From another Newsgroup:

Moved to unlimited last November still getting 1Mb. Lies from Tech Support.

Now Orange are saying LLU server in exchange is what is limiting the speed and that they have no idea when it will be upgraded to offer faster speeds.

Exchange is Netherley in Liverpool.

Keith

Aside from the marketing question, there are some interesting operational & product issues around migrating customers from IP-Stream to LLU.

One part of the decision to not upgrade to IPstream Max could be around the speed of each users connections. Aside from any interopability issues between different makes of modems/DSLAM etc, the IPStream Max product is actually very good at giving you the highest line rate possible. The reason for this is BT put all customers on an initial target signal/noise level of -6dB, which is quite a narrow margin, but results in a good line speed. The main reason BT can do this is they built a system called DLM (dynamic line management) which watches every connection and looks for instability. If DLM spots a line is flapping or retraining lots, it pushes the target margin up a notch to -9dB, which will reduce the speed but makes the connection more resistant to occasional noise.

LLU providers have a problem, as building a DLM system is very expensive, so you either put your customers on a target -6dB, get more faults than you want and manually up the target margin, or you put all customers on a more conservative -9dB, have a lower fault rate, but risk upsetting the customer as their speed on LLU is likely to be lower than it was on IPStream.

Each LLU provider has made its own decision regarding this, and I have no idea about what Carphone Warehouse have done, but the above might be a factor.

"LLU providers have a problem, as building a DLM system is very expensive"

I thought LLU providers didn't have quite the same need for DLM though, owing to them having (effectively) pure-IP networks all the way from DSLAM to Internerd, without the PPPoA bits which IPstream Central implementation requires, which (being ATM) have bandwidth constraints on them which don't apply the same way in a pure-IP network. Hence 21CN etc (no visible ATM).

In the early days of LLU they also had another reason for not needing DLM; they could have a spreadsheet which had an exception entry for any punter whose line didn't work well at the default target margin, and some means of replicating that data from punter to TS to database/spreadsheet to DSLAMs as required, e.g. Post-Its (ask any early Bulldog LLU punter ). That kind of operational process doesn't scale well to millions of punters though, so some better integration/automation is eventuallu needed to achieve the same result.

Sometimes these exception entries were a revised SNR margin, but based on what I've seen/read, the more sensible approach was a "capped sync speed" which made it all the stranger when BTw's Rambo stuff ignored the "capped sync speed" approach.

I suspect another reason for LLU-centric ISPs not rolling out Max might be because it would require a significant ongoing extra spend on additional Central bandwidth to produce any noticeable increase in punter-perceived performance. Max typically doesn't produce any extra revenue for any ISP to cover any extra spend on Centrals, but the LLU-centric ISPs, largely competing on price, are particularly sensitive to money going to BT.

The capped sync speed approach was more because in the early days there was quite poor interopability between some DSLAM and some very popular CPE (I shall name no names!), where for some reason the modems didn't retrain if the margin became too low. This would result in connections that would hang, and the only way to kick them going was to hard reset (generally done by rebooting the CPE or pulling the DSL cable)

The answer to this was to cap the connection speed to a speed low enough to ensure you rarely needed to retain, but that is a very crude fix of the symptom, nothing more. DLM is the most elegant solution, but in a big roll out requires tracking the status of millions of ports which is a big job.