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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iSCSI - opcodesThe 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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