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    RE: iscsi : numerical negotiation wording is ambiguous



    Hi Julian,
    
    I and my collegues have always assumed that the answer to an offered
    parameter was the result of the negoitated value.  This seems the most
    appropriate behaviour as it confirms the value that both parties will use
    (it certainly helps in debugging).
    
    Cheers
    
    Matthew
    
    
    -----Original Message-----
    From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
    Sent: Thursday, September 27, 2001 9:55 AM
    To: ips@ece.cmu.edu
    Subject: Re: iscsi : numerical negotiation wording is ambiguous
    
    
    
    Santosh,
    
    I understood what you wording means but I am not sure that we want all the
    side-effects.
    The negotiation as defined  now allows both parties requester or responder
    to state their wishes and the LAW
    insatiate the result in both.
    
    Your wording means that the responder selects the value according to the
    rule. What if the responder is either a rogue or
    just a simple minded target.  Let me give an example:
    
    I am building a simple minded target that has an 8K buffer and says  always
    (has it wired) DataPDULength=8192
    in its first Login response (that is his buffer).
    
    If an initiator sends him as a "offer" or as a "responder" 16192 then with
    the current wording things are fine and both will
    have settled to 8192.
    
    If the initiator sends an offer of 4096 and the target gives his (only
    thing he knows) 8192 it is still fine - both select 4096.
    
    With your wording some of the negotiations will fail since you assume that
    the rule should be expressed in building the answer and not in selecting
    the result.
    
    In the end in both case you have to do selections at both target and
    initiator but the current rule enables simple-minded prewired messages
    while your does not (the responder message defines the selection and the
    offerer has to check it).
    
    Sorry for this long message for such a simple question.
    
    Julo
    
    
    
    
     
    
                        Santosh Rao
    
                        <santoshr@cup.       To:     ips@ece.cmu.edu
    
                        hp.com>              cc:
    
                        Sent by:             Subject:     Re: iscsi : numerical
    negotiation wording  
                        owner-ips@ece.        is ambiguous
    
                        cmu.edu
    
     
    
     
    
                        26-09-01 23:16
    
                        Please respond
    
                        to Santosh Rao
    
     
    
     
    
    
    
    
    
    Julian,
    
    What is the responding party supposed to offer ? Is it supposed to
    determine the result of the
    negotiation (higher or lower value, as the case may be) and send that as
    its response ?
    
    Or, is it supposed to send in its numerical value and the initiator picks
    the higher or lower of
    the 2 ?
    
    This does'nt come across clear enough in the definition and is open to
    mis-interpretation. Please
    see the suggested re-word in its place.
    
    Thanks,
    Santosh
    
    
    Julian Satran wrote:
    
    > Santosh,
    >
    > I am missing something. The rule states what value both parties should
    have
    > after both have seen the two values.
    > Obviously we assume that no error occurs and the responder value is seen
    y
    > the offering party or the negotiation fails.
    >
    > What exactly is ambiguous about it?
    >
    > Julo
    >
    >
    >                     Santosh Rao
    >                     <santoshr@cup.       To:     ips@ece.cmu.edu (ips)
    >                     hp.com>              cc:
    >                     Sent by:             Subject:     iscsi : numerical
    negotiation wording is
    >                     owner-ips@ece.        ambiguous
    >                     cmu.edu
    >
    >
    >                     26-09-01 19:59
    >                     Please respond
    >                     to Santosh Rao
    >
    >
    >
    > Julian & All,
    >
    > The definition of numerical negotiation in Section 2.2.4 of Rev 7.97
    > reads :
    >
    > "In numerical negotiations, the offering and responding party state
    >  a numerical value. The result of the negotiation is key dependent;
    >  frequently the lower or the higher of the two values is used."
    >
    > The above definition is ambiguous, since it does not specify whether it
    is
    > the originator or the responder that computes the result of the
    > negotiation.
    >
    > i.e. Is it the responsibility of the target to pick the higher or lower
    of
    > the 2 values and respond with the result of the negotiation ?
    >
    > OR :
    > Is it the originator that has to pick the result of the negotiation
    > based on the key it sent and the key it got back ?
    >
    > I would suggest that the wording be clarified to indicate that the
    > responder picks the result of the negotiation and sends this result back
    > in its response for this key.
    >
    > Perhaps, some re-wording along the following lines may be in order :
    >
    > "In numerical negotiations, the offering party states a numerical
    >  value, and the responding party states the result (operational value)
    >  after the negotiation.  The result of the negotiation is key
    >  dependent; responder determines it based on the lower or the higher
    >  of the two values - offering party's value, and what the responder
    >  can support."
    >
    > Comments ?
    >
    > Regards,
    > Santosh
    >
    > --
    > #################################
    > Santosh Rao
    > Software Design Engineer,
    > HP, Cupertino.
    > email : santoshr@cup.hp.com
    > Phone : 408-447-3751
    > #################################
    
    
    
    #### santoshr.vcf has been removed from this note on September 27 2001 by
    Julian Satran
    
    
    


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Last updated: Fri Sep 28 17:17:17 2001
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