I am the assigned Gen-ART reviewer for this draft. The General Area Review Team (Gen-ART) reviews all IETF documents being processed by the IESG for the IETF Chair. Please treat these comments just like any other last call comments. Apologies for the slightly late review - I was stricken by a stomach bug. For more information, please see the FAQ at < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>. Document: draft-ietf-l2tpext-sbfd-discriminator-03.txt Reviewer: Elwyn Davies Review Date: 2016/04/10 IETF LC End Date: 2016/04/05 IESG Telechat date: (if known) - Summary: Almost ready. There are a number of acronyms that need expansion and I am unclear how an implementation of S-BFD getting its discriminators via L2TPv3 would know what entities the advertised discriminators (whether one or many) should be associated with. This probably just needs a single sentence to sort it out, but I found the existing wording to be either inappropriate or just plain wrong. Nearly Major Issue: Question: The format allows multiple discriminators to be sent in one message. Looking at the S-BFD base draft (s3), it is implied that if a S-BFD module is dealing with multiple discriminators they would be associated with multiple different entities. How would the receiver know what entity each of the discriminators was supposed to be associated with? It seems to me that the receiver would want to know this but I may not have understood what is going on here. I guess one way would be to use a part of the discriminator bit pattern but I don't know if this might make it more difficult to achieve uniqueness in a domain. Alternatively a purpose provided field could be sent in addition to each discriminator, or different AVP IDs used for well-known purposes. The sentence at the end of para 4 of s2.1: When multiple S-BFD discriminators are advertised, the mechanism to choose a subset of specific discriminator(s) is out of scope for this document. may be associated with this question but I am not sure (1) which end is supposed to be choosing - is the Initiator choosing which to advertise or the Responder choosing which to 'do something with', and (2) it seems to me that the L2TPv3 receiver or its associated S-BFD module would be deciding on some well-defined basis which entities were associated with which designator rather than just making an arbitrary choice. I suggest that a sentence indicating how the association of discriminators to entities is done (or even that it needs to be done but how it is done is out of scope) needs to be added, and the sentence above needs to be clarified or subsumed in this new part (unless either of the more draconian alternatives suggested above is thought to be appropriate). Minor issues: None Nits/editorial comments: Abstract: I'm afraid you are going to have expand the acronyms AVP, L2TP and BFD here. References to RFC 5880 and the new S-BFD draft RFC would also be helpful - in the form "(RFC 5880, I-D.ietf-bfd-seamless-base)". s1.1: The L2TP message names used in s2.1 and elsewhere (ICRQ, ICRP, OCRQ, OCRP) need to be expanded - here would be as good as anywhere. s2.1: Need to expand AVP and ID.