On Mon, 07 Jul 2008 15:33:33 +0000, ato_zee passed an empty day by
writing:

Have you seen what 1% (let alone 10% or 30%) packet loss does for TCP
throughput?

I've not seen it - what does it do? I'm guessing it has a serious
throttling effect.

So ethernet cannot work as it is based on collisions, retransmissions,
and packet loss.
Try using a heavily loaded ethernet segment to see its effect on TCP/IP,
preferably while watching a network analyser, to see what's happening in
real time. Ideally you aim for a 1% or less figure for retransmissions
over any link, at 10% you notice degredation, 30% or above severe
degredation.
This applies to ADSL as well.
For gamers, VOIP, P2P you try for a low error rate, but have to bear in
mind that a connection is only as good as the weakest link, that usually
means the slowest most congested link of the many point to point links
you may be going through, from router to router, often between
continents. If you want low loss then you use a synchronous protocol,
but you would still have problems with some UK ADSL long, high noise,
lines.

AFAIK ADSL does not use Ethernet - it uses point to point protocol over
ATM (or mostly in the UK it does). Not sure, but is that not layer 2?
That would mean there could be no packet loss as it is moving frames? My
guess would be that if you pack a frame with packets and it has to keep
resending the frame, throughput could be seriously hampered. It is,
however, just a guess. The PPP portion should already be able to
negotiate the optimum connection - it always could with dial-up modems.
How it fits in with Asynchronous Transfer Mode has me too cuffudled to
get my head around at this moment.

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