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    RE: iscsi : Fragmentation & Reassembly issues in iSCSI.



    It is better to leave a seperate, possibly lower limit for
    PingMaxReplyLength
    
    -----Original Message-----
    From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
    Santosh Rao
    Sent: Friday, January 19, 2001 2:00 PM
    To: julian_satran@il.ibm.com; ips@ece.cmu.edu
    Subject: Re: iscsi : Fragmentation & Reassembly issues in iSCSI.
    
    
    julian_satran@il.ibm.com wrote:
    
    > <js> I will introduce in 04 a statement saying that that
    PingMaxRelayLength
    > will be limited by the lowest of the two </js>
    
    Julian,
    
    The fragmentation issue as explained in the above example is also applicable
    for the Login and Text Commands. (TotalText > DataPDULength).
    
    In the case of these commands, a "F" bit is required in bit 7 of byte 1 of
    the
    command & response PDUs to indicate the last command or response PDU due to
    the fragmentation issues that arise from TotalText & DataPDULength.
    
    
    > Solution :
    > =======
    > Specify explicitly in Appendix C that DataPDULength is only applicable
    > for SCSI Command PDU and SCSI Data PDU. The current definition is open
    > to being mis-interpreted as a form of iSCSI MTU, something that can
    > result in the iSCSI layer having to deal with fragmentation and
    > re-assembly issues for non-SCSI PDUs.
    >
    > <js> What would be those? Text commands? Login? Nops? Having a single
    limit
    > seemms simpler </js>
    
    On the lines of your above solution, (based on a single limit), removal of
    PingMaxReplyLength should be considered and implicitly use DataPDULength as
    the PingMaxReplyLength. This ensures only 1 limit for NOP-OUT/NOP-IN.
    
    Regards,
    Santosh
    
    
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Last updated: Tue Sep 04 01:05:47 2001
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