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.
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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.
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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.
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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
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