Network Working Group A. Lindem (Editor) Internet-Draft Cisco Systems, Inc Expires: July 8, 2005 N. Shen Cisco Systems R. Aggarwal Juniper Networks S. Shaffer BridgePort Networks JP. Vasseur Cisco Systems, Inc January 7, 2005 Extensions to OSPF for Advertising Optional Router Capabilities draft-ietf-ospf-cap-05.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 July 8, 2005. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Lindem (Editor), et al. Expires July 8, 2005 [Page 1] Internet-Draft OSPF Capability Extensions January 2005 It is useful for routers in an OSPF routing domain to know the capabilities of their neighbors and other routers in the OSPF routing domain. This draft proposes extensions to OSPF for advertising optional router capabilities. A new Router Information (RI) opaque LSA is proposed for this purpose. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. OSPF Router Information (RI) Opaque LSA . . . . . . . . . . . 4 2.1 OSPF Router Capabilities TLV . . . . . . . . . . . . . . . 5 2.2 Reserved OSPF Router Capability Bits . . . . . . . . . . . 6 2.3 Flooding Scope of the Router Information LSA . . . . . . . 6 3. Router Information LSA Opaque Usage and Applicability . . . . 8 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1 Normative References . . . . . . . . . . . . . . . . . . . . 11 6.2 Informative References . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 11 A. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 14 Lindem (Editor), et al. Expires July 8, 2005 [Page 2] Internet-Draft OSPF Capability Extensions January 2005 1. Introduction It is useful for routers in an OSPF routing domain to know the capabilities of their neighbors and other routers in the OSPF routing domain. This can be useful for various applications: o In MPLS Traffic Engineering (TE), it can be used as a discovery mechanism [TECAP] to announce a LSR's TE capabilities like Path Computation Server capability (Capability of an LSR to be a Path Computation Server for TE LSP path computation) or the intention of an LSR to be part of a particular MPLS TE mesh group. o For network management and troubleshooting. It gives operators a network wide view of OSPF capabilities on different routers. The presence of a capability on a given router implies that the software version supports the capability and the router is configured to support it. On the other hand, the absence of an expected capability on a particular router can imply either misconfiguration or an incorrect software version. Hence, this capability information can be used to track problems resulting from misconfiguration or an incorrect software version. OSPF uses the options field in the hello packet to advertise optional router capabilities [OSPF]. However, all the bits in this field have been allocated and there is no way to advertise new optional or MPLS TE capabilities. This document proposes extensions to OSPF to advertise these optional capabilities. For existing OSPF capabilities, this advertisement will be used primarily for informational purposes. For MPLS TE features, it is used for advertisement and discovery. Future OSPF features could also use this mechanism for advertisement and discovery. Lindem (Editor), et al. Expires July 8, 2005 [Page 3] Internet-Draft OSPF Capability Extensions January 2005 2. OSPF Router Information (RI) Opaque LSA OSPF routers will optionally advertise their optional capabilities in an area-scoped, local scope, or AS-scoped Opaque-LSA [OPAQUE]. If a router does not advertise this LSA, it does not imply that the router does not support one or more of the defined capabilities. For existing OSPF capabilities, this advertisement will be used primarily for informational purposes. For MPLS TE features, it is used for advertisement and discovery. Future OSPF features could also use this mechanism for advertisement and discovery. The RI opaque LSA will be originated when one of the advertised capabilities is configured or changed. The Router Information LSA will have an Opaque type of 4 and Opaque ID of 0. 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 | 9, 10 or 11 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 4 | 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS sequence number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS checksum | length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +- TLV's -+ | ... | The format of the TLV's within the body of a router information LSA is the same as the format used by the Traffic Engineering Extensions to OSPF [TE]. The LSA payload consists of one or more nested Type/ Length/Value (TLV) triplets. The format of each TLV is: Lindem (Editor), et al. Expires July 8, 2005 [Page 4] Internet-Draft OSPF Capability Extensions January 2005 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Length field defines the length of the value portion in octets (thus a TLV with no value portion would have a length of zero). The TLV is padded to four-octet alignment; padding is not included in the length field (so a three octet value would have a length of three, but the total size of the TLV would be eight octets). Nested TLV's are also 32-bit aligned. For example, a one byte value would have the length field set to 1, and three bytes of padding would be added to the end of the value portion of the TLV. Unrecognized types are ignored. 2.1 OSPF Router Capabilities TLV The first defined TLV in the body of an RI opaque LSA is the Router Capabilities TLV. A router advertising an RI opaque LSA SHOULD include the Router Capabilities TLV and SHOULD correctly identify the status of the capabilities defined in section 2.2. The format of the Router Capabilities TLV is as follows: Lindem (Editor), et al. Expires July 8, 2005 [Page 5] Internet-Draft OSPF Capability Extensions January 2005 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Capabilities | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type A 16 bit field set to 1. Length A 16 bit field that indicates the length of the value portion in bytes. Its set to N x 4 octets. N starts from 1 and can be increased when there is a need. Each 4 octets are referred to as a capability flag. Value This comprises one or more capability flags. For each 4 octets, the bits are indexed from the most significant to the least significant, where each bit represents one router capability. When the first 32 capabilities are defined, a new capability flag will be used to accommodate the next capability. The Router Capabilities TLV MAY be followed by optional TLV's that further specify a capability. 