iSCSI: Ping Data,CmdSN

["Asai Thambi S P" <sp_asai@ctd.hcltech.com>]

hi,

I have read iSCSI draft 6.
I need clarifiaction on the issues given below:

 * NOP-Out can be sent in response to NOP-In or to test the target or to
        test the connection.

        Section 2.12:

        "The NOP-Out may be useful in the case where an initiator has been
        waiting a long time for the response to some command, and the
        initiator suspects that there is some problem with the connection."

        "A NOP-Out should also be used to confirm a changed ExpStatSN if
there is no other PDU to carry it for a long time. "

      The draft also says that the timeout value is outside the scope of the
document.

        In the former case, how do we know that we've been waiting for a
long time?
        In the latter case, how do we know that there is no other PDU's to
carry this for a long time?

* Similarly  for NOP-In,
        NOP-In can be sent
                        * in response to NOP-In
                        * to test the initiator
                        * to test the connection

        When to test the initiator or connection? How to decide it?

In case of target/initiator issuing NOP-In/NOP-Out on its own, what will be
the Ping Data?


* if CmdSN  is not equal to ExpCmdSN, what should the target do?
        suppose CmdSN > ExpCmdSN,  whether the target should assume that it
missed the commands in between and ask for retransmission of commands. 
If so, how the target asks for command retransmission.
        If not, what the target should  do?

    The initiator asks for retransmission of status or data through SNACK request. 

Is there anything similar to this for target?


 - asai.