[mif] Adrian Farrel's No Objection on draft-ietf-mif-mpvd-arch-10: (with COMMENT)
"Adrian Farrel" <adrian@olddog.co.uk> Thu, 19 February 2015 14:19 UTC
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From: Adrian Farrel <adrian@olddog.co.uk>
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Date: Thu, 19 Feb 2015 06:19:36 -0800
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Cc: draft-ietf-mif-mpvd-arch.all@ietf.org, mif@ietf.org, denghui02@hotmail.com, mif-chairs@ietf.org
Subject: [mif] Adrian Farrel's No Objection on draft-ietf-mif-mpvd-arch-10: (with COMMENT)
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Adrian Farrel has entered the following ballot position for draft-ietf-mif-mpvd-arch-10: No Objection When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to http://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: http://datatracker.ietf.org/doc/draft-ietf-mif-mpvd-arch/ ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- I have No Objection to the publication of this document. Here are some comments that you can take or leave in discussion with your AD. Some of these Comments and nits come from a "training review" by Alvaro. --- I think you correctly avoid the use of 2119 language. You can delete the boilerplate and reference. --- I think you are talking about dual homed devices rather than dual homed networks. More precisely, the "node" that is dual homed is not a router but is a host. Possibly, you are extending to a dual homed home gateway. But I think (I hope) you are not intnding to cover dual homed ASBRs or ABRs. And you are not (I hope) covering dual-homed CPEs such as might provide access to a substantial enterprise network. I think that this would benefit from more explanation of scope in the document. In practice, you are discussing making connectivity choices rather than routing choices. If I have this wrong, please tell me and I can worry about whether this should have been a Discuss :-) [BTW Section 4 is great, but it addresses my specific concerns by example rather than statement.] --- The document uses "policy" a bit like a unicorn. Of course, there is a fine tradition of saying "the node will apply locally configured policy" but you have an opportunity to be much more specific and so far more helpful for protocol developers and for implementers. Policies are easy to write in pseduorcode, and I think you know the core set of policies you expect to see supported. So you could supply some guidance. --- I also think there is a problem with how policy is expected to be configured. The "nodes" you are talking to are (I think) end-system hosts rather than routers (see my prvious) and many of these will be relatively dumb devices and/or have relatively dumb users. These users will not be capable of making more than very basic policy decisions and their choics will need to be presented in different terms to the choices that the device itself makes. This would benefit from discussion because the policy model will need more work. --- Some references to other parts of the document are missing. 2.1 discusses about the possibility of using DHCP to carry information about the PvD, but there's no reference to the later section that talks about the same topic. 2.3 talks a little about authentication, but no reference to the trust section later. --- Section 2.1 Link-specific and / or vendor-proprietary mechanisms for the discovery of PvD information (differing from IETF-defined mechanisms) can be used by nodes either separate from, or in conjunction with, IETF-defined mechanisms; providing they allow the discovery of the . necessary elements of the PvD(s). In all cases, nodes must by default ensure that the lifetime of all dynamically discovered PvD configuration is appropriately limited by relevant events. For example, if an interface media state change is indicated, previously discovered information relevant to that interface may no longer be valid and so need to be confirmed or re- Discovered. The first paragraph seems to be superfluous to me (of course I can use proprietary mechanisms!), but then the second has (what should be) a normative directive: "must ensure appropriate lifetime". But, I tend to see "appropriate" and "relevant" as red flags! Why are you not able to give firmer directives? --- Section 2.4 PvD ID is a value that is, or has a high probability of being globally unique. If it's capable of not being unique, you have to handle conflict. If you have to handle conflict, it becomes less important that the probability of being unique is high. Maybe... If two PvDs have the same ID, this conflict must be detected and resolved. Using a mechanism that selects values that are more likely to be unique has the benefit of more rapid convergence and no need to execute the conflict resolution mechanism. And please be careful with "globally unique". Is "global" really that or is it constrained? --- Section 3.3 has references to what seems to be possible solutions or just other work. I think that just saying that "any new mechanisms should consider co-existence with deployed mechanisms" is enough. --- Section 5.2.3 introduces "PvD-aware applications". This is not clearly defined. Maybe this is just another example of a policy that is not defined in the document.
- [mif] Adrian Farrel's No Objection on draft-ietf-… Adrian Farrel
- Re: [mif] Adrian Farrel's No Objection on draft-i… Ted Lemon