[ILUG] Subscription ISDN ISPs
karl at jeacle.ie
Fri Jan 25 14:58:58 GMT 2002
On Fri 25 Jan 02, 13:17:19 +0000, Niall O Broin wrote:
> Modem protocols are asynchronous so even if you get a
> claimed 50Kbits/s connection your data transmission rate = 5KBytes/s
> (because every 8 bits of data are preceded by a start and stop bit hence
> 25% of the bits transmitted are pure waste from the point of view of
That's not strictly true because only the computer<->modem link is async.
The modem<->modem link uses LAP-M framing, which has a smaller overhead.
So while you are wasting bits locally on your serial link (which you can
afford to waste), you aren't wasting quite so many between the modems.
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