Reviewer: Victor Kuarsingh
Review Result: Ready

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.

In short, the document and updated specifications to be applied to RFC4271 (BGP-4) to introduce a ‘SendHoldTimer’ seems well targeted, well defined and generally desirable as a feature.  It was good to see multiple early implementations across OpenBGPD, FRR, neo-bgp and BIRD as noted in Appendix A.  

I do have a non-blocking comment for the authors which should be taken as a question of interest from an operational perspective.  Under the operational considerations section, I did see it mention considerations such as sending a ‘send hold timer expired’ code irrespective if the remote peer may be able to process (that’s fine/good, what I would expect to see in such a section). 

However, what I did not see, and may be available as output from testing on the early implementations and inter-op, is if there are conditions where the invoking of the timer expired by the local peer creates an unneeded operational event (e.g. for example the remote peer may seem to no be processing updates, but may actually be). So, in such a case, although this feature is generally desirable, there may be a condition where it is not desirable or optimal.  I don’t see this is a big deal per se, but wondering if there were such observations in test (either yes, but not significant or no, we did not detect such a situation).

Thanks, 

Victor K