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    RE: iSCSI : New PDU opcode usage in rev 5.92



    Santosh,
    
    Is it not the case that requests go in the direction from the Initiator to
    Target,
    where Target is the one "listening" for new connections on the well-known
    port?
    A dual mode scsi implementation therefore has two separate sessions and sets
    of connections.
    One set is [I->DualModeTarget] and the other is [DualModeInitiator->T]
    and the connections are independent. If I and T happens to be the same
    system, you
    can not use a single connection for bidirectional sessions between the two.
    
    So if you receive a PDU from a target, you can only do so with SourcePort
    set to
    well-known-port, and it must be a Response from target. May be I'm assuming
    something
    that is not valid...
    
    Venkat Rangan
    Rhapsody Networks Inc.
    http://www.rhapsodynetworks.com
    
    -----Original Message-----
    From: Santosh Rao [mailto:santoshr@cup.hp.com]
    Sent: Wednesday, April 18, 2001 6:47 PM
    To: ips@ece.cmu.edu
    Subject: iSCSI : New PDU opcode usage in rev 5.92
    
    
    Julian & All,
    
    I've got a quick question on how the new opcode layouts would work for
    dual mode scsi implementations. (i.e. initiators that responded in
    target mode or targets that acted as initiators also).
    
    The new opcode layout is :
    
    ----------------
    X|I| | | | | | |
    ----------------
    7 6 5 4 3 2 1 0
    
    where bits 5-0 -> opcode
    X -> retry bit
    I -> immediate bit
    
    The same values are used for the command as well as response opcodes and
    bits X & I are intended to both be set to 1 by targets.
    
    i.e. opcode for scsi command = scsi response = 0x01. the distinction b/n
    command and response is based on targets setting X & I bits to 1.
    
    Now, if an initiator [capable of target mode] sent the following
    commands, how would they be interpreted :
    
    1) 0xc4.
    is this a text command being retried in immediate mode, 
    or is it a text response ?
    
    2) 0xc1
    is this a scsi command being retried in immediate mode,
    or is it a scsi response ?
    
    3) 0xc2
    is this a scsi task mgmt command being retried in immediate mode,
    or is it a scsi task mgmt response ?
    
    etc.....
    
    - Santosh
    
    -- 
    #################################
    Santosh Rao
    Software Design Engineer,
    HP, Cupertino.
    email : santoshr@cup.hp.com
    Phone : 408-447-3751
    #################################
    


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Last updated: Tue Sep 04 01:04:59 2001
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