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Network Working Group                                   Christian Martin
INTERNET DRAFT                             Verzion Global Networks, Inc.



                      Administrative Tags in IS-IS
                 <draft-martin-isis-admin-tags-01.txt>


1. Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026.

   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.


2. Abstract

   This document describes an extension to the IS-IS protocol to add
   operational capabilities that allow for ease of management and
   control over IP prefix distribution within an IS-IS domain.  The IS-
   IS protocol is specified in [1], with extensions for supporting IPv4
   specified in [2] and further enhancements for Traffic Engineering [4]
   in [3].

   This document enhances the IS-IS protocol by extending the
   information that a Intermediate System (IS) [router] can place in
   Link State Protocol Data Units (LSPs) as specified in [2].  This
   extension will provide operators with a mechanism to control IP
   prefix distribution throughout multi-level IS-IS domains.





Martin                                                  [Page 1]


INTERNET DRAFT                                                 May 2001


3. Introduction

   As defined in [2] and extended in [3], the IS-IS protocol may be used
   to distribute IP prefix reachibility information throughout an IS-IS
   domain.  The IP prefix information is encoded as TLV type 130 in [2],
   with additional information carried in TLV 135 as specified in [3].
   In particular, the extended IP Reachibilty TLV (135) contains support
   for a larger metric space, an up/down bit to indicate redistribution
   between different levels in the hierarchy, an IP prefix, and one or
   more sub-TLVs that can be used to carry specific information about
   the prefix.

   As of this writing no sub-TLVs have been defined; however, this draft
   proposes a new sub-TLV that may be used to carry administrative
   information about an IP prefix.


4. Sub-TLV Additions

   This draft proposes a new "Administrative Tag" sub-TLV to be added to
   TLV 135.  This TLV specifies a 32 bit unsigned integer that may be
   associated with an IP prefix.  Example uses of this tag include
   controlling redistribution between areas, different routing
   protocols, or multiple instances of IS-IS running on the same router.

   The methods for which their use is employed is beyond the scope of
   this document and left to the implementer and/or operator.

   The encoding of the sub-TLV is discussed in the following subsection.


4.1. Administrative Tag Sub-TLV [TBA]

   This sub-TLV [TBA] shall be used to associate an integer value with
   an IP prefix such that it may be used in routing policy to control
   the distribution of routing information within an IS-IS domain.  The
   Administrative Tag shall be encoded as a 4 octet unsigned integer.



Martin                                                  [Page 2]


INTERNET DRAFT                                                 May 2001


   See the "IANA Considerations" section for additional information.


5. Security Considerations

   This document raises no new security issues for IS-IS, as any
   annotations to IP prefixes should not pass outside the administrative
   control of the network operator of the IS-IS domain.  Such an
   allowance would violate the spirit of Interior Gateway Protocols in
   general and IS-IS in particular.


6. IANA Considerations

   The value of the Administrative Tag sub-TLV [TBA] must be allocated.


7. Acknowledgments

   The author would like to thank Henk Smit for clarifying the best
   place to describe this new information, Danny McPherson for his
   comments and assistance with formatting, and Tony Li for useful
   comments on this draft.


8. References

   [1] "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.

   [2] Callon, R., RFC 1195, "Use of OSI IS-IS for routing in TCP/IP and
       dual environments", RFC 1195, December 1990.

   [3] Li, T., and Smit, H., "IS-IS extensions for Traffic Engineering",
       Internet Draft, "Work in Progress", September 2000.

   [4] Adwuche, D., Malcolm, J., Agogbua, M., O'Dell, M. and McManus,
       J., "Requirements for Traffic Engineering Over MPLS," RFC 2702,
       September 1999.








Martin                                                  [Page 3]


INTERNET DRAFT                                                 May 2001


10. Author's Address

   Christian Martin
   Verizon Global Networks, Inc.
   1880 Campus Commons Dr
   Reston, VA 20191
   Email: cmartin@verizongni.com
   Voice: 1 (703) 2954394
   Fax: 1 (703) 2954279










































Martin                                                  [Page 4]


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