A Policy Control Mechanism in IS-IS Using Administrative Tags
RFC 5130
Network Working Group S. Previdi
Request for Comments: 5130 M. Shand, Ed.
Category: Standards Track Cisco Systems
C. Martin
iPath Services
February 2008
A Policy Control Mechanism in IS-IS Using Administrative Tags
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
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. This
document enhances the IS-IS protocol by extending the information
that an Intermediate System (IS) router can place in Link State
Protocol (LSP) Data Units for policy use. This extension will
provide operators with a mechanism to control IP prefix distribution
throughout multi-level IS-IS domains.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . . 2
3. Sub-TLV Additions . . . . . . . . . . . . . . . . . . . . . . . 2
3.1. 32-bit Administrative Tag Sub-TLV 1 . . . . . . . . . . . . 3
3.2. 64-bit Administrative Tag Sub-TLV 2 . . . . . . . . . . . . 3
4. Ordering of Tags . . . . . . . . . . . . . . . . . . . . . . . 3
5. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
9. Manageability Considerations . . . . . . . . . . . . . . . . . 5
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 6
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
12.1. Normative References . . . . . . . . . . . . . . . . . . . 6
12.2. Informative References . . . . . . . . . . . . . . . . . . 6
Previdi, et al. Standards Track [Page 1]
RFC 5130 IS-IS Admin Tags February 2008
1. Introduction
As defined in [RFC1195] and extended in [RFC3784], the IS-IS protocol
[ISO10589] may be used to distribute IPv4 prefix reachability
information throughout an IS-IS domain. In addition, thanks to
extensions made in [RFC5120] and [ISIS-IPv6], IS-IS may be used to
distribute IPv6 reachability information.
The IPv4 prefix information is encoded as TLV type 128 and 130 in
[RFC1195], with additional information carried in TLV 135 as
specified in [RFC3784] and TLV 235 as defined in [RFC5120]. In
particular, the extended IP Reachability TLV (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. TLV 235 is a derivative of TLV 135,
with the addition of Multi-Topology membership information [RFC5120].
The IPv6 prefix information is encoded as TLV 236 in [ISIS-IPv6], and
TLV 237 in [RFC5120].
This document defines 2 new sub-TLVs for TLV 135, TLV 235, TLV 236
and TLV 237 that may be used to carry administrative information
about an IP prefix.
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 BCP 14, [RFC2119].
3. Sub-TLV Additions
This document creates 2 new "Administrative Tag" sub-TLVs to be added
to TLV 135, TLV 235, TLV 236 and TLV 237. These TLVs specify one or
more 32- or 64-bit unsigned integers that may be associated with an
IP prefix. Example uses of these tags include carrying BGP standard
(or extended) communities and controlling redistribution between
levels and 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(s) is discussed in the following
subsections.
Previdi, et al. Standards Track [Page 2]
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