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    RE: iscsi: Data PDU in two Sequence multiplexing issue



    
    That depends on why the initiator is sending the data. If we are
    talking solely about unsolicited data then you are correct, all
    the unsolicited data for command N must be sent before any
    unsolicited data for command N+1. In your example we must see A1,
    A2, B1, B2.
    
    However, your second sequence can be valid if there are solicited
    data involved. There are at least two valid scenarios for A1, B1,
    A2, B2:
    
    First A1 and B1 are unsolicited data and are FirstBurstSize big.
    The initiator would then have to see R2T-A2 and R2T-B2 in that
    order. Where R2T-A2 means the R2T requesting PDU A2.
    
    Alternatively all the data could be solicited and A1 and B1
    satisfy R2T-A1 and R2T-B1 respectively.
    
    What 3.2.4.1 is telling you is that the target can not assume the
    PDU following a command PDU is the corresponding unsolicited
    data. In fact pretty much any PDU can come next, the only thing
    that is guaranteed is that the next unsolicited DATA-OUT PDU will
    be for command in question.
    
    - Rod
    
    -----Original Message-----
    From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On
    Behalf Of
    Sanjay Goyal
    Sent: Friday, June 06, 2003 12:58 PM
    To: ips@ece.cmu.edu
    Subject: iscsi: Data PDU in two Sequence multiplexing issue
    
    
    Hi,
    Can somebody please comment,
    
    This is what I am not very clear about, from the specification.
    -----------------
    10.8 says: Within a connection, outstanding R2Ts MUST be
    fulfilled by the initiator in the order in which they were
    received.
    
    3.2.4.1 says: When unsolicited data is used, the order of the
    unsolicited
    data on each connection MUST match the order in which the
    commands
    on that connection are sent. Command and unsolicited data PDUs
    may
    be interleaved on a single connection as long as the ordering
    requirements of each are maintained (e.g., command N+1 MAY be
    sent
    before the unsolicited Data-Out PDUs for command N, but the
    unsolicited Data-Out PDUs for command N MUST precede the
    unsolicited
    Data-Out PDUs of command N+1).
    ------------------
    
    
    if we have two Data-out sequences A and B of 2 pdus each, to be
    sent on the
    same connection.
    this is how I think they will be sent
    PDU 1 of A -> PDU2 of A  -> PDU1 of B -> PDU2 of B
      What I am trying to verify is that the below sequence is valid
    or not.
    PDU 1 of A  -> PDU 1 of B -> PDU2 of A -> PDU2 of B
    
    Regards
    Sanjay Goyal
    
    
    
    


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Last updated: Fri Jun 06 22:19:17 2003
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