Browse Prior Art Database

IS-IS Route Preference for Extended IP and IPv6 Reachability (RFC7775) Disclosure Number: IPCOM000245330D
Original Publication Date: 2016-Feb-01
Included in the Prior Art Database: 2016-Mar-01
Document File: 22 page(s) / 24K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

L. Ginsberg: AUTHOR [+2]


[RFC5302] defines the route preference rules as they apply to TLVs 128 and 130. [RFC5305] introduced the IP Extended Reachability TLV 135 but did not explicitly adapt the route preference rules defined in [RFC5302] for the new TLV. [RFC5308] defines the IPv6 Reachability TLV 236 and does include an explicit statement regarding route preference -- but the statement introduces use of the up/down bit in advertisements that appear in Level 2 LSPs, which is inconsistent with statements made in [RFC5302] and [RFC5305]. This document defines explicit route preference rules for TLV 135, revises the route preference rules for TLV 236, and clarifies the usage of the up/down bit when it appears in TLVs in Level 2 LSPs. This document is a clarification (NOT a correction) of [RFC5302] and [RFC5305]; it is a correction of the route preference rules defined in [RFC5308] to be consistent with the rules for IPv4. It also makes explicit that the same rules apply to the Multi-Topology (MT) equivalent TLVs 235 and 237.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 12% of the total text.

Internet Engineering Task Force (IETF)                       L. Ginsberg Request for Comments: 7775                                 Cisco Systems Updates: 5308                                               S. Litkowski Category: Standards Track                        Orange Business Service ISSN: 2070-1721                                               S. Previdi                                                            Cisco Systems                                                            February 2016

       IS-IS Route Preference for Extended IP and IPv6 Reachability


   In existing specifications, the route preferences for IPv4/IPv6    Extended Reachability TLVs are not explicitly stated.  There are also    inconsistencies in the definition of how the up/down bit applies to    route preference when the prefix advertisement appears in Level 2    Link State Protocol Data Units (LSPs).  This document addresses these    issues.

   This document updates RFC 5308.

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

 Ginsberg, et al.             Standards Track                    [Page 1]
 RFC 7775                 IS-IS Route Preference            February 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    ( 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.

   This document may contain material from IETF Documents or IETF    Contributions published or made publicly available before November    10, 20...