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Author Topic: Another strange ritual ?  (Read 2017 times)


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Another strange ritual ?
« on: November 12, 2012, 11:20:01 AM »


This is an extract from our website from a benighted resident with a VDSL sub 5 Mbps BT wholesale estimate, being ordered via PlusNet:-

The notification included the following puzzling paragraph: “When the engineer completes the work you may not experience fibre speeds straight away. This is because we need to manually adjust your speed profile when the order completes, so the change should be effective within 48 hours. Please be patient with us whilst we do this for you.”

Has anybody got any clues ?

Kind regards,



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Re: Another strange ritual ?
« Reply #1 on: November 12, 2012, 11:37:26 AM »

Not sure, but it could be to do with the fact that Plusnet users have a 'Plusnet profile' which is supposed to closely mirror the IPprofile.
Therefore it may take a while before the Plusnet profile updates from the BTprofile report?
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Re: Another strange ritual ?
« Reply #2 on: November 12, 2012, 12:37:22 PM »

When I had FTTC installed back in June 2011, it certainly was the case that Plusnet's own profile (a.k.a. Current line speed) had to be manually updated for FTTC services.

From Plusnet's Member Centre (need to be logged in to see it):-
What does "Current line speed" mean?
The speed shown above is based on your sync speed. This is always a little higher than the speed at which data will actually be downloaded over your broadband connection.

It took roughly 1 hour for my connection's profile to be updated, which really surprised the engineer as he saw 35Mb on his JDSU at my master socket, yet only 1Mb throughput on various speed tests (my previous ADSL profile).

He wasn't aware that Plusnet did this manually as all his other installations (Infinity) saw FTTC speeds instantly.
I convinced him that was the case & he said he would mention it to his colleagues, just in case they came up against the same thing with users that also might not be aware that some ISP's especially Plusnet did have to increase profiles manually.

Plusnet's profiles were initially set at 37Mb for 40Mb services & later at 20Mb (unlimited) for 80Mb services.

Until quite recently, that was still the case.

Nowadays, BT are supposed to issue a delta report to Plusnet each time a connection syncs, to ensure an appropriate profile is applied (slightly lower than BT's IP Profile), to avoid packet loss etc. due to attempting to provide more data than a connection can actually handle.

This doesn't work as intended as quite often, "on the fly" resyncs are too quick to initiate a new PPP session, therefore BT's IP Profile is NOT updated, leaving the user with a "stuck" IP Profile & a "stuck" Plusnet profile.

My connection's current sync speed is 28.18Mb, since an "on the fly" resync of 10th November.

BT's IP Profile (BRAS Rate) is 27.28Mb & my Plusnet Current line speed is 27.2 Mb.

I didn't notice when my Plusnet profile was adjusted this time, but it has previously taken a few days, especially if a new PPP session has not been initiated, either manually or automagically forced via the ROUTER.

I queried the "advantages" of using such an "unreliable" system a while back & this is the Plusnet response:-

My main point in response to this is that each resync of your BT modem will cause a new IP profile to be calculated as per the 96.7% rule and DLM quantisation process.  Each sync event should also generate a delta report for us.

In practice we are aware that this doesn't always happen every time.  This is concerning from our perspective as it has the potential to take up bandwidth from our network end points unnecessarily.  As such our business improvement team are working on a project with our BT wholesale relationship manager at the moment to feed this back in to the relevant channels BT side.  It's not something I play a direct role in but am aware that this is under investigation with the right people on both sides.

At this stage there isn't a great deal to do to influence this but rest assured that we are working on problems like this on a daily basis.

« Last Edit: November 12, 2012, 12:56:41 PM by Bald_Eagle1 »