Network Working Group Christian Martin INTERNET DRAFT Verzion Global Networks, Inc. Administrative Tags in IS-IS 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]