IS-IS Prefix Attributes for Extended IPv4 and IPv6 Reachability
RFC 7794
Internet Engineering Task Force (IETF) L. Ginsberg, Ed.
Request for Comments: 7794 Cisco Systems
Category: Standards Track B. Decraene
ISSN: 2070-1721 Orange
S. Previdi
Cisco Systems
X. Xu
Huawei
U. Chunduri
Ericsson
March 2016
IS-IS Prefix Attributes for Extended IPv4 and IPv6 Reachability
Abstract
This document introduces new sub-TLVs to support advertisement of
IPv4 and IPv6 prefix attribute flags and the source router ID of the
router that originated a prefix advertisement.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7794.
Ginsberg, et al. Standards Track [Page 1]
RFC 7794 IS-IS Prefix Attributes March 2016
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. New Sub-TLVs for Extended Reachability TLVs . . . . . . . . . 3
2.1. IPv4/IPv6 Extended Reachability Attribute Flags . . . . . 4
2.2. IPv4/IPv6 Source Router ID . . . . . . . . . . . . . . . 5
2.3. Advertising Router IDs . . . . . . . . . . . . . . . . . 6
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Normative References . . . . . . . . . . . . . . . . . . 7
5.2. Informative References . . . . . . . . . . . . . . . . . 8
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
Ginsberg, et al. Standards Track [Page 2]
RFC 7794 IS-IS Prefix Attributes March 2016
1. Introduction
IS-IS is a link-state routing protocol defined in [ISO10589] and
[RFC1195]. Extensions in support of advertising new forms of
IPv4/IPv6 prefix reachability are defined in [RFC5305], [RFC5308],
and [RFC5120].
There are existing use cases in which knowing additional attributes
of a prefix is useful.
It is useful to know whether or not an advertised prefix is directly
connected to the advertising router. In the case of Segment Routing
as described in [SR], knowing whether or not a prefix is directly
connected determines what action should be taken as regards
processing of labels associated with an incoming packet.
It is useful to know what addresses can be used as addresses of the
node in support of services (e.g., Remote Loop Free Alternate (RLFA)
endpoint).
Current formats of the Extended Reachability TLVs for both IPv4 and
IPv6 are fixed and do not allow the introduction of additional flags
without backwards compatibility issues. Therefore, this document
defines a new sub-TLV that supports the advertisement of attribute
flags associated with prefix advertisements.
In cases where multiple node addresses are advertised by a given
router, it is also useful to be able to associate all of these
addresses with a single Router ID even when prefixes are advertised
Show full document text