[Gllug] Old type versus new ADSL?

[Jason Clifford]

On Wed, 2008-03-19 at 17:11 +0000, MJ wrote:
> What is the benefit of old type services with an ISP?
> The new bandwidth fluctuates I guess in order to provide always on?

There are 3 classes of ADSL in the UK at present.

ADSL
ADSL MAX
ADSL 2/2+

ADSL and ADSL MAX are based upon the same standard and run at up to 8Mb
however ADSL is sold at fixed rate speeds of 256kb/s, 512kb/s, 1024kb/s
and 2048kb/s (although 256kb/s is not offered by many ISPs) while ADSL
MAX is rate adaptive up to 8192kb/s sync rate which translates to about
7.1Mb/s maximum speed.

The ADSL MAX rate adaptive service generally works better for most
people as it provides faster speeds and reacts better to changing
conditions on the line. With Legacy ADSL (as we call non MAX ADSL) you
have a fixed sync rate which means if conditions on the line drop below
those needed to sustain your sync rate you lose service rather than just
having a drop in speed.

ADSL 2/2+ is currently only available from LLU providers. That will
change in about 8 weeks when any ISP using BT wholesale services will be
able to offer it where the exchange has been enabled for it. ADSL 2/2+
offers headline speeds up to 24Mb/s however very few people will see
anything like that. We're taking part in the current first stage trials
on BT based ADSL 2/2+ at present and the highest speeds seen are about
21Mb/s. It's hard to give any worthwhile answer as to how well ADSL 2/2+
will run as the first stage trial is too small.

Jason

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