cancel
Showing results for 
Search instead for 
Did you mean: 

Turn off DLM

Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Turn off DLM

Please turn off DLM on my line, and set downstream target SNR to 6dB, set upstream target SNR to lowest value possible, and turn off Interleaving.

17 REPLIES 17
Highlighted
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 1,325
Fixes: 63
Registered: ‎09-10-2018

Re: Turn off DLM

HI @bbpn, thanks for your post.

 

We're of course happy to amend these settings for you - but can you confirm if you're experiencing an issue that you believe will be resolved by these changes?

Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Re: Turn off DLM

Hi @OskarPapa ,

Thank for your quick reply.

There isn't an issue, I just want to optimize the connection based on the statistics on my router, e.g. reduce error count by increasing SNR and increase speed for the direction with very low error count.

Highlighted
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 1,325
Fixes: 63
Registered: ‎09-10-2018

Re: Turn off DLM

Hi @bbpn,

 

Apologies - I mis-advised in my initial response, entirely my fault and I'm sorry for this.

 

After turning off the DLM, my colleague @Gandalf (the hero-Wizard of the Community) has informed me that under no circumstances should we be turning off the DLM and that we would not do this for any other customer moving forwards as it can cause major issues on a line.

 

It's up to you - we can either turn it back on for you on Monday AM (we need to wait a minimum of 24 working hours) or leave it switched off but I do need to make you aware that if we do switch it back on then we would not be able to fulfil any further request to remove it.

Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Re: Turn off DLM

Hi @OskarPapa ,

I would like to keep DLM turned off, I don't think it's been turned off as my router hasn't resynchronized. @Gandalf a couple of weeks ago mentioned in the post below that Interleaving and target SNR could be manually set. Has the policy changed since then that we can't do it any more?

https://community.plus.net/t5/My-Order/Broadband-and-phone-to-be-switched-on-different-dates/m-p/166...

Highlighted
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 1,325
Fixes: 63
Registered: ‎09-10-2018

Re: Turn off DLM

Thanks for your reply @bbpn.

 

Has the policy changed since then that we can't do it any more?

No not at all - We're able to manually set the SNR, without disabling the DLM.

 

I've just manually killed the PPP session, however, a quick reboot is going to probably be needed to force the change through.

 

The best option really would be to leave the DLM on, set the SNR to the level you need and set interleaving to off.

Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Re: Turn off DLM

Hi @OskarPapa ,

Thanks for killing the session, my router has resynchronized. I only wanted to set SNR and Interleaving, I thought DLM had to be turned off to do that. There's conflicting information about how DLM works with the manual Interleaving and SNR settings.

According to @Gandalf , manual settings can be set permanently that overrides DLM, according to other staff members like in the post below, DLM needs to be turned off for manual settings to stay put, in that same thread, another user was under the impression that manual settings could override DLM. I'm confused. Could you double check how manual settings work with DLM? If manual settings could override DLM, what's the advantage of having DLM when manual settings are used?

https://community.plus.net/t5/ADSL-Broadband/Turn-off-Interleaving/m-p/1669930#M333780

Highlighted
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 1,325
Fixes: 63
Registered: ‎09-10-2018

Re: Turn off DLM

Hi @bbpn, thanks for getting back to me.

 

I've discussed this at length with @Gandalf and the bottom line is that we can send a modify order to our suppliers to have them turn interleaving off permanently and to change the threshold that the DLM uses in order to make its decisions. This should then prevent the SNR target from dropping below 6db. (It may go up)

 

We can also email BT if needed to have them pin the SNR target to a certain level, although despite the term pin, that's not guaranteed and it could still change.

 

Hope this helps to clarify things.

Highlighted
Community Veteran
Posts: 5,434
Thanks: 626
Fixes: 25
Registered: ‎10-06-2010

Re: Turn off DLM

P.S. Nobody can manually set any SNR. There is no such thing as "target SNR". It's target SNRM, SNR Margin. SNR and SNRM are not the same.

Highlighted
Plusnet Help Team
Plusnet Help Team
Posts: 17,513
Thanks: 5,446
Fixes: 921
Registered: ‎21-04-2017

Re: Turn off DLM

@ejs thanks for the clarification. While I don’t think it really changes how we work, it’s good to know. 

@bbpn I thought I’d pop in to expand on what @OskarPapa has said as I think there’s a bit of confusion on the thread you’ve linked.

We can change the downstream SNRM target between 3dB, 6dB, 9dB, 12dB and 15dB. The lowest the upstream target goes to is 6dB.

DLM can override any changes we make however we can influence DLM in its decision making by setting a custom threshold, the most common one is when DLM drops the SNRM target down to 3dB continually and the line cant handle it. 

So we place what’s called a modify order to set a threshold to ‘trick’ DLM into thinking the line can’t do any better, keeping it at a minimum of 6dB. 

