Re: [storm] iSCSI version descriptors
<david.black@emc.com> Tue, 08 March 2011 16:31 UTC
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From: david.black@emc.com
To: cbm@chadalapaka.com
Date: Tue, 08 Mar 2011 11:32:33 -0500
Thread-Topic: [storm] iSCSI version descriptors
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Cc: storm@ietf.org
Subject: Re: [storm] iSCSI version descriptors
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I've talked to Fred Knight (author of the iSCSI-SAM extensions draft), and the plan that seems to make the most sense is the following (which matches your views): > So at the moment, IMO, there's only need for 3 version descriptors: > > 0: no version claimed > 1: RFC 3720+5048 through RFC-consolidated > 2: RFC iSCSI-SAM We should endeavor to get reviews of the new drafts from important iSCSI implementers, and for now, I would prefer to put anything that isn't backwards compatible into the extensions draft (uses the value "2" above). I do believe that's "rough consensus" for 3 values (0, 1, 2). Thanks, --David > -----Original Message----- > From: Mallikarjun Chadalapaka [mailto:cbm@chadalapaka.com] > Sent: Monday, March 07, 2011 5:41 PM > To: 'David Harrington'; Black, David; paul_koning@Dell.com > Cc: storm@ietf.org > Subject: RE: [storm] iSCSI version descriptors > > Hi David (Harrington), > > I agree with your summary, and I wanted to get your feedback on the > following approach for the iSCSI Consolidated spec. > > Unless I am seriously forgetting something, the nature of protocol changes > in the iSCSI Consolidated spec so far fall roughly into three categories: > > 1) Removing an optional feature > 2) Removing non-mandatory negotiation options for a mandatory feature > 3) Adding an optional feature > > WG still has *not* come up with a need for the following: > 4) Adding/Changing the mandatory behavior of protocol > 5) Removing a previously mandatory feature > 6) Removing previously mandatory negotiation options for a mandatory feature > > > I do not believe changes of categories #1, #2 and #3 require a version > number bump-up - consistent with your discussion below. So at the moment, > IMO, there's only need for 3 version descriptors: > > 0: no version claimed > 1: RFC 3720+5048 through RFC-consolidated > 2: RFC iSCSI-SAM > > However, *should* the WG decide to make any changes in categories #4, #5 or > #6 down the road, I submit that (the eventual) RFC-consolidated will require > its own version number because that will be a semantic change in a mandatory > portion of the protocol. So at that point, IMO, we should switch to 4 > version descriptors: > > 0: no version claimed > 1: RFC 3720+5048 > 2: RFC-consolidated > 3: RFC iSCSI-SAM > > Comments/corrections are welcome. > > Thanks. > > Mallikarjun > > > > > -----Original Message----- > From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] On Behalf > Of David Harrington > Sent: Wednesday, December 08, 2010 7:01 AM > To: david.black@emc.com; paul_koning@Dell.com > Cc: storm@ietf.org > Subject: Re: [storm] iSCSI version descriptors > > Hi, > > Jumping in late ... > > I think compliance requirements are key here. > If you can be "compliant to version 1" if you implement mandatory feature > X AND if you do NOT implement mandatory feature X, then you don't have > a very good compliance requirement. > The purpose of a version # is to help identify the set of features that > can be > expected to be supported by OTHER implementations, to ensure > interoperability. > (obviously, if the feature was originally, and continues to be, protocol- > negotiable that's not a problem within a version#) > > I think it could be a poor engineering choice to have version 1 refer to > multiple different possible sets of features. I disagree that "Yes, using > the > same version should be a goal", if the set of features one implementation > can expect of another implementation changes; interoperability should be > the goal. You can ignore my engineering advice (I assume the WG knows the > technology better than me). But I would appreciate being educated why this > is OK. > > Interoperability is considered during IESG Evaluation > http://www.ietf.org/iesg/statement/discuss-criteria.html. If I question > the > interoperability of using the same version #, others in the IESG also > might > question this. So you should ***document in each > draft*** why using the same version # to identify the changes proposed in > that draft is OK technically from an interoperability standpoint. > > (p.s. "we've already implemented it that way from the draft" is NOT an > argument that holds much weight with the IESG). > > David Harrington > Director, IETF Transport Area > ietfdbh@comcast.net (preferred for ietf) > dbharrington@huaweisymantec.com > +1 603 828 1401 (cell) > > > -----Original Message----- > > From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] On > Behalf > > Of david.black@emc.com > > Sent: Monday, October 25, 2010 9:56 AM > > To: paul_koning@Dell.com > > Cc: storm@ietf.org > > Subject: Re: [storm] iSCSI version descriptors > > > > > For now, I believe we should say 3270/5048 and not mention > > "new consolidated draft". It doesn't > > > seem appropriate to reference a draft. If we end