Re: [storm] iSCSI version descriptors
<david.black@emc.com> Wed, 09 March 2011 23:07 UTC
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From: david.black@emc.com
To: cbm@chadalapaka.com, storm@ietf.org
Date: Wed, 09 Mar 2011 18:08:16 -0500
Thread-Topic: [storm] iSCSI version descriptors
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Subject: Re: [storm] iSCSI version descriptors
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Yes, we're in agreement, violent or otherwise ;-). Thanks, --David > -----Original Message----- > From: Mallikarjun Chadalapaka [mailto:cbm@chadalapaka.com] > Sent: Wednesday, March 09, 2011 3:51 PM > To: Black, David; storm@ietf.org > Subject: RE: [storm] iSCSI version descriptors > > David, > > I believe we are in general agreement. Just a couple of comments. > > > My design preference is to recommend (SHOULD) a "Reject" value response, > > which is allowed by RFC 3720 and has the additional virtue of carrying a > > "What on earth do you think you're doing?" implication back to the clue- > > impaired implementation that tried to use the obsolete feature. > > I am fine with: SHOULD "Reject", MAY reply with "No", MUST NOT reply with a > "NotUnderstood". > > I have re-read the relevant RFC 3720 text and the formulation above is > compliant with its semantics. > > > That covers half the cases - new initiator with new or old responder. With > > an old initiator, it is possible that obsolete options are offered. If obsolete > > options are offered in combination with one or more supported options, > > everything should work fine. If obsolete options are the only ones offered, > > "Reject" is an appropriate response. > > We may be in violent agreement, :) I agree with what you say, except I will > point out that the relevant list negotiation semantics are already in RFC > 3720 (and by extension, already in Consolidated draft). So nothing new > needs to be specified (which is what I meant by "nothing special"), consider > the following text in section 5.2.1 of RFC 3720: > > If an acceptor does not understand any particular value in a list, it > MUST ignore it. If an acceptor does not support, does not > understand, or is not allowed to use any of the proposed options with > a specific originator, it may use the constant "Reject" or terminate > the negotiation. > > Thanks. > > Mallikarjun > > > > > >-----Original Message----- > > From: david.black@emc.com [mailto:david.black@emc.com] > > Sent: Tuesday, March 08, 2011 8:22 AM > > To: cbm@chadalapaka.com; storm@ietf.org > > Subject: RE: [storm] iSCSI version descriptors > > > > Mallikarjun, > > > > While I think your option 1) is ok: > > > > > 1) When a feature is completely obsoleted (e.g. markers) relative to > > > 3720, iSCSI consolidated spec requires that the corresponding keys be > > > negotiated to "No" (e.g. OFMarker=No). > > > > My design preference is to recommend (SHOULD) a "Reject" value response, > > which is allowed by RFC 3720 and has the additional virtue of carrying a > > "What on earth do you think you're doing?" implication back to the clue- > > impaired implementation that tried to use the obsolete feature. In any > > case, we're in clear agreement that a "NotUnderstood" response has to be > > prohibited. > > > > > 2) When a feature *option* is obsoleted (e.g. SPKM1 & SPKM2 for > > AuthMethod), > > > the spec does nothing special. The existing iSCSI negotiation > semantics > > > are comprehensive enough that two spec-compliant implementations will > > > negotiate to the correct result because the obsoleted options for that > > > feature are not offered as negotiables. > > > > That covers half the cases - new initiator with new or old responder. > With > > an old initiator, it is possible that obsolete options are offered. If > obsolete > > options are offered in combination with one or more supported options, > > everything should work fine. If obsolete options are the only ones > offered, > > "Reject" is an appropriate response. > > > > Thanks, > > --David > > > > > -----Original Message----- > > > From: Mallikarjun Chadalapaka [mailto:cbm@chadalapaka.com] > > > Sent: Monday, March 07, 2011 5:13 PM > > > To: Black, David; storm@ietf.org > > > Subject: RE: [storm] iSCSI version descriptors > > > > > > David, > > > > > > In trying to determine what if any text needs to change in the > > > consolidated spec after this discussion, I did a re-reading of this > whole > > thread - up to > > > DavidH's most recent note. I stumbled on the following: > > > > > > > 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). > > > > > > I do not believe the consolidated spec needs to change the current > > > negotiation semantics. I suggest a third option: > > > 1) When a feature is completely obsoleted (e.g. markers) relative to > > > 3720, iSCSI consolidated spec requires that the corresponding keys be > > > negotiated to "No" (e.g. OFMarker=No). > > > > > > 2) When a feature *option* is obsoleted (e.g. SPKM1 & SPKM2 for > > AuthMethod), > > > the spec does nothing special. The existing iSCSI negotiation > semantics > > > are comprehensive enough that two spec-compliant implementations will > > > negotiate to the correct result because the obsoleted options for that > > > feature are not offered as negotiables. > > > > > > > > > This should minimize the core protocol changes, and related impacts to > > > existing interop tests. > > > > > > Comments are welcome. With the fast-approaching Prague deadline, I > > > will go ahead with the spec'ing this option if I don't hear any > > > disagreement on this by this Wednesday. > > > > > > Thanks. > > > > > > Mallikarjun > > > > > > > > > > > > > > > -----Original Message----- > > > From: storm-bounces@ietf.org [mailto:storm-bounces@ietf.org] On > > Behalf > > > Of david.black@emc.com > > > Sent: Thursday, October 21, 2010 10:15 PM > > > To: storm@ietf.org > > > Subject: [storm] iSCSI version descriptors > > > > > > 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). > > > > > > 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. > > > > > > 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. > > > > > > Comments? > > > > > > The SAM 4/5 features draft will expire while draft submission is > > > closed for > > > the Beijing meeting - if we can resolve this issue, the next version > > > of that > > > draft could be submitted shortly after draft submission opens again, > and > > > would probably go to WG Last Call shortly thereafter. > > > > > > Thanks, > > > --David > > > ---------------------------------------------------- > > > David L. Black, Distinguished Engineer > > > EMC Corporation, 176 South St., Hopkinton, MA 01748 > > > +1 (508) 293-7953 FAX: +1 (508) 293-7786 > > > david.black@emc.com Mobile: +1 (978) 394-7754 > > > ---------------------------------------------------- > > > > > > _______________________________________________ > > > 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