The default threshold is ‘Standard/Speed’ which means DLM will favour speed > stability. Other thresholds are ‘Stable’ and ‘Super Stable’, which is the other way around, stability over speed. But in this instance, I usually set a custom one.

We can also email our suppliers to ‘pin’ although the correct less commonly used term I believe is ‘hard set’, the SNRM target at a particular value. 

DLM may still increase it beyond 6dB if absolutely needed, for example if your connection starts dropping out heavily as it’s better to have a slightly lower speed than no connection while the underlying problem is being investigated.

If your service is provisioned with interleaving as ‘Automatic’ (Normally by default) then DLM will toggle it on and off as it sees fit and we can also adjust it using the DLM self service repair tool. 

Through placing a modify order, we can change the way interleaving is provisioned switching it on or off permanently. This will keep DLM switched on but it won’t affect interleaving. 

So if you’d like interleaving off and an SNRM target no lower than 6dB, I’d recommend we do the following:

  • Place a modify order to switch interleaving off and alter the threshold to a custom one. These two actions can be done together and go through within 1 working day
  • Switch DLM back on
  • Change the SNRM target to 6dB if it isn’t already and email BT to hard set it at 6dB

Even though it is technically possible for us to switch DLM off, I think the above is much better as sometimes DLM needs to intervene. I’ll admit I don’t know what will actually happen in the long term if we leave it off. It’s my understanding from when I first started here that switching it off would ‘break’ the line although that may have been an over-exaggeration and it likely would just cause a lot of issues if DLM does need to intervene. It’s not something we’ll start doing upon request.

I hope this helps. 

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Re: Turn off DLM

Hi @Gandalf ,

Thank you for your detailed explanation.

I'm currently happy with the downstream noise margin and Interleaving being off. I'm using a router/modem running OpenWrt which allows me to adjust downstream margin myself. My upstream margin is a little high, it's around 7dB, I started another thread to see if it can be reduced further https://community.plus.net/t5/ADSL-Broadband/Reduce-upstream-noise-margin/td-p/1674744

Highlighted
Plusnet Help Team
Plusnet Help Team
Posts: 17,513
Thanks: 5,446
Fixes: 921
Registered: ‎21-04-2017

Re: Turn off DLM

Hi @bbpn thanks for getting back to us. 

I've run a test on your broadband connection and while the SNRM target is at 6dB, the margin itself is 10.3 which is a lot higher than I'd expect. Just wondering have you increased the margin to this yourself?

I can see interleaving is switched off but to make sure DLM doesn't toggle it back on, I've placed a modify order to keep it off. Let us know if at any point you'd want interleaving again and we can undo this change.

Your upstream SNRM target is 6dB which is the lowest it can go, the margin itself as you can see is 7dB. I wouldn't expect you to see much of an increase in speed though with 1dB as the max upload sync speed you'd get is 1200kbps.

If you've not increased the downstream noise margin to 10.3, I'd imagine this may be linked to the high upstream noise margin and might be indicative of an underlying issue somewhere. The mean time between errors(MTBE) is also particularly low at 40 which means that in the last 24 hours your line has been erroring every 40 seconds.

Do you hear any actual noise on your phone line if you dial 17070?

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Re: Turn off DLM

Hi @Gandalf ,

Thank you for your reply.

Yes, I have increased the downstream margin on my end, I I asked to set downstream to 6dB, not because I wanted to sync at that level, but because that would give me room to both increase and decrease the margin depending on my needs. Currently I want a low latency connection, the increased margin would reduce error rate and therefore reduce retransmission.

When I tested 6dB downstream margin, my upstream margin was also high (error count was low).

I have just tried 17070 quiet line test, there's no noise.

I think my line would still be stable with 3dB downstream, but I'd sacrifice downstream speed for reduced retransmission.

As you noticed my upstream error count is low (much lower than 10dB downstream, even more so than 6dB downstream), that's why I want to decrease upstream margin.

Highlighted
Plusnet Help Team
Plusnet Help Team
Posts: 17,513
Thanks: 5,446
Fixes: 921
Registered: ‎21-04-2017

Re: Turn off DLM

Thanks for getting back to us @bbpn 

I'm afraid we can't move the SNRM target any lower than 6dB and we've no control over the actual margin. There'd likely be an underlying cause behind DLM increasing the noise margin.

Do you have a different router you can try and is your router connected into the master socket? Although ideally I'd recommend the test socket underneath the front faceplate which will rule out any internal wiring including the faceplate.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
Highlighted
Rising Star
Posts: 53
Thanks: 5
Fixes: 1
Registered: ‎31-08-2019

Re: Turn off DLM

Hi @Gandalf ,

I have many ADSL/VDSL routers, my current router is connected to the BT Openreach MK2 faceplate. I could try other routers with the master socket.

I thought DLM was turned off on my line, is it not the case? I have restarted my router quite a few times in the last few days while testing DS margin, would that have affected DLM despite having a manual margin of 6dB?