OSPF Application-Specific Link Attributes
RFC 8920
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.
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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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