Quote:
Originally Posted by General Maximus
with regards to Infinity, I think it was qas who pointed out the other day (too tired to go and look back) that the worst it can possible get is a 5:1 contention ratio,
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That was just the upstream, though those numbers were an understimate. Each cab gets multiple dedicated gigabit links to the headend (not just one), with BT putting in more as needed to maintain a (almost) guaranteed minimum speed of 30mbps per 80mb customer. The worst-case scenario on the downstream would be a fully-loaded 128-line cab with every user on 80mb and 2Gbps of backhaul, still only 5:1 contention on the downstream and 1.25:1 on the upstream, assuming they don't light up the extra fibre as promised.
But that's just cab to exchange - what happens at the exchange and how contended the BT Wholesale pipe is is up to the ISP. Contention issues on BT usually happen at the exchange and Wholesale pipes - those are limited by how much an ISP wants to pay for how much capacity. ADSL lines are 100% uncontended from exchange to user, yet there are plenty of congestion issues on BT ADSL