Network Working Group Christian Martin INTERNET DRAFT Verizon Global Networks, Inc Expiration Date: October, 2001 April 2001 Administrative Tags in IS-IS Status This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. 1.0 Abstract This document describes an extension to the IS-IS protocol to add operational capabilities that allow for easier management of 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 information may be of use to operators who must control the way IP prefix information is distributed throughout a multi-level, large scale IS-IS topology. 2. Conventions used in this document 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 [4]. 3.0 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, the 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 two new sub-TLVs that may be used to carry administrative information about an IP prefix. This document is a publication of the IS-IS Working Group within the IETF, and is a contribution to ISO IEC JTC1/SC6, for eventual inclusion with ISO 10589. 4.0 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. One use for this tag would be for 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 implemented is beyond the scope of this document and is left to the operators of IS-IS networks to decide. It is assumed, however, that vendors will provide tools to match and set these tags in routing policy configuration tools. The encoding of this new TLV is as follows: 4.1 Sub-TLV : Administrative Tag This sub-TLV 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. 5.0 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. 6.0 Acknowledgments The author would like to thank Henk Smit for clarifying the best place to describe this new information, and Tony Li for useful comments on this draft. 7.0 References [1] ISO 10589, "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)" [Also republished as RFC 1142] [2] RFC 1195, "Use of OSI IS-IS for routing in TCP/IP and dual environments", R.W. Callon, Dec. 1990 [3] draft-ietf-isis-traffic-02.txt, "IS-IS extensions for Traffic Engineering", T. Li, H. Smit, Sep. 2000 [4] RFC 2702, "Requirements for Traffic Engineering Over MPLS," D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, and J. McManus, September 1999. 9.0 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 Expiration Date: October, 2001