ISIS WG Internet Draft Jean-Philippe Vasseur Stefano Previdi Cisco Systems Document: draft-vasseur-isis-link-attr- 01.txt Expires: January 2005 July 2004 Definition of an IS-IS Link Attribute sub-TLV draft-vasseur-isis-link-attr-01.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [i]. 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. Abstract This document defines a sub-TLV called ææLink-attributesÆÆ carried within the TLV 22 and used to flood some link characteristics. Conventions used in this document Vasseur and Previdi [Page 1] 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 [ii]. Table of contents 1. Introduction...................................................2 2. Link-attributes sub-TLV format.................................2 3. Interoperability with routers non supporting this capability...3 4. Security considerations........................................3 5. Intellectual Property Considerations...........................3 6. Acknowledgments................................................4 7. Intellectual property considerations...........................4 7.1 IPR Disclosure Acknowledgement.............................5 8. References.....................................................5 Normative references..............................................5 Informative references............................................5 9. Author's Addresses.............................................5 10. Full Copyright Statement......................................6 1. Introduction [IS-IS] specifies the IS-IS protocol (ISO 10589) with extensions to support IPv4 in [IS-IS-IP]. A router advertises one or several Link State Protocol data units which are composed of variable length tuples called TLVs (Type-Length-Value). [IS-IS-TE] defines a set of new TLVs whose aims are to add more information about links characteristics, increase the range of IS-IS metrics and optimize the encoding of IS-IS prefixes. This document defines a new sub-TLV named ææLink-attributesÆÆ carried within the extended IS reachability TLV (type 22) specified in [IS- IS-TE]. 2. Link-attributes sub-TLV format The link-attribute sub-TLV is carried within the TLV 22 and has a format identical to the sub-TLV format used by the Traffic Engineering Extensions for IS-IS [IS-IS-TE]: 1 octet of sub-type, 1 octet of length of the value field of the sub-TLV followed by the value field - - in this case, a 16 bit flags field. Vasseur and Previdi [Page 2] The Link-attribute sub-type is 19 (to be assigned by IANA) and has a length of 2 octets. This sub-TLV is OPTIONAL and MAY appear at most once for a single IS neighbor. The following bits are defined (values to be confirmed by IANA): Local Protection Available (0x01). When set, this indicates that the link is protected by means of some local protection mechanism (e.g [FRR]). Link excluded from local protection path (0x02). When set, this link SHOULD not be included in any computation of a repair path by any other router in the routing area. The triggers for setting up this bit are out of the scope of this document. Such link characteristics has several applications such as constrained shortest path computation for a Traffic Engineering Label Switched (TE LSP) path or the triggering of specific actions in the context of IS-IS SPF computation. Local maintenance required (0x04). When set, this indicates that the link will be put out of service and will consequently be shortly unavailable. The set of actions triggered by other nodes is out of the scope of this document. An example of the usage of this bit is provided in [GR-SHUT]. 3. Interoperability with routers non supporting this capability A router not supporting the link-attribute sub-TLV MUST just silently ignore this sub-TLV. Where the information in the link attributes sub-TLV is used to affect the IS-IS SPF calculation, additional information indicating which routers are using this information is required to insure such usage does not result in loops or black holes. How this additional information is conveyed is outside the scope of this document. 4. Security considerations No new security issues are raised in this document. 5. Intellectual Property Considerations 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 Vasseur and Previdi [Page 3] 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. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. The IETF has been notified of intellectual property rights claimed in regard to some or all of the specification contained in this document. For more information consult the online list of claimed rights. 6. Acknowledgments The authors would like to thank Mike Shand and Les Ginsberg for their useful comments. 7. Intellectual property considerations 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 this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Vasseur and Previdi [Page 4] 7.1 IPR Disclosure Acknowledgement By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 8. References Normative references [RFC] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels," RFC 2119. [IS-IS] "Intermediate System to Intermediate System Intra-Domain Routeing Exchange Protocol for use in Conjunction with the Protocol for Providing the Connectionless-mode Network Service (ISO 8473)", ISO 10589. [IS-IS-IP] Callon, R., RFC 1195, "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, December 1990. [IS-IS-TE] H. Smit, T. Li, ææIS-IS extensions for traffic engineeringÆÆ, RFC 3784. Informative references [FRR] Ping Pan, et al, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt, December 2003. [GR-SHUT], Z. Ali et al, ææGraceful Shutdown in MPLS Traffic Engineering NetworksÆÆ, draft-ali-mpls-graceful-shutdown-00.txt, July 2005, work in progress. 9. Author's Addresses Jean-Philippe Vasseur CISCO Systems, Inc. 300 Beaver Brook Boxborough, MA 01719 USA Email: jpv@cisco.com Stefano Previdi CISCO Systems, Inc. Via Del Serafico 200 00142 - Roma ITALY Email: sprevidi@cisco.com Vasseur and Previdi [Page 5] 10. Full Copyright Statement "Copyright (C) The Internet Society (year). 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." Vasseur and Previdi [Page 6]