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    Questions about FCIP



    I have some questions about the Fibre Channel over TCP/IP I-D.
    I understand IP networks well, but am a Fibre Channel newbie and
    am asking these questions to learn more about Fibre Channel's 
    requirements rather than to challenge the document.  Here are
    my questions:
    
    1.  Why Fibre Channel over TCP, rather than over UDP?  Is it 
        because of an expectation of lossy IP networks?  Or is it
        equally valid to put Fibre Channel over UDP (and therefore
        can be the subject of another I-D).
    2.  What are the typical values of the ED_TOV and R_A_TOV timers? 
        Do I understand this right to say that these timers effectively
        limit the latency across the IP network?
    3.  What is an acceptable loss ratio of Fibre Channel datagrams
        that still allows the SAN devices to deliver appropriate
        end user performance (order of magnitude estimate is 
        sufficient).
    
    The reasons I ask are:
    
    * I believe it is invalid to assume that IP networks are 
      necessarily more lossy than Fibre Channel networks.  A 
      well-engineered IP network, using a combination of both 
      Diff-Serv and MPLS, can achieve (close to) zero loss.
    * Stacking one reliable delivery protocol on top of another can
      possibly lead to interesting performance problems after a loss
      occurs, depending upon the timer values for TCP and Fibre Channel.
    
    Thanks in advance for your answers.
    
    Prabhu Kavi
    ----------------------------------------------------------------------
    Prabhu Kavi                     Phone:  1-978-264-4900 x125 
    Director, Adv. Prod. Planning   Fax:    1-978-264-0671
    Tenor Networks                  Email:  prabhu_kavi@tenornetworks.com
    100 Nagog Park                  WWW:    www.tenornetworks.com
    Acton, MA 01720
    


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Last updated: Tue Sep 04 01:05:57 2001
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