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MaxDSL and Line Drop Info from another ISP


MaxDSL and Line Drop Info from another ISP


"DLM: Dynamic Line Management
Because the parameters needed to get the most from a line depend on the line itself, they need a little fine tuning. BT have a range of ADSL profiles they can apply, as described above. These allow interleaving on or off, along with a margin of 3dB, 6dB, 9dB, 12dB, or 15dB of noise margin. The default is 6dB without interleaving

If the line syncs at a level where it is trying to work too fast for the line conditions, the modem will give up and re-sync (trying again). Every time the line syncs at a different rate BT notice. If the line syncs a lot then Bt will change the profile.

The process can be time consuming. One of the rules is number of re-syncs inan hour, with a very fast change in profile, but others are number of resyncs in a day, and a new profile applied the next day. It can take several days for the line to eventually settle at the right rate.

BT will normally apply interleaving if there are errors on the line, but we can over-ride this forcing interleaving on or off, or leaving it to BT. To change this takes us one working day though.

Eventually the line should reach a level where the margin is sufficient for a reliable service. This may mean the line syncs at a higher speed initially, but is unreliable, and after a few days it syncs at a lower rate and is stable.

Because the profile set is not a specific speed, but a margin, fixing any problems with internal wiring, or getting a better modem, can mean the modem syncs at a higher speed right away. BT say that they can also spot a line is good quality now, and adjust the profile back to a lower margin, but this takes many days and the exact algorithm is not clear.

BT are also planning to monitor the corrected errors when in interleave mode. The way this works is that errors can be detected and corrected, hence making the service work in the face of some interference. However this also provides stats of how many errors were corrected, and so allows BT to see the line is now clean and interleaving is no longer necessary. They plan to have a system to remove interleaving automatically in such cases.

Important: The DLM process is continuous. It is not just for the first 10 days, or some such - it applies to the line all the time. It is also important to realise that whilst we can control interleaving, we cannot set a specific DSLAM profile via BT"

If other ISP's can explain this, then why can't Plusnet? No matter how many times my line drops, my BRAS is stuck and will not update my noise margin from 6-9, nor will it put interleaving on my line.

Even when I manually force resyncs - as many as 20 in a row, I cannot get the BRAS to update my profile, as it should.
Posts: 381
Registered: 06-04-2007

MaxDSL and Line Drop Info from another ISP

A neat explanation - thanks for the link Smiley

I was particularly interested by the apparent dismissal of the so-called 10 day period as a myth. Perhaps 10 days was regarded or touted as some sort of expected average at some point, but that description does seem to bury it.

Good luck in getting your line sorted out, and I hope it's fixed sooner rather than later. :?

MaxDSL and Line Drop Info from another ISP

I got more clarity and understanding from reading that than I have in weeks of trawling through posts on here and raising tickets.

MaxDSL and Line Drop Info from another ISP

Yes well glad it helped. I just hope CS or tech support in PN read it, because at the moment they seem clueless.

MaxDSL and Line Drop Info from another ISP

Clueless?? Tell me about it!! 45 days i have had a fault raised with plus, no avail!!

Line speeds vary from 1.2Mb to 2.3Mb, with my Tx rate which was around 480kbps, is now 288kbps.

They have absolutely no idea. They asked me to conduct BT speed tests on my line.... I'm on LLU, the tests don't work on LLU. Idiots.

45 Days of crap speeds, disconnects and pure frustration have led me to seriously consider moving to another ISP. I have had my line tested, and it is capable of supporting 6.5 to 8Mb.

Good luck with your problems..... :shock:
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

MaxDSL and Line Drop Info from another ISP


Thanks for posting the link, I don't think there's anything in that which we didn't know already, but it's still a useful read. Andrew's and Arnold have been one of the ISP's that spend a huge amount of time working with BT Wholesale on improving the faults process (anyone that's read about the long grass problem will be well aware of what they've done) so I would expect them to have a lot of info on Max.