Here is a bit more information about the noise margins/signal to noise ratios on BTW Wholesale Broadband Connect ADSL2+ . When an ISP orders one of these circuits the default broadband profile is 160K-24Meg 6dB downstream SNR 6db upstream SNR with no interleaving applied .The exception to this is that "short" lines (typically less than 800m) which have a 3dB SNR downstream. In the first 10 days Dynamic Line Management will attempt to settle on the best combination of parameters to give stable service. This includes setting the downstream SNR between 6db-15db ( 3dB as the lowest downstream SNR on a "short" line), applying varying degrees of interleaving upstream and downstream if the end user has not opted out of interleaving. The stability level of the circuit chosen by the ISP comes with triggers based on the number of retrains in 24hours and how many errors appear on the circuit and these are acted upon by DLM.

There are in excess of 380 possible broadband profile combinations for BTW WBC ADSL2+ .

DLM operates whenever conditions change on a circuit. One way to drop your sync speed to 288kbps is to switch your router off every night. DLM responds to the loss of sync by changing the profile by increments in a vain attempt to keep the circuit up.Over time DLM will arrive at what is called a chronic banded profile 160k-288k. If this behaviour is identified by the ISP in discussion with their customer and the customer leaves the router on , the ISP - EE included - can change the broadband profile. BTW have made available to ISPs a management tool called Customer Controlled SNR . CCSNR sends a batch request to the BTW Network for a profile change to the broadband port in the exchange. If the request is successful this also triggers a 10 day MSR/FTR recalculation period. Once this is triggered the ISP cannot make another profile change to the circuit for 10 days. The batch request will fail if there is already a recalculation period in progress - this could be because BTW have changed the profile or it has been triggered by the closure of a broadband engineer fault task where there has been an improvement to the BTW Network.

There is no restriction on BTW changing the broadband profile as they have their own tool to do this which is most definitely not available to ISPs. Their tool has a couple of refinements to fix broadband profiles which only tend to be used on a last resort basis.

So yes it is true that EE can change the target NM/downstream SNR and increase the available bandwidth to maximise the downstream sync speed. BUT it has to be done responsibly. DLM works more or less instantly. If a circuit is unstable and nothing is done to rectify this, running a CCSNR request is a waste of time.

There was a culture in Orange/EE that low downstream SNR = fast broadband regardless of how poor the line carrying the circuit was, and requesting a CCSNR was most often done to pacify angry customers.
There was also the habit of setting a 3db downstream SNR on long lines to try to squeeze more bandwidth out of the line but the problem with this is that it put the broadband signal closer to the inherent background line noise - any line noise spikes would then result in an unstable circuit and the customer complaing of slow speed became the customer complaining of a dropping connection.

So believe me when I say nobody in EE sits there all day "capping" and banding customer circuits. DLM is quite happy doing the management of circuits which could end up with a banded profile.
What needs to be done is full diagnostics on your circuit to identify and eliminate things that make your circuit unstable and trigger DLM to alter your circuit profile. This would include full home environment checks, analysis of the Network data collected on the exchange for your circuit and quite probably investigation by either a PSTN or a broadband engineer.

Again you need to be persistent with the EE Tech Support Team to get the fault investigated properly.

Please explain how turning a router off every night reduces the sync to 288 Kbps?

Why should one sync in every 24 hours be considered a sign of a line that is so unstable that it needs pushing down to 288 Kbps.

Dubious exposition! There are at least 3 falsehoods in it which casts doubts on the rest of it, altho' the actions of the DLM is in general about right.

In reply to a post by Narayan:

The exception to this is that "short" lines (typically less than 800m) which have a 3dB SNR downstream
....
( 3dB as the lowest downstream SNR on a "short" line),

How does this account for my "medium" line, 26dB attn. 2km length, having a 3dB target NM for years?

One way to drop your sync speed to 288kbps is to switch your router off every night.

Perposterous! I switch router off every night and maintain my 20 Meg stats every day. You need to interrupt it more frequently than that to damp the speed and even then it won't go down so low. The DLM is not such an idiot!

CCSNR sends a batch request to the BTW Network for a profile change to the broadband port in the exchange.

Is the request for a particular NM or a min. NM?

So yes it is true that EE can change the target NM/downstream SNR and increase the available bandwidth to maximise the downstream sync speed.

It is more true that EE can increase the target NM/downstream SNR and decrease the available bandwidth to minimise the downstream sync speed as they are in a habit of doing as many threads here attest.

requesting a CCSNR was most often done to pacify angry customers.

No, often the CCSNR was forced on the line from initial connection, as it was to mine, and it was only removed, or relaxed, in response to persistent customer complaints.

There was also the habit of setting a 3db downstream SNR on long lines to try to squeeze more bandwidth out of the line

No, the habit is to set unnecessarily high NM presumably to over-stabilise the line to reduce support calls from pesky custs who might have got discons.

So believe me when I say nobody in EE sits there all day "capping" and banding customer circuits.

I do believe you! They don't sit and do it all day; just at the start of a cust's activation.

What needs to be done is full diagnostics on your circuit to identify and eliminate things that make your circuit unstable

My line does not need diagnosing as it is running at an extremely stable 20 Meg Sync @ 3dB NM.

Finally, how is all this this affected by Orange not being a true BTw ISP, but just a reseller of the BTw White-Label products?

The logic built into DLM is that the prevailing state of a circuit should be in synchronisation. With the router off DLM works on the assumption that it is interference on the line/circuit that is preventing the router from completing a handshake with the broadband equipment in the exchange and establishing sync. As this is a repeated event, gradually over time, DLM tries to move the downstream broadband signal on the line away from the supposed interference by increases in the downstream SNR, in steps from 6dB through to 15dB and beyond that into banded profiles based around the normal sync speed, then narrowing the bandwidth spectrum until ultimately it reaches the lowest chronic banded range of frequencies which will only allow speeds betweem 160k-288k. I must emphasise that it takes time to get to this point. However there are plenty of customers who report slow speed and the initial check shows a chronic banded profile. In diagnosing such a fault you would look at the Local Access Data provided to ISPs by BTW. Typically you would see % uptime (i.e. circuit in sync) of 50% or less. Bear in mind that is is an average and you would then drill down into the Local Access Data and look at the 14 day history - 24 hour data graphs and see the downstream speed etc. which is only recorded when the circuit is in sync. You then ask the simple question - do you switch the router off when not using the broadband. The customer says yes and you ask when did you notice the circuit getting slower , and they say it's been getting slower for a couple of months now. The fix is a bit of education about DLM and most of these types of customer will be happy to leave the router on. The ISP can then with some confidence run CCSNR and get the circuit back on the standard broadband profile.

This happens with some customers and they tend to be infrequent or low users of broadband.


However by far the largest number of faults where DLM has applied chronic banding are due to circuit instability and can happen within very short timescales.

Well when i next see a line stuck at 288kbps sync I will let you know

My estimation, given the poster's explanation, is that there will be several hundred thousand, if not a couple of million, given the fact that every BT Wholesale-based broadband user I have met in the real world turns their router off when not in use. So at least once a day, and often more than that.

Strange that none of them have mentioned poor speeds to me.

Imagine what would happen if someone turned off their router whole on holiday for a fortnight.

Very strange dlm to assume no data when turned off equals bad line

No need to imagine ! I did whilst I was in Spain late May - early June. I was shocked to find when I got back & booted up that I was still syncing at 20 Meg with the usual stats.

maybe its a special EE system, they did when signing with BT Wholesale say it was different and not just a white label job