP UPDATE messages they receive from their customers or peers to include a 4-octet AS specific extended community. This document defines a new sub-type within the four-octet AS specific extended community to facilitate this practice. Rao, et al. Expires April 24, 2009 [Page 1] Internet-Draft 4octet Extcomm generic sub-type October 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 2. Generic Subtype Definition . . . . . . . . . . . . . . . . . . 3 3. Deployment Considerations . . . . . . . . . . . . . . . . . . . 4 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Normative References . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Rao, et al. Expires April 24, 2009 [Page 2] Internet-Draft 4octet Extcomm generic sub-type October 2008 1. Introduction Maintaining the current best practices with communities, ISPs and enterprises that get assigned a 4-octet AS number may want the BGP UPDATE messages they receive from their customers or peers to include a 4-octet AS specific extended community. This document defines a new sub-type within the four-octet AS specific extended community to facilitate this practice. As an example, [RFC1998] describes an application of BGP community attribute ([RFC1997]) to implement flexible routing policies for sites multi-homed to one or multiple providers. In a two-octet AS environment, the advertised routes are usually associated with a community attribute that encodes the provider's AS number in the first two octets of the community and a LOCAL_PREF value in the second two octets of the community. The community attribute signals the provider edge routers connected to the site to set the corresponding LOCAL_PREF on their advertisements to the IBGP mesh. In this way, customers can put into practice topologies like active- backup. When such a provider is assigned a four-octet AS number, the existing mechanism of using communities is not sufficient since the community value can not exceed four bytes. The natural alternative is to extend the same mechanism using extended communities since it allows for encoding eight bytes of information. [I-D.ietf-l3vpn-as4octet-ext-community] defines four-octet AS specific extended community with a designated type field. At the time of writing this document, there are two known sub-types defined: Four-octet specific Route Target extended community and Four-octet specific Route Origin extended community. This document specifies a generic sub-type for the four-octet AS specific extended community to provide benefits such as the one cited above as the Internet migrates to four-octet AS space. 1.1. 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 RFC 2119 [RFC2119]. 2. Generic Subtype Definition Rao, et al. Expires April 24, 2009 [Page 3] Internet-Draft 4octet Extcomm generic sub-type October 2008 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 | 0x04 | Four-Octet AS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Four-Octet AS (cont.) | Local Administrator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This is a transitive extended community with Type Field comprising of 2 octets and Value Field comprising of 6 octets. The high-order octet of this extended type is set to 0x02 as defined in [I-D.ietf-l3vpn-as4octet-ext-community]. The low-order octet or the sub-type is set to 0x04. The Value Field consists of two sub-fields: Global Administrator sub-field: 4 octets This sub-field contains a four-octet Autonomous System number. Local Administrator sub-field: 2 octets This sub-field contains a value that can influence routing policies. It is expected that the values will be identical to the ones used in practice with standard communities and will be of significance between the local Autonomous System and its customer or peering Autonomous Systems. 3. Deployment Considerations A speaker with a 4-octet Autonomous System may have a customer or peer with a 2-octet Autonomous System. If such a peer supports 4-octet extended communities, then it will be able to tag its routes with the 4-octet extended community defined by the speaker. If the peer does not support 4-octet extended communities, then the speaker may need to define an appropriate standard community value for the same purpose. Similarly, a 2-octet AS may have two valid representations as either a standard community or a 4-octet extended community with the upper two octets of the AS set to zero. Therefore, as per [I-D.ietf-l3vpn-as4octet-ext-community], two-octet ASes SHOULD use standard 2-octet communities rather than 4-octet AS specific extended communities in order to avoid inconsistencies. Rao, et al. Expires April 24, 2009 [Page 4] Internet-Draft 4octet Extcomm generic sub-type October 2008 4. Acknowledgments 5. IANA Considerations IANA is requested to assign sub-type 0x04 as a generic four-octet AS specific extended community. 6. Security Considerations There are no additional security risks introduced by this design. 7. Normative References [I-D.ietf-l3vpn-as4octet-ext-community] Rekhter, Y., Sangli, S., and D. Tappan, "Four-octet AS Specific BGP Extended Community", draft-ietf-l3vpn-as4octet-ext-community-00 (work in progress), September 2008. [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. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Authors' Addresses Dhananjaya Rao Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Email: dhrao@cisco.com Rao, et al. Expires April 24, 2009 [Page 5] Internet-Draft 4octet Extcomm generic sub-type October 2008 Pradosh Mohapatra Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Email: pmohapat@cisco.com Jeffrey Haas Arbor Networks 2727 S. State St. Ann Arbor, MI 48104 USA Email: jhaas@arbor.net Rao, et al. Expires April 24, 2009 [Page 6] Internet-Draft 4octet Extcomm generic sub-type October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Rao, et al. Expires April 24, 2009 [Page 7]