I see, thanks a lot, and for your question about where the speed is being
show, it's both in the download window (firefox download window) and also a
network speed monitor over the whole system, of course they don't show the
same numbers but they both show the small increase in the start, and I don't
really know what 'granularity' means.

~Coalwater~


On Mon, Mar 1, 2010 at 1:33 AM, KwikOne <[email protected]> wrote:

> You did not indicate "where" your download speed is being shown/
> calculated, nor the time
> granularity used. Quite often the speed spike are not really spikes
> (especially when first
> starting the download) because of the way the download speed is being
> calculated and
> as time goes on the download speed stays constant, or it will drop off
> then stay constant.
> Think of it this way (note the figures are just approximates as
> illustration only with rounding)...
> 1) download requested from server
> 2) first bit of data arrives; calculated speed is roughly amount of
> data / 1 ms. (smallest granularity)
>    = very high speed (1000 times amount of data)
>    (example - first chunk is 1400 Byte, this would give approx
> 1,400,000 Byte/sec rate)
> 3) next bit of data arrives; calculated speed is roughly total amount
> of data / (time from first bit
>    to second bit) = lower speed (unless the server is close enough
> that you have < 1ms time)
>    (example - second chunk 1400 Byte arrives 100 ms later which would
> give approx
>     2800 Byte for 100 ms. = 28,000 Byte/sec).
> 4) next bit of data arrives (example 1400 Byte 100 ms later which
> calculates out to
>    4200 Byte in 200 ms. = 21,000 Byte/sec).
> and so on... get the picture (it all depends upon how the calculations
> are done)?
> Notice how the rate is dropping off when in actual fact in this
> example it is actually 14,000 Byte/sec.
>
>
> On Feb 22, 7:37 pm, Coalwater <[email protected]> wrote:
> > Well i noticed that i when ever i start a download, the download speed
> > starts with a very high speed spike in the beginning that could reach
> > up to 3x of my bandwidth, and last for like 3 to 10 secs then starts
> > to gradually drop till it reaches my usual expected download speed,
> > this isn't really a problem but i would really like to understand it
> > from the networks point of view, how does it get past the ISP limit
> > even if for a very short period of time, because i might think of
> > using it to my advantage somehow if i understand it, Hope some
> > networks guy around here could explain to me :D
> > oh and it doesn't depend on the connection type nor the operating
> > system, i saw this happen on cable connection and mobile broadband,
> > windows and ubuntu so it doesn't have any thing to do with those
> > differences.. oh and it works also with both normal single connection
> > download and download accelerators that use multipart downloading
>
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