[e2e] Question about propagation and queuing delays
David P. Reed
dpreed at reed.com
Mon Aug 22 14:08:58 PDT 2005
Christian Huitema wrote:
>
>One way to find out is to collect a large set of samples, and then look
>at the minimum value. As long as the route does not change, the
>propagation delay is the sum of the transmission times, which are
>supposed constant, and a set of positive random values. The minimum of a
>large sample is the sum of the transmission times and the minimum of the
>random values, which tends towards zero.
>
>Obviously, you have to verify the "stable route" hypothesis...
>
>
This assumes the buffering is elastic. If it includes a fixed delay
independent of load in the particular equipment (e.g. a "slotted"
multiplexed rate adapter) you could have a long buffer delay without
variation.
Not all queues are elastic. (i.e. a pair of scheduled train routes with
a transfer point can have a constant queueing delay that is the skew in
arrival vs. departures at the transfer point.).
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