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    RE: iSCSI: Case-sensitivity in iSCSI names



    Have room for one more on that wagon..? Sounds like a good way to go.
    
    
    -------------------------------------------------------
     Shawn Carl Erickson           (805) 883-4319 [Telnet]
     Hewlett Packard Company         OV NSSO Joint Venture
      Storage Resource Management R&D Lab (Santa Barbara)
    -------------------------------------------------------
                <http://ecardfile.com/id/shawnce>
    -------------------------------------------------------
    
    
    > -----Original Message-----
    > From: John Hufferd [mailto:hufferd@us.ibm.com]
    > Sent: Tuesday, July 24, 2001 3:34 PM
    > To: Jim Hafner
    > Cc: ips@ece.cmu.edu
    > Subject: Re: iSCSI: Case-sensitivity in iSCSI names
    > 
    > 
    > 
    > I want to jump on this bandwagon too.  This seems to be 
    > exactly the right
    > approach.
    > 
    > .
    > .
    > .
    > John L. Hufferd
    > Senior Technical Staff Member (STSM)
    > IBM/SSG San Jose Ca
    > Main Office (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
    > Home Office (408) 997-6136
    > Internet address: hufferd@us.ibm.com
    > 
    > 
    > Jim Hafner/Almaden/IBM@IBMUS@ece.cmu.edu on 07/24/2001 02:24:06 PM
    > 
    > Sent by:  owner-ips@ece.cmu.edu
    > 
    > 
    > To:   ips@ece.cmu.edu
    > cc:
    > Subject:  Re: iSCSI: Case-sensitivity in iSCSI names
    > 
    > 
    > 
    > 
    > Mark and Bob,
    > 
    > This looks like exactly what we want.  In short, whatever 
    > rules should be
    > applied to domain names should be applied to iSCSI names.  
    > This seems to be
    > a very clean way to express that principle.
    > 
    > Thanks Bob!
    > 
    > Jim Hafner
    > 
    > 
    > Mark Bakke <mbakke@cisco.com>@ece.cmu.edu on 07-24-2001 12:27:16 PM
    > 
    > Sent by:  owner-ips@ece.cmu.edu
    > 
    > 
    > To:   Robert Snively <rsnively@Brocade.COM>
    > cc:   IPS <ips@ece.cmu.edu>
    > Subject:  Re: iSCSI: Case-sensitivity in iSCSI names
    > 
    > 
    > 
    > 
    > Bob-
    > 
    > Very useful comments.  I had not seen the idn-nameprep draft, and
    > am somewhat surprised that I missed it when I was looking for this
    > stuff before.  I just read through nameprep-05, and it looks like
    > the sort of thing that I had in mind by recommending that names
    > be generated in lower case of whatever character set was being used.
    > 
    > Anyway, if this is to be used for domain names, we ought to use it,
    > too.  Any idea when it will be an RFC?
    > 
    > More comments below.
    > 
    > --
    > Mark
    > 
    > Robert Snively wrote:
    > >
    > > I am concerned about this approach for two reasons.
    > >
    > > 1)  Name server programs do not allow case insensitivity.
    > >
    > > If I understand correctly from my admittedly incomplete experience
    > > in this area, the names must be entered through an appropriate
    > > application.  Different systems and applications allowed to enter
    > > such names may actually create different encodings for each 
    > character
    > > that is represented. As one example, three separate encodings are
    > > identified in draft-duerst-i18n-norm-04.txt for the character
    > > LATIN CAPITAL LETTER A WITH RING ABOVE.  Thus, what you typed
    > > into the system would not be able to be found in a "case-sensitive"
    > > international environment unless the original name happened to be
    > > made by a program that used the same encoding, even though the
    > > characters look identical.  The solution being proposed is that
    > > all names go through a "NAMEPREP" process described in
    > > draft-ietf-idn-nameprep-05.txt.  That process maps all
    > > permitted code points to a normalized code point, including
    > > forcing the names to be case insensitive.  That is (again if
    > > I understand it correctly), the character "B" will be mapped to
    > > the character "b" before it is ever used by a name service program.
    > > Thus, we are fooling ourselves if we expect a B to be differentiated
    > > from a b by any compliant name server.
    > 
    > I was hoping that nobody would generate both "B" and "b" anyway, but
    > the definition in NAMEPREP is much better.
    > 
    > > 2)  Name registration will become painful (and perhaps expensive)
    > >
    > > If I understand correctly how domain names are registered, they
    > > are presently registered by the case-insensitive character
    > > string.  If I make the name of a SCSI device case sensitive, it
    > > implies that a name must now be registered in all its case sensitive
    > > variations.  Thus a company like Cisco must register a minimum
    > > of three variations of the name, Cisco, CISCO, and cisco to be
    > > reasonably assured of correct resolution to the domain.  This
    > > strikes me as a significant complication of the registration
    > > process.
    > 
    > OK
    > 
    > > Assuming I have understood this environment correctly, I see two
    > > possible solutions to these problems.
    > >
    > > 1)  My original thought was to make the names using manufacturer
    > >     established invariant binary values, using an appropriate
    > >     World-Wide-Name like the EUI-64.  Those have the benefit
    > >     of being internationalized to all countries that use
