Network Working Group K. Kompella Internet Draft Juniper Networks Updates: 2740 October 2002 Category: Standards Track Expires: April 2003 OSPFv2 Opaque LSAs in OSPFv3 draft-kompella-ospf-opaquev2-00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Abstract This memo specifies how OSPF version 2 Opaque Link State Advertisements can be carried in OSPF version 3. Kompella Standards Track [Page 1] Internet Draft OSPFv2 Opaque LSAs in OSPFv3 October 2002 1. Introduction RFC 2370 [OPAQUE] describes the notion of an "opaque" Link State Advertisement (LSA) -- as the RFC says, an LSA that provides "a generalized mechanism to allow for the future extensibility of OSPF". This has certainly proved useful, for example in defining Grace LSAs [HITLESS] and OSPF v2 Traffic Engineering LSAs [OSPF-TE]. RFC 2370 also defines the format that opaque LSAs take in OSPF version 2 [OSPFv2], and defines three flooding scopes for such LSAs: link-local, area-local and Autonomous System (AS)-wide. OSPF version 3 [OSPFv3] inherently supports the notion of opaque LSAs in that the flooding scope of an LSA is explicitly stated in the LSA header. OSPF v3 also specifies how LSAs with unrecognized function codes are to be handled. This memo specifies how OSPF version 2 opaque LSAs can be carried in OSPF version 3. This allows the reuse of the specifications of OSPF v2 Opaque LSAs, as well as the code to support them, in OSPF v3. In a nutshell, an OSPF v3 LS Function Code is defined to indicate that the LSA is of type OSPF v2 Opaque LSAs; the OSPF v3 Link State ID is formatted the same as in the OSPF v2 Opaque LSA; and the body of the OSPF v3 LSA is identical to the body of the OSPF v2 Opaque LSA. 2. Opaque LSAs An Opaque LSA in OSPF v2 is formatted as follows [OPAQUE, A.2]: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS age | Options | LS Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Opaque Type | Opaque ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | Opaque Information | + + | ... | Kompella Standards Track [Page 2] Internet Draft OSPFv2 Opaque LSAs in OSPFv3 October 2002 The LS Type is 9, 10, or 11 depending on whether the Opaque LSA's flooding scope is link-local, area-local or AS-wide (respectively). The above OSPF v2 Opaque LSA is formatted as follows as an OSPF v3 LSA: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS age |1|X|Y| OSPFv2 Opaque LSA | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | Opaque Information | + + | ... | The U bit in the LS Type is set to 1. The LS Function Code is set to 10 [to be ratified by the OSPF WG], indicating that the LSA type is 'OSPF v2 Opaque LSA'. The XY bits are set to reflect the flooding scope: OSPFv2 Opaque LSA of LS Type X Y -------------- --- 9 0 0 10 0 1 11 1 0 The OSPF v3 LSA's Link State ID is formatted as one octet of Opaque Type, and 3 octets of Opaque ID (i.e., exactly as the Link State ID of the OSPF v2 Opaque LSA). The body of the OSPF v3 LSA is octet-for-octet identical to the OSPF v2 Opaque Information. Kompella Standards Track [Page 3] Internet Draft OSPFv2 Opaque LSAs in OSPFv3 October 2002 2.1. Processing OSPF v2 Opaque LSAs An OSPF v3 implementation encountering an LSA of type 'OSPF v2 Opaque LSA' MUST follow the rules regarding handling and flooding as defined by the U and XY bits, as defined in [OSPFv3]. In addition, an OSPF v3 implementation MAY further process an OSPF v2 Opaque LSA as an OSPF v2 implementation would, e.g., it might use a Grace-LSA to accomplish (or assist in) hitless restart of OSPF v3; or it might build a Traffic Engineering database using the opaque TE LSAs. It is the intent of this memo to maximize code (and specification) reuse between OSPF v2 and OSPF v3 in this regard. Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [OPAQUE] Coltun, R., "The OSPF Opaque LSA Option," RFC 2370, July 1998 [OSPFv2] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998 [OSPFv3] Coltun, R., D. Ferguson, and J. Moy, "OSPF for IPv6", RFC 2740, December 1999 Informative References [HITLESS] Moy, J., "Hitless OSPF Restart", work in progress [OSPF-TE] Katz, D., D. Yeung, and K. Kompella, "Traffic Engineering Extensions to OSPF Version 2", work in progress Security Considerations The flooding and handling of LSAs has already been specified in the [OSPFv3]; this memo only defines a new LS Function Code, and the format of the LS body. The OSPF v3 security mechanisms to prevent tampering and spoofing of LSAs suffice. Kompella Standards Track [Page 4] Internet Draft OSPFv2 Opaque LSAs in OSPFv3 October 2002 Acknowledgments Many thanks to Quaizar Vohra, with whom much of this was discussed. Authors' Addresses Kireeti Kompella Juniper Networks, Inc. 1194 N. Mathilda Ave Sunnyvale, CA 94089 Email: kireeti@juniper.net IPR Notice The IETF takes no position regarding the validity or scope of any intellectual property 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; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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