How to calculate theoretical max download speed from upload speed (ADSL) ?

Discussion in 'NZ Computing' started by GraB, Oct 28, 2006.

  1. GraB

    GraB Guest

    I don't seem to be able to find a calculator or formula online.

    Disregarding line condition and contention ratios, etc, how does one
    calculate the theoretical maximum download speed as limited by your
    upload speed?
    GraB, Oct 28, 2006
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  2. It's not really calculable as it depends on the protocol, the configuration of
    the machines at each end, how many hops in the path, how each hop is
    configured, how the rate limiting is applied etc etc.
    Mark Robinson, Oct 28, 2006
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  3. GraB

    Zonky Guest

    This is what you are looking for
    Zonky, Oct 28, 2006
  4. GraB

    GraB Guest

    I was really trying to find how much the upload connection speed
    limits the download speed, all other things being optimum. EG If I
    was on a 32kbps upload it won't be able to send answering packets fast
    enough to sustain a 7.6M connection. But how fast a download can it
    sustain, or 128kbps upload sustain or a 512kbps upload speed?

    I have my MTU set to 576. Just ran a check with TCPOptimizer which
    confirms that the optimum setting is 576 as packets larger than that
    are fragmented.
    GraB, Oct 29, 2006
  5. GraB

    Mark C Guest

    That's a really stuffed MTU.
    (In other words: What is fragmenting packets larger than that?)

    Of course it could be *YOUR* TCP stack that is fragmenting the
    packets. If you had MTU set to 576 and then you checked fragmenting,
    it *would* report anything larger than 576 as fragmented.
    Try setting MTU to 1500 (and possibly re-booting) and try the test
    Mark C, Oct 29, 2006
  6. GraB

    Mark C Guest

    This may be applicable:
    Mark C, Oct 29, 2006
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