Network Working Group Luca Martini Internet Draft Keyur Patel Expiration Date: April 2007 Cisco Systems Inc. October 2006 Route Distinguisher Zero Value Usage draft-martini-l3vpn-rd-zero-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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract The behaviour that must be followed when an route distinguisher (RD) of value zero is received is not clearly defined in rfc4364. This document clarifies the use of an RD with a value of zero in the context defined in rfc 4364. Martini & Keyur [Page 1] Internet Draft draft-martini-l3vpn-rd-zero-00.txt October 2006 Table of Contents 1 Specification of Requirements ........................ 2 2 Introduction ......................................... 2 3 RFC4364 definitions .................................. 2 3.1 Usage of RD value of zero ........................... 3 4 Full Copyright Statement ............................. 3 5 Intellectual Property Statement ...................... 3 6 IANA Considerations .................................. 4 7 Normative References ................................. 4 8 Author Information ................................... 4 1. 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. 2. Introduction This document refines the Route Distinguisher semantics detailed in [RFC4364]. The Route Distinguisher consist of an 8-byte value whose encoding is detailed in [RFC4364]. The Route Distinguisher is used in conjunction with VPN prefixes and VPN nexthops in VPN networks to solely allow one to create distinct routes to a common IPv4 address prefix. 3. RFC4364 definitions Currently in [RFC4364] section 4.3.2, the RD is used with a value of 0 in the next hop field of the BGP NLRI. This is a special case that is allowed by the design. In section 4.2 of [RFC4364], the enconding of the RD for type 0 is defines as a type field , and a value field. If the type field is 0, then the value field in interpreted as containing an autonomous system number (ASN), and a assigned Number subfield. The ASN cannot contain 0 as it is a reserved ASN number. Martini & Keyur [Page 2] Internet Draft draft-martini-l3vpn-rd-zero-00.txt October 2006 3.1. Usage of RD value of zero Whenever the RD is used within the VPN nexthop field of the BGP NLRI, the RD is used with the value of 0. However whenever the RD is used with VPN prefix field of the BGP NLRI , the Route Distinguisher MUST never be used with the value of 0. Hence, VPN routes received with the Route Distinguisher value of 0 MUST be discarded with an appropriate error. 4. Full Copyright Statement Copyright (C) The Internet Society (2006). 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. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 5. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. 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 Martini & Keyur [Page 3] Internet Draft draft-martini-l3vpn-rd-zero-00.txt October 2006 this standard. Please address the information to the IETF at ietf- ipr@ietf.org. 6. IANA Considerations This document has no IANA Actions. 7. Normative References [RFC4364]] "BGP/MPLS IP Virtual Private Networks (VPNs)" E. Rosen, Y. Rekhter, RFC 4364 February 2006 8. Author Information Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 e-mail: lmartini@cisco.com Keyur Patel 510 McCarthy Blvd. Milpitas , CA, 95035 e-mail: keyupate@cisco.com Martini & Keyur [Page 4]