2.2 Reserved OSPF Router Capability Bits The following bits in the first capability flag have been assigned: Bit Capabilities 0-3 Reserved 4 OSPF graceful restart capable [GRACE] 5 OSPF graceful restart helper [GRACE] 6 OSPF Stub Router support [STUB] 7 OSPF Traffic Engineering support [TE] 8 OSPF point-to-point over LAN [P2PLAN] 9 OSPF Path Computation Server discovery [TECAP] 10 OSPF Experimental TE [EXPTE] 11-31 Future assignments 2.3 Flooding Scope of the Router Information LSA The flooding scope for a Router Information opaque LSA is determined by the LSA type. A type 9 (link-scope), type 10 (area-scoped), or a Lindem (Editor), et al. Expires July 8, 2005 [Page 6] Internet-Draft OSPF Capability Extensions January 2005 type 11 (AS-scoped) opaque LSA may be flooded. If a type 11 opaque LSA is chosen, the originating router should also advertise type 10 LSA(s) into any attached NSSA/stub area(s). An OSPF router MAY advertise different capabilities when both NSSA/stub area type 10 LSA(s) and an AS scoped type 11 opaque LSA is advertised. This allows functional capabilities to be limited in scope. For example, a router may be an area border router but only support traffic engineering (TE) in a subset of its attached areas. The choice of flooding scope is made by the advertising router and is a matter of local policy. The originating router MAY advertise multiple RI opaque LSAs as long as the flooding scopes differ. TLV flooding scope rules will be specified on a per-TLV basis. Lindem (Editor), et al. Expires July 8, 2005 [Page 7] Internet-Draft OSPF Capability Extensions January 2005 3. Router Information LSA Opaque Usage and Applicability The purpose of the Router Information (RI) opaque LSA is to advertise information relating to the aggregate OSPF router. Normally, this should be confined to TLVs with a single value or very few values. It is not meant to be a generic container to carry any and all information. The intent is to both limit the size of the RI LSA to the point where an OSPF router will always be able to contain the TLVs in a single LSA and to keep the task of determining what has changed between LSA instances reasonably simple. Hence, discretion and sound engineering judgement MUST be adhered to when deciding whether newly proposed TLV(s) in support of a new function are advertised in the RI opaque LSA or warrent the creation of a function specific opaque LSA. Lindem (Editor), et al. Expires July 8, 2005 [Page 8] Internet-Draft OSPF Capability Extensions January 2005 4. Security Considerations The function described in this document does not create any new security issues for the OSPF protocol. Security considerations for the base OSPF protocol are covered in [OSPF]. Lindem (Editor), et al. Expires July 8, 2005 [Page 9] Internet-Draft OSPF Capability Extensions January 2005 5. IANA Considerations A new opaque LSA type will need to be assigned by IANA. Additionally, IANA will need to have registries for the Router Information opaque LSA TLV's. The TLV assignee will be responsible for allocation of any sub-TLV's for the IANA assigned TLV. All TLV's and sub-TLV's will be subject to OSPF WG review. Lindem (Editor), et al. Expires July 8, 2005 [Page 10] Internet-Draft OSPF Capability Extensions January 2005 6. References 6.1 Normative References [OSPF] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [RFC2119] Bradner, S., "Key words for use in RFC's to Indicate Requirement Levels", RFC 2328, March 1977. [TE] Katz, D., Yeung, D. and K. Kompella, "Traffic Engineering Extensions to OSPF", RFC 3630, September 2003. 6.2 Informative References [EXPTE] Srisuresh, P. and P. Joseph, "OSPF OSPF-TE: An experimental extension to OSPF for Traffic Engineering", draft-srisuresh-ospf-te-07.txt (work in progress). [GRACE] Moy, J., Pillay-Esnault, P. and A. Lindem, "Graceful OSPF Restart", RFC 3623, November 2003. [OPAQUE] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July 1998. [P2PLAN] Shen, N. and A. Zinin, "Point-to-point operation over LAN in link-state routing protocols", draft-ietf-isis-igp-p2p-over-lan-05.txt (work in progress). [STUB] Retana, A., Nguyen, L., White, R., Zinin, A. and D. McPherson, "OSPF Stub Router Advertisement", RFC 3137, June 2001. [T3CAP] Vasseur, JP., Psenak, P., Yasukawa, S. and JL. Le Roux, "OSPF MPLS Traffic Engineering Capabilities", draft-vasseur-ospf-te-caps-00.txt (work in progress). Authors' Addresses Acee Lindem Cisco Systems, Inc 7025 Kit Creek Road Research Triangle Park, NC 27709 USA EMail: acee@cisco.com Lindem (Editor), et al. Expires July 8, 2005 [Page 11] Internet-Draft OSPF Capability Extensions January 2005 Naiming Shen Cisco Systems 225 West Tasman Drive San Jose, CA 95134 USA EMail: naiming@cisco.com Rahul Aggarwal Juniper Networks 1194 N. Mathilda Ave. Sunnyvale, CA 94089 USA EMail: rahul@juniper.net Scott Shaffer BridgePort Networks One Main Street, 7th Floor Cambridge, MA 02142 USA EMail: sshafferl@bridgeport-networks.com Jean-Philippe Vasseur Cisco Systems, Inc 300 Beaver Brook Road Boxborough, MA 01719 USA EMail: jpv@cisco.com Lindem (Editor), et al. Expires July 8, 2005 [Page 12] Internet-Draft OSPF Capability Extensions January 2005 Appendix A. Acknowledgments The idea for this work grew out of a conversation with Andrew Partan and we would like to thank him for his contribution. The authors would like to thanks Peter Psenak for his review and helpful comments early versions of the draft. Comments from Abhay Roy, Vishwas Manral, and Vivek Dubey were incorporated into the final draft version. The RFC text was produced using Marshall Rose's xml2rfc tool. Lindem (Editor), et al. Expires July 8, 2005 [Page 13] Internet-Draft OSPF Capability Extensions January 2005 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. 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Disclaimer of Validity 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. Copyright Statement Copyright (C) The Internet Society (2005). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Lindem (Editor), et al. Expires July 8, 2005 [Page 14]