| Internet stuff
Cable is a local loop and as such can congest within the loop like an Ethernet ring, which will have collision issues; cable is symmetric but due to the local loop design download and upload traffic can contend
ADSL is asymmetric in the copper pair therefore download and upload have different channels, as defined by the spectral management plan. ADSL is sensitive to the length of the copper pair (Phone Line), cross talk (Line Noise) and local AM radio sources ( XMAS Tree light switchers etc..)
Fibre to the home is very new and much still has to be learnt about termination of fibre in the home in small low voltage reliable termination devices; the next stage is really fibre to the roadside cabinet (the green box) AKA VDSL; this effectively extends the exchange to the roadside box and shortens the copper pair, plus there is a different spectral plan involved known as ADSL 2+ which allows potentially higher download speeds subject to copper pair conditions.
All the above systems will be affected by the amount of bandwidth the ISP purchases from the exchange to the ISP interconnect point and again from the interconnect point to the ‘internet’.  |