From: Colm Buckley (colm at domain tuatha.org)
Date: Fri 21 Sep 2001 - 10:46:16 IST
On Fri 21 Sep 2001 01:16, Breathnach, Proinnsias (Dublin) wrote:
> figure 48000bits per second on a good connection
> 48000 / 8 = 6000 bytes per second
Not quite. Dialup modems are asynchronous, which means that each byte
is padded out with start and stop bits, and usually parity...
typically taking each "byte" to 11 transmitted bits.
48000kb/s therefore equates to only 4.2kB/s... and there's still the
overhead of error-correction, retransmission etc.
Async modems are shite, basically. I'm still on Surf NoLimits, but I
don't think I've ever been able to get a connection faster than
26400... roll on Tiscali's satellite network.
>> In particular, while fiddling the deflate/bsdcomp options got a bit
>> of an improvement, it looks like compressed or encrypted traffic is
>> stuck at about 4 KB/sec, does that match other people's experience?
Yeah. You won't gain much in the PPP compression protocols, because
most high-speed analogue asynch modems already do run-time data
compression. Compression is all about removing redundancy; if the PPP
drivers have already stripped out redundancy in the data, then the
modem's not going to be able to improve on it much.
Colm
-- Colm Buckley : Systems Architect at domain NewWorld Commerce Business: +353 1 4334334 / colm at domain nwcgroup.com / http://www.nwcgroup.com/ Personal: +353 87 2469146 / colm at domain tuatha.org / http://www.tuatha.org/~colm/ If you think nobody cares about you, try missing a couple of payments.
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