Last Call Review of draft-ietf-ospf-ospfv2-hbit-10
review-ietf-ospf-ospfv2-hbit-10-opsdir-lc-chown-2019-11-07-00

Request Review of draft-ietf-ospf-ospfv2-hbit
Requested rev. no specific revision (document currently at 10)
Type Last Call Review
Team Ops Directorate (opsdir)
Deadline 2019-11-07
Requested 2019-10-24
Authors Keyur Patel, Padma Pillay-Esnault, Manish Bhardwaj, Serpil Bayraktar
Draft last updated 2019-11-07
Completed reviews Rtgdir Last Call review of -09 by He Jia (diff)
Genart Last Call review of -10 by Mohit Sethi
Tsvart Last Call review of -10 by Kyle Rose
Opsdir Last Call review of -10 by Tim Chown
Assignment Reviewer Tim Chown
State Completed
Review review-ietf-ospf-ospfv2-hbit-10-opsdir-lc-chown-2019-11-07
Posted at https://mailarchive.ietf.org/arch/msg/ops-dir/P88EhPs8chRhr2vcmpeE6CkK5JE
Reviewed rev. 10
Review result Has Nits
Review completed: 2019-11-07

Review
review-ietf-ospf-ospfv2-hbit-10-opsdir-lc-chown-2019-11-07

I have reviewed this document as part of the Operational directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written with the intent of improving the operational aspects of the IETF drafts. Comments that are not addressed in last call may be included in AD reviews during the IESG review.  Document editors and WG chairs should treat these comments just like any other last call comments.

The document describes a mechanism by which a node running OSPFv2 can repel transit traffic if it is on the shortest path (and an alternative path exists - though this is not wholly clear in the document). It defines a Host-bit (H-bit) that allows the router to advertise that it is not a transit router, and it describes the changes needed to support the H-bit within a domain, and mitigations against potential routing loops.

General comments:

Should the document also state that it updates RFC 2328?

I think the document could be clearer on the behaviour when the H-bit and MaxLinkMetric are used when there is only one path available, i.e. there is no redundant / alternative path.  Section 4 of RFC 6987 implies that if there is only one path the router can still be used as a transit router, by the nature of the definition of MaxLinkMetric.  The document has 3 or 4 places where it hints at behaviour, but I think it could be more explicit.

It may be worth explicitly stating that OSPFv3 is not mentioned due to it having an R-bit defined for indicating whether a node/router can be used for transit traffic (see Sections 2.7 and A.2 of RFC 5340).

The reasons given in Section 1 for the need for the H-bit are different to those given in Section 1 of RFC 6987 for the capability.  Should these be more consistent?   Also, the document later mentions “a router being gracefully isolated” as a reason, but this is not mentioned in Section 1.

Nits:

In the abstract:
Change
“This document defines a bit (Host-bit)”
to
“This document defines a Host bit (H-bit)”
for consistency
And “is a non-transit router.”” - remove the spurious “.

Section 8:
Where it says “beyond those already known in OSPF”, say OSPFv2.