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    RE: iSCSI - opcodes



    Julian,
    
    I am not sure what decision was taken on this, but I would also vote for
    having the direction bit as the MSB (bit-5) in the opcode.
    
    -Ayman
    
    
    > -----Original Message-----
    > From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
    > julian_satran@il.ibm.com
    > Sent: Monday, May 28, 2001 6:54 AM
    > To: ips@ece.cmu.edu
    > Subject: RE: iSCSI - opcodes
    >
    >
    >
    >
    > The new codes are in the 07 draft.   Although I've put back the bit that
    > shows direction I seriously doubt that
    > it's original purpose (to make life easier for analyzers) is as
    > relevant as
    > it was.
    >
    > Julo
    >
    > "Martin, Nick" <Nick.Martin@compaq.com> on 01-05-2001 01:48:00
    >
    > Please respond to "Martin, Nick" <Nick.Martin@compaq.com>
    >
    > To:   Julian Satran/Haifa/IBM@IBMIL
    > cc:
    > Subject:  RE: iSCSI - opcodes
    >
    >
    >
    >
    > Julian,
    >
    > I was not among the incensed.  I would say puzzled.  Although the bit may
    > not be not critical to initiators or targets who presumably know what they
    > are, it is handy at least for network analyzer displays.
    >
    > Since it now still consumes a bit, I would have made it the MSB of the
    > Opcode field as in previous drafts (currently bit 5 or 0x20).  However I
    > can
    > cope with your selection ((Opcode & 0x3e)>>1) :).
    >
    > The 2F reject instead of 3F (or 1f) for reject was another puzzler.
    > Presumably you wanted a fence between unused reserved opcodes and vendor
    > specific codes.
    >
    > Thanks,
    > Nick Martin
    >
    > -----Original Message-----
    > From: julian_satran@il.ibm.com [mailto:julian_satran@il.ibm.com]
    > Sent: Friday, April 27, 2001 12:38 AM
    > To: ips@ece.cmu.edu
    > Cc: matt_wakeley@agilent.com
    > Subject: iSCSI - opcodes
    >
    >
    >
    >
    > Fellow iSCSI fans,
    >
    > Some were incesed by the lak of a "direction bit" in the opcodes in draft
    > 06.
    > Here is an attempt to a new list (having a bit for direction back - as the
    > LSB ).
    > To gain some reserved space I've curtailed the vendo-specific
    > codes to 4 in
    > each direction.
    >
    >
    > Please comment,
    > Julo
    >
    > 1.1.1.1   Opcode
    >
    >    The Opcode indicates what type of iSCSI PDU the header encapsulates.
    >
    >    The Opcodes are divided into two categories: initiator opcodes and
    >    target opcodes. Initiator opcodes are in PDUs sent by the initiators
    >    (request PDUs), and target opcodes are in PDUs sent by the target
    >    (response PDUs).
    >
    >    Initiators MUST NOT use target opcodes and targets MUST NOT use
    >    initiator opcodes.
    >
    >    Valid initiator opcodes defined in this specification are:
    >
    >
    >       0x00 NOP-Out (from initiator to target)
    >       0x02 SCSI Command (encapsulates a SCSI Command Descriptor Block)
    >       0x04 SCSI Task Management Command
    >       0x06 Login Command
    >       0x08 Text Command
    >       0x0a SCSI Data-out (for WRITE operations)
    >       0x0c Logout Command
    >       0x10 SNACK Request
    >
    >    Valid target opcodes are:
    >
    >
    >       0x01 NOP-In (from target to initiator)
    >       0x03 SCSI Response (contains SCSI status and possibly sense
    >       information or other response information)
    >       0x05 SCSI Task Management Response
    >       0x07 Login Response
    >       0x09 Text Response
    >       0x0b SCSI Data-in (for READ operations)
    >       0x0d Logout Response
    >       0x11 Ready To Transfer (R2T - sent by target to initiator when it is
    >       ready to receive data from initiator)
    >       0x13 Asynchronous Message (sent by target to initiator to indicate
    >       certain special conditions)
    >       0x2f Reject
    >
    >    Initiator opcodes 0x38, 0x3a, 0x3c and 0x3e and target opcodes 0x39,
    >    0x3b, 0x3d and 0x3f are vendor specific codes.
    >
    >
    >
    >
    >
    
    


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Last updated: Tue Sep 04 01:04:33 2001
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