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    Re: iSCSI: keys/parameter dependence



    Hi Pat:
    
    Comments in text below.
    
    > The part that might cause interoperability problems is different
    > interpretations of which parameters action or acceptance is dependent on
    > others.
    
    I agree -- see below.
    
    
    > For instance, does the sentence mean that InitialR2T should be sent
    > before FirstBurstSize and that FirstBurstSize doesn't need a response when
    > the response to InitialR2T was Yes?
    
    See my responses to Mike Donahoe and Martins Krikis.  In particular,
    an offered key ALWAYs requires a response (unless this happens during
    login, in which case the responder can also just close the connection).
    The response can be Reject or NotUnderstood or Irrelevant in certain
    defined circumstances, but there must always be a response.
    
    
    > If the sentence is left in, then it should be clarified by adding something
    > such as:
    > "The definition of a key specifies whether the key is dependent on any other
    > keys."
    
    I believe the sentence should be left in and its intent remain unchanged.
    However, clarification would certainly be desirable, and would probably
    remove a lot of the current uncertainty.
    
    
    > and if any of our current keys are dependent, add to those keys
    > "This key is dependent on <key names>."
    > If none are currently dependent, it would be reasonable to add to 11
    > "Currently,
    > no Login/Text Operational keys are dependent."
    
    There are dependencies, so such a statement cannot be added to section 11.
    
    The existence of a dependency between FirstBurstSize and
    MaxBurstSize is already clear from the statement in section 11.15:
    "FirstBurstSize MUST NOT exceed MaxBurstSize."  My earlier e-mail to Mike
    Donahoe details this dependency.
    
    The existence of a dependency between OFMarker and OFMarkInt, and between
    IFMarker and IFMarkInt, is implied by the statements in section A.3.2:
    "When the interval is unacceptable the responder answers with
    "Reject".  Reject is resetting the marker function in the spcified
    direction (Output or Input) to No."
    This last sentence should probably be reworded to say:
    "A response value of "Reject" to an OFMarkInt (IFMarkInt) key resets the
    corresponding OFMarker (IFMarker) key value to "No"."
    
    
    Besides these two dependencies just mentioned,
    I am aware of two other dependencies, and it would certainly would not
    hurt to have all these made explicit in the appropriate sections of the
    standard.  If anyone else has other dependencies to add, we should
    all know about these now! :)
    
    1. The table in section 11.12 describes the action taken on the four
    combinations of InitialR2T = Yes/No and ImmediateData = Yes/No.
    The combination InitialR2T=Yes and ImmediateData=No means "Unsolicited
    data disallowed".  Therefore, FirstBurstSize becomes "Irrelevant" for
    this combination.  This means that if FirstBurstSize is offered after
    an offer of ImmediateData=No which is accepted, and either an explicit
    offer of InitialR2T=Yes which is accepted or no explicit offer of
    InitialR2T (in which case the applicable default value is Yes),
    then a reply of FirstBurstSize=Irrelevant MAY be returned
    (alternatively, a valid value can also be given in the reply).
    
    2. Since the default value of OFMarker (IFMarker) is No, an offer
    of OFMarkInt (IFMarkInt) without a previous explicit offer of
    OFMarker=Yes (IFMarker=Yes) MAY generate the reply
    OFMarkInt=Irrelevant (IFMarkInt=Irrelevant) -- it can, of course,
    also reply with a valid value or with "Reject", as specified in
    section A.3.2.
    A similar reply of OFMarkInt=Irrelevant (IFMarkInt=Irrelevant) MAY
    also be generated if the previous explicit offer of OFMarker=Yes
    (IFMarker=YES) was refused by a reply of OFMarker=No (IFMarker=NO).
    
    Best,
    
    Bob Russell
    InterOperability Lab
    University of New Hampshire
    rdr@iol.unh.edu
    603-862-3774
    


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Last updated: Mon Jun 03 18:18:41 2002
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