I don't really see how he is wrong.

AFIAK BT use 10gigE symmetrical to the cab. Which has 288 users tops. So that works out 34.7mbit/sec each (up/down).

So the upstream is totally uncontented.

The downstream could be contended. This is incredibly unlikely. Considering not everyone will either be able to get 80mbit/sec (due to line length issues) or they may well subscribe to a package that is only 40mbit/sec, it would take nearly 100% of the cab to be downloading at full pelt all at the same time. It is is pretty much as close as 1:1 contention as you can get. Not to mention that it is unlikely for the cab to be 100% full all the time.

Virgin's DOCSIS network on the other hand maybe has 1gigbit down and at best 100mbit/sec upload to share between 400-500 users. The contention is probably 20x worse on the downstream and 50-100x on the upstream than BT FTTC.

This doesn't even address the fact that BT could easily add another 10gig/sec to the cab with a cheap hardware investment at either ends, vs the extremely expensive road digging than Virgin needs to do to add another UBR.

Edited by mr_mojo (Mon 31-Mar-14 06:18:53)

Very rusty, since a port was a physical port on a line card and only one line can be plugged into it.

VDSL2 - FTTC

Dedicated copper line to the cab - cable the coax is shared
GigE or more backhaul from cabinet to the fibre exchange.
This link has an assured rate of 15 Mbps or 30 Mbps (40 and 80 products respectively)
So yes contention can appear on this link of the fibre
At the exchange fibre connected to either BT Wholesale, Sky, TalkTalk or Zen hardware and then backhaul network
At this point what happens is down to each provider

The reason you generally get less issues than on DOCSIS is that the speeds are lower in comparison to the amount of shared bandwidth available

Normally 1 GigE, never seen anything to say 10GigE is used, multiple GigE maybe.

Are you sure? That seems pretty short-sighted. 10gigE fiber cards only cost a few £100 more than gigabit ones.

Might have the links set to 1gigE and add more virtual links at 1gigE? Seems bonkers to be adding multiple cards when 10gigE is so cheap now.

Edited by deleted (Mon 31-Mar-14 12:46:00)

GigE is what I believe is used and http://www.coolwebhome.co.uk/fibre-cornwall/images/f... shows you an optic plugged into the DSLAM

So upgradeable. Spending a few £100 more might be seen as wasting public money and when you are installed 1000's of cabinets a few hundred makes a difference.

"Which has 288 users tops"

So it is shared?

AFAIK fibre cable can handle hundreds of simultaneous transmissions.

Edited by broadband66 (Mon 31-Mar-14 13:37:44)

They dont have a fair usage policy no.....

But i rang up to speak to someone about 3 weeks ago about a problem and the bloke on the phone kind of insinuated i was a heavy user and stated that for the past 3 months my average downloads have been around 110GB a month.

Well there would not be 288 individual fibres back to the exchange for each person connected to the DSLAM would there, or is that what people expect?

Fibre Optic can do terra bits per second with the right optics at either end.

The 288 is down to the number physical line card ports that the DSLAM in the cabinet can support

http://www.coolwebhome.co.uk/fibre-cornwall/images/f... and
http://www.coolwebhome.co.uk/fibre-cornwall/images/f...