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    RE: iSCSI: Framing Steps

    How wonderfull to have among us people that can tell us in one short sentence why ATM failed [to reach the desktop because otherwise it is still gaining ground].  That adds a lot of clarity and technical argument to our discussion.  Julo

    Paul Koning <>
    Sent by:

    29-01-02 22:05

            Subject:        RE: iSCSI: Framing Steps


    Excerpt of message (sent 29 January 2002) by Somesh Gupta:
    > While I support a generic direct data placement model,
    > the following are additional points for consideration for
    > analysis of memory bandwidths and sizes.
    > 1. A 10G link dropping packets will not do TCP at 10Gbps.
    > The rate drops as the packet loss increases. I don't recall
    > but Franco or Victor from Nortel had posted an equation once.

    A very old (40 years?) rule of thumb is that 1% loss costs you 50% in
    throughput.  I expect that it gets a lot worse as links get faster.
    > ...
    > 3. The analysis of 10Gbps, half way round the world
    > was initially used in this debate. ALthough interesting, the person
    > with the scenario above is not going to blink at the cost of
    > 256MBytes of fastest memory considering what they are paying
    > for the link.


    One reason ATM failed as a LAN is that its design was burdened with
    complexity based on that sort of scenario.  (In other words: "it has
    to work at umpteen Gig, across the globe, and only use a tiny little
    bit of memory because implementations can't handle a megabyte of

    A design optimized for the combination of very high bit rate and very
    long latency will inevitably be way overpriced for the predominant
    case, which is the LAN case.



Last updated: Tue Jan 29 17:17:59 2002
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