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Last Call Review of draft-ietf-lsr-flex-algo-12

Request Review of draft-ietf-lsr-flex-algo
Requested revision No specific revision (document currently at 26)
Type Last Call Review
Team Routing Area Directorate (rtgdir)
Deadline 2020-10-16
Requested 2020-10-01
Requested by Acee Lindem
Authors Peter Psenak , Shraddha Hegde , Clarence Filsfils , Ketan Talaulikar , Arkadiy Gulko
I-D last updated 2020-10-18
Completed reviews Rtgdir Last Call review of -12 by Eric Gray (diff)
Rtgdir Last Call review of -18 by Henning Rogge (diff)
Opsdir Last Call review of -23 by Linda Dunbar (diff)
Secdir Last Call review of -23 by Charlie Kaufman (diff)
Genart Last Call review of -23 by Dan Romascanu (diff)
Opsdir Telechat review of -25 by Linda Dunbar (diff)
Last request was for early review. Please cancel previous.
Assignment Reviewer Eric Gray
State Completed
Request Last Call review on draft-ietf-lsr-flex-algo by Routing Area Directorate Assigned
Posted at
Reviewed revision 12 (document currently at 26)
Result Has nits
Completed 2020-10-16

I have been selected as the Routing Directorate reviewer for this draft. The
Routing Directorate seeks to review all routing or routing-related drafts as
they pass through IETF last call and IESG review, and sometimes on special
request. The purpose of the review is to provide assistance to the Routing ADs.
For more information about the Routing Directorate, please see

Although these comments are primarily for the use of the Routing ADs, it would
be helpful if you could consider them along with any other IETF Last Call
comments that you receive, and strive to resolve them through discussion or by
updating the draft.

Document: draft-ietf-lsr-flex-algo-12.txt

Reviewer: Eric Gray

Review Date: 16 October, 2020

IETF LC End Date: Unknown

Intended Status: Standards Track


This document is well organized, relatively easy to read, and probably ready
for publication, but has one potential minor issue and a very small number of
NITs that might be considered prior to publication.

Major Issues:


Minor Issues:

The statement in section 15 (Backward Compatibility) - "This extension brings
no new backward compatibility issues" - seems somewhat flip.

I suspect that a tiny bit of analysis would not hurt.

The extensions in this draft are clearly intended to work in an environment
where routers that _do_not_ support these extensions are also deployed, but
apparently relies on configuration of those routers that _do_ support the
extensions to address this.

That seems correct.

From my reading of the draft (which I have not closely followed for its entire
development), while it introduces at least one new TLV, the OSPF routing
protocol has well defined handling for TLVs that are not understood - hence the
introduction of one or more new TLVs should not present a problem in OSPF.

Obviously Sub-TLVs of the new OSPF TLV type will not introduce compatibility

I assume (but do not actually know) that a similar situation exists for the new
ISIS FAD Sub-TLV of the existing TLV Type 242 - i.e. - ISIS presumably has well
defined handling for sub-TLVs (of at least type 242) that are not recognized. 
If so, than the new Sub-TLV types defined are also not an issue.

Shouldn't this section say something along these lines?  I suspect that it
would be more helpful if verifying the content of the "considerations" sections
were not left as an exercise for the reader.  😊


In the Introduction, the phrase "must often be replaced" seems very slightly
problematic (especially given this is a standards track RFC wanna-be).  Would
it be better to say "is often replaced" instead?

In section 17.1.2 and 17.2 - '... a "Interior Gateway ...' should probably be
'... an "Interior Gateway ..." in both cases.