up being > > able to reuse the code for the > > > consolidated spec, as intended, then at the time that spec > > comes out, the description of the code > > > points would be updated to say that it applies to that RFC as > well. > > > > Yes, the specifications of the version code values need to be in terms > > of RFC numbers, not references to Internet-Drafts. > > > > Thanks, > > --David > > > > > > > -----Original Message----- > > > From: Paul Koning [mailto:paul_koning@Dell.com] > > > Sent: Friday, October 22, 2010 11:14 AM > > > To: Black, David > > > Cc: storm@ietf.org > > > Subject: Re: [storm] iSCSI version descriptors > > > > > > > > > On Oct 22, 2010, at 1:14 AM, <david.black@emc.com> > > <david.black@emc.com> wrote: > > > > > > > One more time on this issue. This is for discussion - > > it's not an announcement of a decision. > > > This is the only real issue that needs to be resolved to > > complete the new (SAM) features draft for > > > iSCSI. > > > > > > > > Reminder: we need to define a set of small positive > > integer values to describe the iSCSI version > > > starting with 0 = "no version claimed". After some private > > discussions, it appears that we need two > > > additional version values beyond 0. > > > > > > > > The first observation is that the baseline should be at > > least RFC 3720 (original iSCSI) + RFC 5048 > > > (Corrections and Clarifications). That would be version value 1. > > > > > > > > The next observation is that taking features out of the > > consolidated iSCSI draft may allow a > > > visible behavior change. RFC 3720 has this to say about > > text keys for negotiation: > > > > > > > > All keys in this document, except for the X extension > > formats, MUST > > > > be supported by iSCSI initiators and targets when used > > as specified > > > > here. If used as specified, these keys MUST NOT be > > answered with > > > > NotUnderstood. > > > > > > > > When we take out a feature in the new iSCSI consolidated > > draft, the easiest thing to do is allow a > > > NotUnderstood response to the keys that negotiate that > > feature. This should not pose a problem for > > > unimplemented features, but it would be a behavior change. > > The completely backwards-compatible > > > alternative is have the consolidated iSCSI draft list the > > keys used for removed features and > > > prohibit a NotUnderstood response to those keys (Reject > > would be an acceptable alternative > > > response). > > > > > > That sounds right. Does it cause problems for that to be > > the answer? > > > > > > > If we're careful about this, the same version value can > > apply to 3720/5048 and the consolidated > > > iSCSI draft. I'd suggest that we be careful, and the > > details of how can be worked out as we > > > finalize the consolidated draft - I think we should have at > > least one more round of looking at > > > features to remove. > > > > > > Yes, using the same version should be a goal. > > > > > > > After that, we'll need a version value for the new (SAM) > > features draft additions. The result > > > would be 3 version values: > > > > 0 = no version claimed > > > > 1 = 3720/5048 or new consolidated draft > > > > 2 = (3720/5048 or new consolidated draft) + SAM 4/5 > > features from the SAM draft. > > > > > > I assume these numbers will be handled by IANA, so they'll > > need an IANA Considerations section > > > spelling out how. > > > > > > For now, I believe we should say 3270/5048 and not mention > > "new consolidated draft". It doesn't > > > seem appropriate to reference a draft. If we end up being > > able to reuse the code for the > > > consolidated spec, as intended, then at the time that spec > > comes out, the description of the code > > > points would be updated to say that it applies to that RFC as > well. > > > > > > For the SAM draft, can we reference a specific draft? I > > think it's quite absurd that drafts even > > > have standard status in the first place, but given that > > they do, we need to be precise about which > > > document we're talking about. If we say "draft 2010/10/34" > > now, and then a followup draft comes out > > > for which the same code point is appropriate, we'd update > > the description of the code point to list > > > that one as well. But we can't leave it unstated. > > > > > > paul > > > > > > > _______________________________________________ > > storm mailing list > > storm@ietf.org > > https://www.ietf.org/mailman/listinfo/storm > > > > _______________________________________________ > storm mailing list > storm@ietf.org > https://www.ietf.org/mailman/listinfo/storm >
- Re: [storm] iSCSI version descriptors Paul Koning
- [storm] iSCSI version descriptors david.black
- Re: [storm] iSCSI version descriptors Knight, Frederick
- Re: [storm] iSCSI version descriptors david.black
- Re: [storm] iSCSI version descriptors david.black
- Re: [storm] iSCSI version descriptors David Harrington
- Re: [storm] iSCSI version descriptors Mallikarjun Chadalapaka
- Re: [storm] iSCSI version descriptors Mallikarjun Chadalapaka
- Re: [storm] iSCSI version descriptors david.black
- Re: [storm] iSCSI version descriptors david.black
- Re: [storm] iSCSI version descriptors Mallikarjun Chadalapaka
- Re: [storm] iSCSI version descriptors david.black