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Standard User WWWombat
(fountain of knowledge) Thu 18-Apr-13 16:27:09
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Re: DLM and the NTE Modem


[re: Alexir] [link to this post]
 
In reply to a post by Alexir:
Around the same time my new flatmate had arrived and (I just found out) has be running P2P 24x7, downloading up to 20gig per day. Could this be connected to DLM setting caps or am I barking (up the wrong tree)?


It certainly *shouldn't* make any difference - the bit errors ought to be happening and be being caught by CRC checks irrespective of whether the end-user is actually transferring data.

There is one way to check though. Turn it off. Possibly for up to a month....
Standard User StephenTodd
(committed) Thu 18-Apr-13 16:32:27
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Re: DLM and the NTE Modem


[re: WWWombat] [link to this post]
 
the bit errors ought to be happening and be being caught by CRC checks irrespective of whether the end-user is actually transferring data.
Are the cabinet and modem essentially in a continuous chat even if no user data is being transferred?

--
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.
Standard User WWWombat
(fountain of knowledge) Thu 18-Apr-13 16:45:18
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Re: DLM and the NTE Modem


[re: StephenTodd] [link to this post]
 
Yes.

The datastream is broken down into frames, with framing and control data forming the structure. The modems are constantly monitoring that data to ensure that it can hear the other side - which can lead to the "loss of signal" event and a resync.

The same control bits are used for the modem to report back to the DSLAM any errors that it is seeing.

They're all constantly going back-and-forth.

The gaps between the framing/control data is where the end-user data goes. If there isn't anything to send, it is just empty rather than non-existent. I don't have my VDSL2 spec to say what empty actually is though.


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Standard User ryant704
(regular) Thu 18-Apr-13 18:04:16
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Re: DLM and the NTE Modem


[re: WWWombat] [link to this post]
 
Yes, as wombat said loss of signal this will be formed under errors as UAS/SES I believe...
Standard User Andrue
(knowledge is power) Thu 18-Apr-13 18:15:57
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Re: DLM and the NTE Modem


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
The gaps between the framing/control data is where the end-user data goes. If there isn't anything to send, it is just empty rather than non-existent. I don't have my VDSL2 spec to say what empty actually is though.
Thanks for that. I thought it was something like that but wasn't sure. I suppose my comments about the modem cycling back on power and tones in use could still change the error rate though. Does VDSL2 do any of that?

---
Andrue Cope
Brackley, UK

Just because he could. RIP.
Standard User Alexir
(learned) Fri 19-Apr-13 14:52:30
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Re: DLM and the NTE Modem


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
In reply to a post by Alexir:
Around the same time my new flatmate had arrived and (I just found out) has be running P2P 24x7, downloading up to 20gig per day. Could this be connected to DLM setting caps or am I barking (up the wrong tree)?


It certainly *shouldn't* make any difference - the bit errors ought to be happening and be being caught by CRC checks irrespective of whether the end-user is actually transferring data.

There is one way to check though. Turn it off. Possibly for up to a month....


I did turn it off (that's to say stopped the massive P2P downloading) on 12 April. Now I know causation and correlation are not the same thing, but after a month of falling speeds the DLM cap removed itself today and I'm back to a full 38meg
Standard User RobertoS
(sensei) Fri 19-Apr-13 18:12:10
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Re: DLM and the NTE Modem


[re: Alexir] [link to this post]
 
I think it is possible that TalkTalk were doing the slowing down, not the Openreach DLM.

Which Openreach modem have you got? An HG612 or and ECI? It is possible with the HG612 to unlock it very easily, and then you can monitor the error rates to see if they change under heavy use. (This can be done with the ECI one as well but it'sa lot more difficult to unlock).

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.2/15.2Mbps @ 600m. - BQM

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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Standard User WWWombat
(fountain of knowledge) Fri 19-Apr-13 18:39:07
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Re: DLM and the NTE Modem


[re: Alexir] [link to this post]
 
In reply to a post by Alexir:
I did turn it off (that's to say stopped the massive P2P downloading) on 12 April. Now I know causation and correlation are not the same thing, but after a month of falling speeds the DLM cap removed itself today and I'm back to a full 38meg


I might have to rethink things - when I get back to where my VDSL2 spec is, and have time to peruse.

You have one suggestion from RobertoS to continue monitoring. An extra one would be to use a TBB ping meter, and see if it shows any packet loss - and if that changes when heavy downloading is going on.
Standard User Alexir
(learned) Fri 19-Apr-13 22:16:57
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Re: DLM and the NTE Modem


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
I think it is possible that TalkTalk were doing the slowing down, not the Openreach DLM


I did consider that because TT openly admit they slow down P2P traffic, but they say they only do so at certain peak hours times and only when the P2P traffic is passing - and my slow down was constant with a firm ceiling of 24meg which felt like a DLM cap.

The P2P traffic was probably just a coincidence but as my speed came back I thought I'd mention it just in case someone else experiences similar in future.
Standard User Alexir
(regular) Sun 02-Jun-13 08:12:02
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Re: DLM and the NTE Modem


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
I might have to rethink things - when I get back to where my VDSL2 spec is, and have time to peruse.


After six weeks of stable 38meg we decided to test again with another torrent and downloaded around 30gig over a couple of days, leaving it running overnight but stopping during the day. Almost immediately our speed has been reduced to 23.6meg. Basically this looks like a 24meg ceiling has been set by DLM and my guess is I will have to wait again for a few weeks before it resets back to 38meg.

So, any idea what's going on? Is the torrent download causing the speed reduction, the two events always seem to correlate even though the theory says they shouldn't. Is the 24meg ceiling set by BT DLM - TalkTalk tell me it is nothing they are doing, though their CS staff will only be following a script. TT used to traffic manage P2P but even that stopped last month to become 'totally unlimited' even for Essentials, the package I'm on.
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