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Versions: 00 01

   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
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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





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   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.




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   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


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   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.



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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


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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."





































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