Another shot at codes and please comment

[sandeepj@research.bell-labs.com (Sandeep Joshi)]

Julian,

I'd prefer this over the alternating opcode assignments.
(where nop-out was 0 and nop-in was 1)

Could you also define the behaviour if a vendor-specific 
opcode was not recognized ?   

I presume we always want to drop the session, since these 
opcodes would only be used if the target and initiator 
recognized/negotiated (in a vendor-specific way) their
use during session initiation.

-Sandeep

> Here is a another version of the opcodes part:
> 
> 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)
>       0x01 SCSI Command (encapsulates a SCSI Command Descriptor Block)
>       0x02 SCSI Task Management Command
>       0x03 Login Command
>       0x04 Text Command
>       0x05 SCSI Data-out (for WRITE operations)
>       0x06 Logout Command
>       0x10 SNACK Request
> 
>    Valid target opcodes are:
> 
> 
>       0x20 NOP-In (from target to initiator)
>       0x21 SCSI Response (contains SCSI status and possibly sense
>       information or other response information)
>       0x22 SCSI Task Management Response
>       0x23 Login Response
>       0x24 Text Response
>       0x25 SCSI Data-in (for READ operations)
>       0x26 Logout Response
>       0x31 Ready To Transfer (R2T - sent by target to initiator when it is
>       ready to receive data from initiator)
>       0x32 Asynchronous Message (sent by target to initiator to indicate
>       certain special conditions)
>       0x3f Reject
> 
>    Initiator opcodes 0x1c-0x1e and target opcodes 0x3c-0x3e are vendor
>    specific codes.
> 
> 
>    Please comment,
>    Julo
>