Networking Working Group JP. Vasseur Internet-Draft S. Previdi Intended status: Standards Track Cisco Systems, Inc Expires: August 10, 2007 February 6, 2007 Definition of an IS-IS Link Attribute sub-TLV draft-ietf-isis-link-attr-03.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 August 10, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document defines a sub-TLV called "Link-attributes" carried within the TLV 22 and used to flood some link characteristics. 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]. Vasseur & Previdi Expires August 10, 2007 [Page 1] Internet-Draft draft-ietf-isis-link-attr-03.txt February 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Link-attributes sub-TLV format . . . . . . . . . . . . . . . . 3 3. Interoperability with routers non supporting this capability . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 6 Vasseur & Previdi Expires August 10, 2007 [Page 2] Internet-Draft draft-ietf-isis-link-attr-03.txt February 2007 1. Introduction [IS-IS] specifies the IS-IS protocol (ISO 10589) with extensions to support IPv4 in [RFC1195]. A router advertises one or several Link State Protocol data units which are composed of variable length tuples called TLVs (Type-Length-Value). [RFC3784] 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 "Link-attributes" carried within the extended IS reachability TLV (type 22) specified in [RFC3784]. 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 ([RFC3784]): 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. 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 MUST appear at most once for a single IS neighbor. If a received LSP contains more than one Link-Attribute Sub-TLV, an implementation MAY decide to consider only the first encountered instance. The following bits are defined: Local Protection Available (0x01). When set, this indicates that the link is protected by means of some local protection mechanism (e.g [RFC4090]). 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. 3. Interoperability with routers non supporting this capability A router not supporting the link-attribute sub-TLV will just silently ignore this sub-TLV. Vasseur & Previdi Expires August 10, 2007 [Page 3] Internet-Draft draft-ietf-isis-link-attr-03.txt February 2007 4. IANA Considerations IANA will assign a new codepoint for the link-attribute sub-TLV defined in this document and carried within TLV 22. Suggested value is 19 (to be assigned by IANA). IANA is requested to create a registry for bit values inside the link-attributes sub-TLV. The initial contents of this registry will be: Value Name Reference ----- ---- --------- 0x1 Local Protection Available [This Document] 0x2 Link Excluded from Local Protection [This Document] Further values are to be allocated by the Standards Action process defined in [RFC2434], with Early Allocation (defined in [RFC4020]) permitted. 5. Security Considerations Any new security issues raised by the procedures in this document depend upon the opportunity for LSPs to be snooped and modified, the ease/difficulty of which has not been altered. As the LSPs may now contain additional information regarding router capabilities, this new information would also become available to an attacker. Specifications based on this mechanism need to describe the security considerations around the disclosure and modification of their information. Note that an integrity mechanism, such as one defined in [RFC3567] should be applied if there is high risk resulting from modification of capability information. 6. Acknowledgements The authors would like to thank Mike Shand, Les Ginsberg and Bill Fenner for their useful comments. 7. References 7.1. Normative References [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. [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, December 1990. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Vasseur & Previdi Expires August 10, 2007 [Page 4] Internet-Draft draft-ietf-isis-link-attr-03.txt February 2007 Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate System (IS-IS) Extensions for Traffic Engineering (TE)", RFC 3784, June 2004. [RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of Standards Track Code Points", BCP 100, RFC 4020, February 2005. 7.2. Informative References [RFC3567] Li, T. and R. Atkinson, "Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567, July 2003. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. Authors' Addresses JP Vasseur Cisco Systems, Inc 1414 Massachusetts Avenue Boxborough, MA 01719 USA Email: jpv@cisco.com Stefano Previdi Cisco Systems, Inc Via Del Serafico 200 Roma, 00142 Italy Email: sprevidi@cisco.com Vasseur & Previdi Expires August 10, 2007 [Page 5] Internet-Draft draft-ietf-isis-link-attr-03.txt February 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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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