Re: [storm] iSCSI and Unicode (newprep BOF)
<Black_David@emc.com> Tue, 23 March 2010 22:28 UTC
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Thread-Topic: [storm] iSCSI and Unicode (newprep BOF)
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From: Black_David@emc.com
To: Paul_Koning@Dell.com, storm@ietf.org
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Subject: Re: [storm] iSCSI and Unicode (newprep BOF)
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Paul, I concur with your reasoning, example and strong desire for "MUST". The newprep BOF is starting now - I'll report on results. Thanks, --David > -----Original Message----- > From: Paul Koning [mailto:Paul_Koning@Dell.com] > Sent: Tuesday, March 23, 2010 3:34 PM > To: Black, David; storm@ietf.org > Subject: RE: [storm] iSCSI and Unicode (newprep BOF) > > > > Re "Any update SHOULD be backward compatible with RFC 3722" -- I don't understand the "SHOULD". The > > > obvious word is "MUST". More precisely -- and maybe this is where the "SHOULD" came in? -- an IQN > > > that was legal under RFC 3722 must still be legal, and two names that under the old rules were > > > considered different must still be different. > > > > The "SHOULD" is there to a significant extent so that I can plead "I'm > > not a Unicode expert" ;-). At the iSCSI protocol level, I expect > > everything to be backwards-compatible because iSCSI names aren't > > checked for stringprep compliance on login (the iSCSI name string > > comparison for equality is basically opaque wrt Unicode issues). > > > > Moving up to the iSCSI name input level (human involvement), it is > > possible that things have changed in Unicode so that the same Unicode > > input string will need to map to a different newprep output string vs. > > stringprep output string for reasons involving Unicode. If that's the > > case (and especially if some previously valid inputs have to be > > prohibited), then everything will need to be carefully explained and > > documented with advice on how to cope ... but I hesitate to lead with a > > "MUST", as the IDN folks have much deeper knowledge of what's going on > > here, what needed to be done with Unicode domain names, and why (a > > "MUST" risks freezing iSCSI @ an old version of Unicode). > > If so, then so be it. I really do want MUST here. > > Consider a simple example. To avoid getting deep into Unicode, let's > use an ASCII analogy. Let's say the old rule is that names are prepped > by tolower() and the new rule says they are prepped by toupper(). And > let's assume that this operation is done only when the target name is > mentioned in some management UI as you suggested. (I think we might do > it also at login, but it doesn't actually affect the outcome of the > example in a way that matters.) > > Ok, so in the old version, the admin asked me to create target Foo, > which I prepped to "foo", so we now have that target. Next the user > tells the initiator to log in to Foo and the initiator preps that to > "foo" which comes across the login protocol exchange and all is well. > > Now we go to the new rule. The admin sets up a new initiator, and tell > it to connect to Foo. That initiator UI preps the string, which results > in "FOO". That comes across in the login. We do binary compare at > login time, so the result of the login operation is "no such target". > > You might think you can cure this problem by re-prepping all previously > stored names with the new rules. That works ONLY if (a) all previously > valid names are still valid, (b) all previously distinct names are still > distinct. > > We clearly can't have a case where an existing iSCSI target becomes > inaccessible because of new name rules; this is my reason for saying > that any newprep changes MUST not have such an effect. > > paul >
- [storm] iSCSI and Unicode (newprep BOF) Black_David
- Re: [storm] iSCSI and Unicode (newprep BOF) Mark Bakke (mbakke)
- Re: [storm] iSCSI and Unicode (newprep BOF) Paul Koning
- Re: [storm] iSCSI and Unicode (newprep BOF) Black_David
- Re: [storm] iSCSI and Unicode (newprep BOF) Paul Koning
- Re: [storm] iSCSI and Unicode (newprep BOF) Black_David
- Re: [storm] iSCSI and Unicode (newprep BOF) Peter Saint-Andre
- Re: [storm] iSCSI and Unicode (newprep BOF) Black_David
- Re: [storm] iSCSI and Unicode (newprep BOF) Julian Satran
- Re: [storm] iSCSI and Unicode (newprep BOF) Paul Koning
- Re: [storm] iSCSI and Unicode (newprep BOF) Julian Satran
- Re: [storm] iSCSI and Unicode (newprep BOF) Black_David
- Re: [storm] iSCSI and Unicode (newprep BOF) Paul Koning