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    Re: iSCSI: MaxRecvPDULength simplification




    The simplification you are talking about is illusory. Currently this requires SNACK to require all data(RL = 0).
    The restriction you propose instead is far more severe (and unwarranted).

    Julo


    Michael Schoberg <michael_schoberg@cnt.com>
    Sent by: owner-ips@ece.cmu.edu

    27-03-02 01:19
    Please respond to Michael Schoberg

           
            To:        "IPS Reflector (E-mail)" <ips@ece.cmu.edu>
            cc:        
            Subject:        iSCSI: MaxRecvPDULength simplification

           


    I've looked over some of the reflector messages regarding MaxRecvPDULength negotiation (back to Oct 2001).  I can't find the discussion of why this value must be available for negotiation outside of login.  It really complicates SNACK and Task Reassignment if the initiator can change this value on-the-fly.  Would it be too restrictive to propose the following rules?
     
    1) MaxRecvPDULength is negotiated only at login before FFP.
     
    2) For message-level recovery, a connection must be prepared to accept the MaxRecvPDULength of the connection it's providing fail over capability for.  It doesn't seem unreasonable to expect fault tolerant configurations to comply with this.  It would simply be stating that RecoveryLevel 2 devices should be somewhat matched in this capability.
     
     
     
     -----Original Message-----
    From:
    Julian Satran [mailto:Julian_Satran@il.ibm.com]
    Sent:
    Tuesday, March 26, 2002 1:50 AM
    To:
    Michael Schoberg
    Cc:
    IPS Reflector (E-mail); owner-ips@ece.cmu.edu
    Subject:
    Re: iSCSI: SNACK RunLength


    Michael,


    The paragraph says that if you issue a SNACK after the MaxPDURecvLength has decreased you should use RunLength 0 (meaning all) instead of a specific runlength which might not be accurate anymore.


    Julo


    Michael Schoberg <michael_schoberg@cnt.com>
    Sent by: owner-ips@ece.cmu.edu

    25-03-02 19:43
    Please respond to Michael Schoberg

           
           To:        "IPS Reflector (E-mail)" <ips@ece.cmu.edu>

           cc:        

           Subject:        iSCSI: SNACK RunLength


         



    Am I just not reading this or can this paragraph use some help?  Can someone
    give an interpretation?

     9.16.3  RunLength
                                    ...

             The first data SNACK, issued after initiator's MaxRecvPDULength
             decreased, for a command issued on the same connection before the

             change in MaxRecvPDULength, MUST use RunLength "0" to request
             retransmission of any number of PDUs (including one).  The number
    of
             retransmitted PDUs in this case, may or may not be the same as
    the
             original transmission, depending on whether loss was before or
    after
             the MaxRecvPDULength was changed at the target.


    Does this refer to something like:

    For connections with unacknowledged PDUs that undergo MaxRecvPDULength
    negotiation ...






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