Hi Ted, Thanks for the review. Please see inline. Regards Sri > -----Original Message----- > From: ietf-bounces@xxxxxxxx [mailto:ietf-bounces@xxxxxxxx] On > Behalf Of Ted Hardie > Sent: Wednesday, February 13, 2008 5:01 PM > To: iesg@xxxxxxxx; ietf@xxxxxxxx > Subject: Re: Last Call on draft-ietf-netlmm-proxymip6 > > Summary: One issue needs resolution. > > First, let me start by saying that -09, which was put out for > Last Call, was a substantial > improvement over the -08. I normally read Last Call > documents using a diff tool, > and the number of really solid additions in this update was > quite high. I was a bit > surprised, given the extent of the new text, that there was > no WG last call, but > I assume that the WG is reviewing the changes in parallel. > I assume that the issuance > of -10, which came out during the last call, was a response > to one or more reviews > from the WG or solicited experts. > > To call out one particular improvement, I found the update's > language around > multi-homing much clearer, and I believe the risk of > assignment of the same > address to multiple interfaces is much reduced in this > version. Given the > potential consequences (watching your stack scream "I'm > melting! I'm melting!" > as someone entertainingly put it), that's a really good thing. > > There are still some opportunities for editorial update, and > I hope that as > the IESG enters its discussions that some of those are > targets for resolution. > I'd particularly like to see even more clear light on the > description in > bullet 4 of Section 6.9.1.1, as "predictably knows" is not as clean as > it might be. (The current sentence is: "The Handoff > Indicator field MUST be set to > value 1 (Attachment over a new interface), if the mobile > access gateway predictably > knows that the mobile node's current attachment to the > network over this > interface is not as a result of an handoff of an existing > mobility session (over > the same interface or through a different interface), but as > a result of an > attachment over a new interface. "). But that is really a > language clarity > problem, at least I hope, at this point. > There are clearly specified rules as when a mobile access gateway is allowed to choose a specific handoff hint. These rules are clearly layed out and there was a quite of focus in the AD review on this aspect. It is not the intent of the document to allow the mobility entities to specify a given handoff hint, say HI=Handoff between MAG's, unless it is absolutely sure its the same session that is being handed off. Probably there needs to be better choice of the words in the above rule. It is a language clarity issue. We will rephrase it. > The big issue that remains is actually one that starts from > the scope creep. > > I was on the IESG during the period when this charter was > approved, and it > was clear at the time that some of the limitations being put > in were intended > to focus NETLMM on cases where nodes were re-associating at > layer 2 with the > same network. The charter says, for example: "The protocol > will not attempt > to hide handover between two separate interfaces on the > mobile node.". > This document (and, as I understand it, the working group > discussion for some time) > has gone beyond that initial scope. A good portion of this > document's complexity > is because it does handle the multi-interface case. While it > would have been nice > to have the charter updated to state the new scope, I don't > personally have a > problem with the scope. I am concerned, however, that the > design constraints > changed with that new scope and that other parts of the > charter are limiting > folks' understandings of what can be done here, when those > restraints are really > salient for the single layer 2 initial scope. > > To put it simply, given the inter-technology handoff, > signalling from the mobile node > to the network is one of the clearest and most likely to be > interoperable ways to achieve > the correct behavior in some of the base cases. At the > moment, because the mechanisms > for setting the handoff indicator do not necessarily involve > the mobile node (and are > appear to be below IP where between the mobile node and the > networ), a mobile node with multiple interfaces will not > always be able to signal that it desires handoff or > prefers multihoming. The document is now clear that in that > case it gets > multihoming. That's a tremendous advance over the previous > state. But the really > big win here would be to enable the signaling . As it > stands, the operations are based > on the handoff indicator provided by the MAG, but the > document does not provide > any information on how the MAG will know this information. > There certainly will > be cases where a network architecture will allow the MAG to > use layer 2 indicators > or other mechanisms, but there will also be cases where that > set of mechanisms > is inconsistently available. Adding the higher-layer > signalling makes this a complete solution. > > I'm concerned that sending the document out in its current > state will either require > a quick re-spin at PS to enable this once the issues arise in > deployment or that some of > the contexts in which this is intended to be used will work > around the problem in ways which will hinder an > interoperable, long-term deployment. > > I am very conscious, however, that there is considerable time > pressure on this > document. I propose the following as a way forward which > should not add any significant delay. > > 1) Add an explicit, normative reference to > draft-netlmm-mn-ar (which would > need to be revived) as the basis for a forthcoming above-IP > signalling mechanism, > using an RFC-Editor's note. > > 2) Put draft-netlmm-mn-ar on the standards track, but make an > explicit > downref statement for this document to the internet-draft. > This would allow > this document to progress without delay, but provide a > reference for those who > will be deploying this in contexts which do not have the same > highly-structured > network management of the networks for which this is urgent. When > draft-netlmm-mn-ar is published, it would be available, of > course, to both network types. > > 3) Go ahead with IESG processing on this document on the > basis of the existing Last Call > date, with the understand that the IESG would reconsider only > if the second Last Call > with the explicit downref raised new issues. IESG > consideration prior to the end of a Last Call already occurs > in some cases, and it certainly could be used in this case to meet the > time pressures. > > > I'm aware that the charter states that there should be no > signalling required > between the mobile and the network. In the context of the > original design scope, > that should have been read quite strictly. In the context of > the current design scope, > I believe we have to distinguish between making something > required and setting > a standard way of handling something in the inter-technology > case. I do not believe > that adding this normative reference would make it required. > It would simply > show how the IETF intended to meet the need for an > interoperable mechanism > for signalling where the mobile node had the capability and > interest. Where it did > not, the basic mechanisms in this draft would suffice. > > I understand that this has been an active, and at times > contentious, area of discussion, > and I do not want this last call comment to fan any old > flames. As an APPs guy, trust > that I'm in favor of pretty much anything that reduces the > need for updated IP addresses > and all the concomitant pain. I also see us about to miss > an opportunity here, by > setting out a toolkit that is missing a critical tool. I > don't believe the time pressures > here should or need to stop us from building the full > toolkit, even if the first shipment > of toolboxes goes out simply with the right shape cut out, to > be filled later. > > regards, > Ted Hardie > _______________________________________________ > Ietf mailing list > Ietf@xxxxxxxx > http://www.ietf.org/mailman/listinfo/ietf > _______________________________________________ Ietf@xxxxxxxx http://www.ietf.org/mailman/listinfo/ietf