NetworkingNetwork Working Group JP. VasseurInternet-DraftRequest for Comments: 5029 S. PrevidiIntended status:Category: Standards Track Cisco Systems, IncExpires: August 10, 2007 February 6,September 2007 Definition of an IS-IS Link Attributesub-TLV draft-ietf-isis-link-attr-03.txtSub-TLV Status ofthisThis MemoBy 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 ofThis document specifies an Internet standards track protocol for the InternetEngineering Task Force (IETF), its areas,community, andits working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents validrequests discussion and suggestions fora maximumimprovements. 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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].Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3....................................................2 1.1. Terminology ................................................2 2.Link-attributes sub-TLV format . . . . . . . . . . . . . . . . 3Link-Attributes Sub-TLV Format ..................................2 3. Interoperability withrouters non supporting this capability . . . . . . . . . . . . . . . . . . . . . . . . . . 3Routers Not Supporting This Capability ....3 4. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 4.............................................3 5. Security Considerations. . . . . . . . . . . . . . . . . . . . 4.........................................3 6. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 4................................................3 7. References. . . . . . . . . . . . . . . . . . . . . . . . . . 4......................................................4 7.1. Normative References. . . . . . . . . . . . . . . . . . . 4.......................................4 7.2. Informative References. . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 6.....................................4 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 unitswhichthat 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-ISmetricsmetrics, 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]. 1.1 Terminology 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]. 2.Link-attributes sub-TLV formatLink-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 the link-attribute has a length of 2 octets. This sub-TLV is OPTIONAL and MUST appear at most once for a single IS neighbor. If a receivedLSPLink State Packet (LSP) contains more than one Link-Attribute Sub-TLV, an implementationMAYSHOULD 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(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 withrouters non supporting this capabilityRouters Not Supporting This Capability A router not supporting the link-attribute sub-TLV will just silently ignore this sub-TLV. 4. IANA Considerations IANAwill assign a newhas assigned codepoint 19 for the link-attribute sub-TLV defined in this document and carried within TLV 22.Suggested value is 19 (to be assigned by IANA).IANAis requested to createhas created a registry for bit values inside the link-attributes sub-TLV. The initial contents of this registrywill be:are as follows Value Name Reference ----- ---- --------- 0x1 Local Protection Available[This Document][RFC5029] 0x2 Link Excluded from Local Protection[This Document][RFC5029] 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][RFC3567], should be applied if there is high risk resulting from the modification of capability information. 6. Acknowledgements The authors would like to thank Mike Shand, LesGinsbergGinsberg, and Bill Fenner for their useful comments. 7. References 7.1. Normative References [IS-IS] "Intermediate System to Intermediate System Intra-DomainRouteingRouting 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 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 USAEmail:EMail: jpv@cisco.com Stefano Previdi Cisco Systems, Inc Via Del Serafico 200Roma,Roma 00142 ItalyEmail:EMail: sprevidi@cisco.com 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. 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, THE IETF TRUST 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. 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