    > >     binary or hexadecimal numbers.  They have the inconvenience
    > >     of requiring an installation process that maps them to
    > >     a locally assigned user-friendly name, but those installation
    > >     processes would normally be automated anyway.  The user-friendly
    > >     name would probably be the domain name of the local network
    > >     modified by appropriate locally assigned variables.
    > >
    > >     This is in some sense like the Ethernet MAC names which are
    > >     world-wide unique invariant formats that are mapped to
    > >     convenient IP addresses and domain names.
    > 
    > This is allowed in iSCSI names by using the "eui" format, for
    > those who can use EUI-64.
    > 
    > > 2)  Since my original thought has long ago been discarded by
    > 
    > This wasn't thrown out; it is still there, and fully supported.  It
    > just didn't meet everyone's requirements.  I would expect different
    > types of products to use EUI-64 than the other mechanisms.
    > 
    > >     the naming committee, then I think we must at least require
    > >     that the names be unique within the context of the NAMEPREP
    > >     character mappings, which include not only case insensitivity,
    > >     but the mapping of many specialized characters to normalized
    > >     characters.  This context also requires the prohibition of
    > >     certain characters.
    > >
    > >     This is equivalent to rewording Mark's stated rule:
    > >
    > >         - iSCSI names SHOULD be generated in a
    > >         case-insensitive manner.
    > >
    > >     to say instead:
    > >
    > >         - iSCSI names SHALL be generated using the 
    > normalized characters
    > >         that would be generated by processing through NAMEPREP.
    > 
    > I really like this; it is a much stronger statement, and NAMEPREP can
    > remove some of the ambiguity of "case-insensitive manner".
    > 
    > >     This has the advantage of allowing direct comparison,
    > >     but requires some thought during the generation of the names.
    > >
    > > It seems to me that these are the only two approaches that do not
    > > require the installation of the NAMEPREP pre-processing in the
    > > compare function.
    > 
    > The thing I really like about this is that anyone comparing iSCSI
    > names does not have to worry about any of this stuff; a byte-compare
    > is all that's needed.  Anyone generating the names only needs to
    > put in NAMEPREP if the names are based on a source that might need
    > to be mapped.  Anyone building user interfaces for this stuff has
    > the option to put in NAMEPREP to make things easier for their users,
    > but can decide this on their own.
    > 
    > > References that I found useful in this include:
    > >
    > >         draft-duerst-i18n-norm-04.txt
    > >         draft-ietf-idn-idne-02.txt
    > >         draft-ietf-idn-nameprep-05.txt
    > >         draft-skwan-utf8-dns-06.txt
    > 
    > Anyway, thanks for the reference.
    > 
    > --
    > Mark
    > 
    > > Bob Snively                        e-mail:    rsnively@brocade.com
    > > Brocade Communications Systems     phone:  408 487 8135
    > > 1745 Technology Drive
    > > San Jose, CA 95110
    > 
    > 
    > 
    > 
    > 
    > 
    > > -----Original Message-----
    > > From: Mark Bakke [mailto:mbakke@cisco.com]
    > > Sent: Tuesday, July 17, 2001 1:29 PM
    > > To: IPS
    > > Subject: iSCSI: Case-sensitivity in iSCSI names
    > >
    > > We are attempting to wrap up all of the issues surrounding
    > > the creation and comparison of iSCSI initiator and target
    > > names.  One of these is whether the names are case-sensitive.
    > >
    > > The last naming & discovery draft stated that the names are
    > > case-insensitive; this was to allow better transcribability
    > > in cases where names were communicated outside the automated
    > > discovery processes.
    > >
    > > This comes at some expense, particularly since these names
    > > are defined to allow UTF-8 encoding of international character
    > > sets.  Initiators and targets would have to include code to
    > > compare these sets.
    > >
    > > To simplify implementation and interoperability, it has been
    > > recommended that we make iSCSI names case-sensitive instead.
    > >
    > > I am fine with doing this, and I think that we could even
    > > get some of the usability back by adding these rules:
    > >
    > > - iSCSI names MUST be case-sensitive, and compared strictly
    > >   byte-for-byte.
    > >
    > > - iSCSI names SHOULD be generated in a case-insensitive
    > >   manner.
    > >
    > > I'm not sure how to properly word the latter, but the intent
    > > is that someone generating the names would not produce both:
    > >
    > >   iqn.9.com.cisco.myiscsithing
    > >
    > > and
    > >
    > >   iqn.9.com.cisco.MyIscsiThing
    > >
    > > since a user would be likely to confuse these.  Again, it doesn't
    > > affect the protocol itself, just its usability.
    > >
    > > Any thoughts?  Will it hurt anyone's plans if iSCSI names were
    > > case-sensitive?
    > >
    > > --
    > > Mark A. Bakke
    > > Cisco Systems
    > > mbakke@cisco.com
    > > 763.398.1054
    > 
    > --
    > Mark A. Bakke
    > Cisco Systems
    > mbakke@cisco.com
    > 763.398.1054
    > 
    > 
    > 
    > 
    > 
    > 
    


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