On 12/01/11 23:15, Lisi wrote:
> So what would you have me call them to distinguish between whatever goes over
> LLU and what one can get on BT lines in a non-updated exchange? (I.e. one
> with a maximum ADSL speed of up to 8MB.) The speeds are completely
> different.
Firstly, let me state that I am not an expert in telecoms, I'm only
regurgitating what I think I understand to be the case. LLU has got
nothing to do with ADSL per se, it is an acronym for Local Loop
Unbundling. This is a regulatory thing, best read up on it on Wikipedia
[1] to properly understand the nerdy bits behind it. Other telecoms
companies here that has LLU arrangements include TalkTalk, Tiscali and
others. Most companies however simply re-sell BT Wholesale products at
cheaper rates than BT's retail pricing.
What you might be referring to from a speed perspective are the
different ADSL standards in use today. "ADSL Max" is a service and
standard developed by BT (I don't know of any other country that has
it), and it is re-sold by a lot of smaller ADSL service providers. ADSL
Max typically offers speeds of 8Mb/s downstream, and 448Kb/s upstream.
The new kid on the block is "ITU G.992.5", better known as ADSL2+. This
have downstream speeds of currently up to 24Mb/s and upstream speeds of
1Mb/s. I'm not sure how prevalent ADSL2+ is, since it is quite new (it
was only introduced in my local exchange less that 12 months ago). From
what I can suss out, ADSL2+ providers typically have their own LLU
arrangements, meaning that they are in full control of that last little
bit of kit between the local exchange and your phone socket. Please
don't take this as "telecoms gospel", it is quite possible that I don't
know what the heck I'm talking about! ;-) I find the industry to be a
rather complex beast.
In short: Where ADSL is concerned, ADSL2+ is the way to go. There are
other connectivity options around - cable is interesting (speeds of up
to 50Mb/s downstream), but we only have Virgin Media offering it as far
as I know. Optical fibre seems to be making an entry into the consumer
market, which is about time (places like Singapore, Hong Kong and Japan
had it for years). Fibre optic speeds can easily go into the gigabit
range. It is also fully synchronous in terms of speeds (same speeds
upstream and downstream), since it is treated in the same way as normal
ethernet. Both BT and Virgin have fibre offerings, still rather pricey
at the moment, but certainly attainable if you really want it.
Links:
[1] LLU definition:
http://en.wikipedia.org/wiki/Local-loop_unbundling
--
Regards,
Jan Henkins
