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Max up to 8Mbps product update
Wednesday 05 April 2006 17:20:00 by Andrew Ferguson

The Max product upgrades are continuing, with BT Wholesale looking to manage up to 360,000 regrades every week. These regrades slots are portioned out to the service providers according to the number of customers it has, which explains why some are staggering the regrades rather than doing all the regrades in one go. Some providers may also be waiting for the bulk regrade tool to appear from BT Wholesale which is expected later this month.

The problem of people having a line syncing at a high speed, but downloads remaining stuck at 2Mbps continues, though some have seen improvements. We mentioned this in our news yesterday. The 2Mbps limit is due to the Data Rate which is set in the BT Wholesale network, and not by the DSLAM or your ADSL modem. In theory this should alter to a value close to your line sync rate within 75 minutes of the regrade and your hardware syncing at the new Max speeds. Alas this is not always the case, and a lot of people are seeing it take up to three days for the Data Rate limit to improve.

We believe the definition of 3 days is actually you get the regrade on day 1, stats are collected, day 2 you continue, and day 3 once the stats are in it will alter the Data Rate. In short the monitoring systems wait until three separate dates are seen before adjusting the Data Rate, that is if the 75 minute period did not alter your Data Rate.

One other point worth bringing to peoples attention, is that the BT systems do not set a maximum line sync rate, this is purely negotiated between the DSLAM and the ADSL hardware you have. Therefore if you do something like change your wiring to improve your noise margins you will see the line sync change the next time you re-sync the line. If your sync rate changes then you will have to wait for the Data Rate to catch up, which if the higher line rate proves stable it will do over time. If for any reason the line drops sync due to excessive errors the DSLAM and modem will retrain to a lower line speed to provide enough margin to maintain a stable line.

The retraining process outlined above should not happen constantly, but there are some people who due to various reasons may see their service reconnect at the same line sync rate after it has dropped, and then drop again within a few minutes. In these situations once the BT monitoring systems have seen a number of retrains (believed to be more than 10 retrains) due to line errors in a 24 hour period they will switch on interleave mode (if the option is set to AUTO - the default) and/or increase the target noise margin. Increasing the target noise margin will force the ADSL hardware to sync at a lower sync rate, which will then hopefully be stable. If your line is still very unstable after a 24 hour period then it is worth contacting your ISP's support line, to report it.

We have attempted to be as accurate as we can to the situations people are seeing, and what the BT systems do. If this information proves inaccurate or needs tweaking then we will update this news item, or release a new one.

Service providers are issuing various question and answer lists for their customers, and our forums now have a number of 'sticky' posts providing further information. Some posts people may want to read are:

Where information has been posted by ISP staff, be aware that some issues such as queues for the regrades may vary between service providers.

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