Calculating propagation delay & transmission delay

Discussion in 'Cisco' started by Stone, Sep 27, 2006.

  1. Stone

    Stone Guest

    Hi Experts,
    Does anyone know how to calculate propagation delay & transmission
    What's the relation between them and bandwidth?

    Service Nova Scotia, Canada
    Stone, Sep 27, 2006
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  2. Stone

    stephen Guest

    sounds like homework - but a working engineer rule of thumb (which you
    probably wouldnt get marks for):

    propagation delay is "how long to get a signal from A to B" - often applied
    to high speed links (in my case almost always fibre). limited by speed of
    light or other signal in the medium.

    often this isnt as easy as measuring on a map - you dont know the route, and
    a modern DWDM system may have a fair bit of extra compensation fibre
    compared to geographic route distance.

    Also need the right "speed" - speed of light in fibre is approx 2/3 of

    transmission delay is "how long to get there" - propagation delay + delays
    in equipment + other relevant delay, such a Q'ing and serialisation.

    both terms really are context dependent.
    there isnt one - in a network they are independent variables.

    if you are discussing a "connection" using something like TCP, then the
    protocol has constraints driven by available bandwidth and end to end round
    trip delay.
    stephen, Sep 27, 2006
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