On Thu, 2 Mar 2000, Nick Hilliard wrote:
> Dave Burke wrote:
> > The mean connection for a v.90 modem is about 44 kilo bits per second,
> > which when translated to bytes is 5.5 kilo bytes per second.
> > Now thats your full bandwidth, you must cater for the TCP/IP over head
>> TCP/IP overhead accounts for about 10% of the traffic passing over a given
> link, + or - a little, although this can vary due to things like packet
> header or datalink compression and so forth.
The best you'll get from a V.90 modem is in the 40kbit/sec. region. You
might get 44, but I wouldn't imagine that's the mean. To convert modem
bits/sec. to bytes/sec. you must divide by 10, not 8, as a modem is an
asynchronous device and timing is by start and stop bits, which are pure
waste.
> Ah, another misconception in the making: the fallacy that the number of
> people logged in affects the quality of the modem connection. Not true,
> folks: it doesn't matter whether you have 1 or 100 people logging in.
Of course it does - it makes no difference to each individual modem
connection, but your providers bandwidth to wherever is shared among all
the users - in this case the more the merrier is definitely untrue.
> 4.4kbytes/sec on a v.90 modem is fairly respectable, and probably well
> reflects the quality of your phone line (no comments about this, please,
> Kate!)
4.4 kbytes/sec from a V.90 modem would be great, if you were to get it.
But bear in mind that when Netscape or an ftp client reports throughput
it's reporting bytes received which is inflated by compression. I connect
from home with a 28.8K modem which has an absolute max. throughput of
2.88kbytes/sec yet I ofetn see download speeds of nearly 4kbytes/sec
reported, when I'm downloading compressible data.
But enough of this - I'm going to have 45Mbit/sec from 1 November - the
nice lady from Genesis told me so on the phone today - all I have to do is
pay 12 quid a month and have a little interface device in my house which
overrides my modem and away I go - I can't wait :-)
Regards,
Niall O Broin
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