Re: iSCSI: multiple sessions b/n a pair of WWUIs.

["John Hufferd" <hufferd@us.ibm.com>]

Santosh,
I think I am beginning to see the problem.  A given iSCSI Initiator Port
can NOT have a second session with the same iSCSI Initiator Port and be
consistent with SCSIness.  The second session could be started with another
ISID, (to the same iSCSI Target Port) but if the session was established it
would not have any of its commands and data handled via any techniques
defined by SCSI or iSCSI.  In fact its use would require a wedge driver.
This is the exact confusion I was trying to avoid.  Technically if you were
actually able to start another Session to the same Target Port, it would
be, by definition another iSCSI Initiator Port.   The two different Ports
would need to be coordinated by what we have been calling a Wedge Driver.

Today, the way we use multiple Fibre Channel Initiator Ports connected to
the same Fibre Channel Target Ports is by use of Wedge Drivers.  I think
what you are suggesting causes the need for a Wedge Drivers to integrate
the iSCSI Initiator Ports.  Not sure that we want to cause this type of
thinking, by accident.  One of the reasons for Multiple Connections per
Session was to remove the "Hard" need for Wedge Drivers.

OK, that's what I think our misunderstanding is all about.  If I am
mistaken, please set me straight.
.
.
.
John L. Hufferd
Senior Technical Staff Member (STSM)
IBM/SSG San Jose Ca
(408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
Internet address: hufferd@us.ibm.com


Santosh Rao <santoshr@cup.hp.com>@cup.hp.com on 05/08/2001 05:44:41 PM

Sent by:  santoshr@cup.hp.com


To:   John Hufferd/San Jose/IBM@IBMUS
cc:   Black_David@emc.com, ips@ece.cmu.edu
Subject:  Re: iSCSI: multiple sessions b/n a pair of WWUIs.



John,

By the name-disc definition, an iSCSI initiator or target port is a
logical entity that constitutes the end points of a session.

Hence, there never can be 2 sessions b/n the *same* 2  initiator &
target port. Each session established spawns a *new* initiator and
target iSCSI port.

Going by the above semantics, there is always only 1 ISID/TSID per iSCSI
Initiator/Target port.

Hence, I'm unable to understand your statements below.

As for the uniqueness of ISID across all initiators, is there any reason
not to allow implementations to do that ? I would have thought that is
the most typical use of an ISID and also allows initiators to lookup
their target structures based on ISID.

Regards,
Santosh

John Hufferd wrote:
>
> Also, since a second session by the same iSCSI Initiator Port, to the
same
> iSCSI Target Port is not, in my opinion "legal", it is not clear to me
that
> any given iSCSI Port needs any more then one ISID.  I
>
> Therefore, I suggest that we Not put any such notes, like you suggest, in
> the draft, but in fact encourage a single ISID/TSID per iSCSI
> Initiator/Target Port.




> To:   Jim Hafner/Almaden/IBM@IBMUS, marjorie_krueger@hp.com
> cc:   ips@ece.cmu.edu
> Subject:  RE: iSCSI: multiple sessions b/n a pair of WWUIs.
>
> While Jim's correct ... in Marj's defense, what
> she wrote is a fairly obvious way to implement
> it, and that might be worth noting in the draft.
>
> --David