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Originally Posted by ianathuth
I think that you have to take account of both upstream and downstream bandwidth when you look at this. If you have an upstream channel on a UBR with 200 users on it and eight or ten 1Mb users are leaving their computers running on p2p with their upstreams being saturated by people downloading from them then those few can be using up 60-80% or even more of the available upstream bandwidth and slowing down the service for all users on that upstream card.
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Upstream is 256k per user 1 Mb user.
NTL claim a maximum (guaranteed !!??) contention ratio of 20:1.
So if these figure are true, contention starts with the 11th user (200 potential users / 20 = 10 users with no effect from contention)
So at this point let's imagine 10 (heavy) users online. That is 5% (of potential users) using 100% of the bandwidth, or 100% of 'active users' unsing 100% of the bandwidth - but at this point no one else is using it so it don't matter.
Lets add another 10 'light users'
So now we have 20 users all getting 128K upstream instead of thier maximum 256k. So now we have 'heavy users' representing 5% of potential users using 50% of the bandwidth, or representing 50% of active users using 50% of the bandwidth. we have the same for 'light users'
Lets add another 10 'light users' (so now we have 10 heavy users and 20 light users)
So now we have 'heavy users' representing 5% of all potential users using 33% of the bandwidth, or representing 33% of 'active' users using 33% of bandwidth. We also have the light users representing 10% of all users using 66% of the bandwidth, or representing 66% of the 'active users' using 66% of the bandwidth.
and so and so (just keep adding another 10 'light users' untill all 200 users are online at the same time)
So where oh where do these _constant_ claims from the telcos (and not just from NTL I might add) of 5% of users using 80% of the bandwidth come from?
Either I have barked way way up the wrong tree here, or someone is telling porkies. If it is the former then please please explain to me where I am going wrong ? In the absense of someone pointing out where my gross stupidity has crept in, in the above, I will stick to the view that there is a strong porcine whiff comming from the telcos.
(hey this is good stuuf. Anticap guys you should use this and you are welcome to if you like)
For more 'interesting reading' on the general topic have a look here
http://www.ntlhell.co.uk/index.php?a...=1&t=3083&hl=&