RE: a vote for asymmetric connections in a session

[Joshua Tseng <jtseng@NishanSystems.com>]

>As Julian has stated in a different thread, the purpose of the "sliding
>windows" in iSCSI is not for congestion management.  It is simply there to
>handle the case where if a connection goes down in a multiple connection
>session, it prevents the remaining connections from overwhelming the target
>with new commands that it can't process due to missing commands that where
on
>the broken connection.

Matt,

In the event of a failed connection, the sliding window isn't going to help
much since you have to first detect the failed connection.  Once this is
accomplished, the initiator will know which command was lost for sure, but
will not know how many, if any, of the subsequent commands sent after the
lost command, were also lost.  I presume, the initiator will then
retransmit all commands without knowing whether or not they were lost,
rather
than wait for the target to advance the acknowledgement counter.

This is all awesome and impressive behavior, exactly what we want.  The only
problem is this exact same behavior can be had without the windowing
mechanism.

>Since all of this runs on top of TCP, and TCP performs congestion
>management,
>why must iSCSI perform congestion management on top of TCP?

Please see my reply to John Hufferd.

Josh