OSPF Application-Specific Link Attributes
RFC 8920

Document Type RFC - Proposed Standard (October 2020; No errata)
Authors Peter Psenak  , Les Ginsberg  , Wim Henderickx  , Jeff Tantsura  , John Drake 
Last updated 2020-10-22
Replaces draft-ppsenak-ospf-te-link-attr-reuse
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Stream WG state Submitted to IESG for Publication
Document shepherd Yingzhen Qu
Shepherd write-up Show (last changed 2020-06-04)
IESG IESG state RFC 8920 (Proposed Standard)
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Responsible AD Alvaro Retana
Send notices to Acee Lindem <acee@cisco.com>, Yingzhen Qu <yingzhen.qu@futurewei.com>, aretana.ietf@gmail.com
IANA IANA review state Version Changed - Review Needed
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Internet Engineering Task Force (IETF)                    P. Psenak, Ed.
Request for Comments: 8920                                   L. Ginsberg
Category: Standards Track                                  Cisco Systems
ISSN: 2070-1721                                            W. Henderickx
                                                                   Nokia
                                                             J. Tantsura
                                                                  Apstra
                                                                J. Drake
                                                        Juniper Networks
                                                            October 2020

               OSPF Application-Specific Link Attributes

Abstract

   Existing traffic-engineering-related link attribute advertisements
   have been defined and are used in RSVP-TE deployments.  Since the
   original RSVP-TE use case was defined, additional applications (e.g.,
   Segment Routing Policy and Loop-Free Alternates) that also make use
   of the link attribute advertisements have been defined.  In cases
   where multiple applications wish to make use of these link
   attributes, the current advertisements do not support application-
   specific values for a given attribute, nor do they support indication
   of which applications are using the advertised value for a given
   link.  This document introduces new link attribute advertisements in
   OSPFv2 and OSPFv3 that address both of these shortcomings.

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 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8920.

Copyright Notice

   Copyright (c) 2020 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
   (https://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
     1.1.  Requirements Language
   2.  Requirements Discussion
   3.  Existing Advertisement of Link Attributes
   4.  Advertisement of Link Attributes
     4.1.  OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA
   5.  Advertisement of Application-Specific Values
   6.  Reused TE Link Attributes
     6.1.  Shared Risk Link Group (SRLG)
     6.2.  Extended Metrics
     6.3.  Administrative Group
     6.4.  Traffic Engineering Metric
   7.  Maximum Link Bandwidth
   8.  Considerations for Extended TE Metrics
   9.  Local Interface IPv6 Address Sub-TLV
   10. Remote Interface IPv6 Address Sub-TLV
   11. Attribute Advertisements and Enablement
   12. Deployment Considerations
     12.1.  Use of Legacy RSVP-TE LSA Advertisements
     12.2.  Interoperability, Backwards Compatibility, and Migration
            Concerns
       12.2.1.  Multiple Applications: Common Attributes with RSVP-TE
       12.2.2.  Multiple Applications: Some Attributes Not Shared with
               RSVP-TE
       12.2.3.  Interoperability with Legacy Routers
       12.2.4.  Use of Application-Specific Advertisements for RSVP-TE
   13. Security Considerations
   14. IANA Considerations
     14.1.  OSPFv2
     14.2.  OSPFv3
   15. References
     15.1.  Normative References
     15.2.  Informative References
   Acknowledgments
   Contributors
   Authors' Addresses

1.  Introduction

   Advertisement of link attributes by the OSPFv2 [RFC2328] and OSPFv3
   [RFC5340] protocols in support of traffic engineering (TE) was
   introduced by [RFC3630] and [RFC5329], respectively.  It has been
   extended by [RFC4203], [RFC7308], and [RFC7471].  Use of these
   extensions has been associated with deployments supporting Traffic
   Engineering over Multiprotocol Label Switching (MPLS) in the presence
   of the Resource Reservation Protocol (RSVP), more succinctly referred
   to as RSVP-TE [RFC3209].

   For the purposes of this document, an application is a technology
   that makes use of link attribute advertisements, examples of which
   are listed in Section 5.

   In recent years, new applications have been introduced that have use
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