Skip to main content

Definition of an IS-IS Link Attribute Sub-TLV
draft-ietf-isis-link-attr-03

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 5029.
Authors JP Vasseur , Stefano Previdi
Last updated 2015-10-14 (Latest revision 2007-02-07)
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Formats
Reviews
Additional resources Mailing list discussion
Stream WG state (None)
Document shepherd (None)
IESG IESG state Became RFC 5029 (Proposed Standard)
Action Holders
(None)
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Ross Callon
Send notices to (None)
draft-ietf-isis-link-attr-03
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.

   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.

Intellectual Property

   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.

Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).

Vasseur & Previdi        Expires August 10, 2007                [Page 6]