IS-IS Route Preference for Extended IP and IPv6 Reachability (RFC7775)
Original Publication Date: 2016-Feb-01
Included in the Prior Art Database: 2016-Mar-01
Internet Society Requests For Comment (RFCs)
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.
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 http://www.rfc-editor.org/info/rfc7775.
Ginsberg, et al. Standards Track [Page 1]
RFC 7775 IS-IS Route Preference February 2016
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