Re: Multiple Connections. How would they work?

[julian_satran@il.ibm.com]

The 00 draft (Adelaide) had the commands go down over one specific control
 stream while the data went on any available connection.
Synchronizing them and providing for hardware implementation across several
adapters was felt to be complex.

However command ordering was trivial.

The symmetric model in 01 requires ordering and this is why you have the
command ordering.
A proposal to get back to the asymmetric model but decide ahead of time (?
when) what
path data will be taking was forwarded by Kalman.

We call this the asymmetric model (it can still evolve).

I hope this helps.

Regards,
Julo

Robert Snively <rsnively@Brocade.COM> on 06/09/2000 18:46:40

Please respond to Robert Snively <rsnively@Brocade.COM>

To:   ips@ece.cmu.edu
cc:    (bcc: Julian Satran/Haifa/IBM)
Subject:  Multiple Connections.  How would they work?




What am I missing?  The reason I felt that iSCSI might possibly
work was the text from 2.2.4 of draft-satran-iscsi-01.txt.

     " For SCSI commands that require data and/or parameter
     transfer, the (optional) data and the status for a
     command must be sent over the same TCP connection that
     was used to deliver the SCSI command (connection
          allegiance).  Thus if an initiator issues a READ
     command, the target must send the requested data followed
     by the status to the initiator over the same TCP connection
     that was used to deliver the SCSI command."

>From this, I extrapolated that multiple connections and sessions
were mechanisms to manage multiple paths, each of which would
carry all the traffic related to a single command, probably with
no ordering among them.  I had expected TCP/IP and iSCSI state
required for execution of an iSCSI operation to be contained within
a single NIC.

How does this map into the multiple connection structures that are
being discussed?

How do the multiple connection structures map into the low cost highly
efficient hardware assisted NIC implementations that presently typify
SCSI implementations?