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IGP Flexible Algorithm

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc: Christian Hopps <>, The IESG <>,,,,,,
Subject: Protocol Action: 'IGP Flexible Algorithm' to Proposed Standard (draft-ietf-lsr-flex-algo-25.txt)

The IESG has approved the following document:
- 'IGP Flexible Algorithm'
  (draft-ietf-lsr-flex-algo-25.txt) as Proposed Standard

This document is the product of the Link State Routing Working Group.

The IESG contact persons are Alvaro Retana, Andrew Alston and John Scudder.

A URL of this Internet Draft is:

Ballot Text

Technical Summary:

This document provides extensions to OSPF and IS-IS to use different algorithms
to compute the paths to different prefixes. Since not all nodes in the
computation domain (i.e., an OSPF or IS-IS area) may support every algorithm, SR
or SRv6 is used to between nodes.

Working Group Summary:

The was good collaboration on the document. The only controversy came at the
tail end of the process when there was some discussion as to whether RFC 8919
/RFC 8920 Application Specific Link Attributes (ASLAs) should be used for
alternate metrics or whether the advetisements used for RSVP TE could also be
used. The consensus was to allow RFC 8919/RFC 8920 attributes to be required.

Discussion and implementation uncovered that some additional OSPF encodings
were needed for ASBR routes. This resulted in updates and second WG Last Call.
During the second WG Last Call, the discussion of the application specific
attributes resulted in Errata to both RFC 8919 and 8920:

Document Quality:

The document is of high quality with vendors and operators reviewing.
There are existing implementations of the document and three other WG documents
that augment the base document:


 Document Shepherd: Acee Lindem
 Responsible AD: John Scudder

RFC Editor Note