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    Re: Symmetric vs Asymmetric



    > The biggest issue with the "asymmetric" model is that it is NOT "asymmetric"
    > when there is only 1 TCP connection.  When there is only one TCP connection, 
    it
    > is the "symmetric" model - both commands and data on the same TCP connection.
    > Then, when there is more than one TCP connection, the behavior is different.
    > It's always easier to implement something that operates that same way all the
    > time, than two different behaviors.
    > 
    > I propose that the asymmetric model mandate at least two TCP connections
    > (implies that at least one physical connection will have at least two TCP
    > connections running on it) - one for commands, the other for data.  This has
    > other advantages, like commands not being flow controlled by large transfers 
    of
    > data.
    
    That's not a bug, that's a feature! Having the asymmetric degenerate
    into symmetric with just one connection is a good thing.  For starters
    it is easier to implement initially or in cheap devices and doesn't
    have the baggage that a true symmetric design would require
    but is not needed with one connection. I would oppose mandating
    two connections minimum, if flow control is a problem then the defacto
    configuration will be two connections, but lets not require it.
    
    Personally I would still prefer one connection per LUN, but the
    proposed asymmetric model is a good compromise. You could
    still deploy an implementation with a connection per LUN and not
    have any significant unnecessary baggage. Not true of the symmetric
    model.
    
    	-David
    	
    
    


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Last updated: Tue Sep 04 01:07:29 2001
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