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Author Topic: DLM and the effect of turning off the router at night  (Read 31290 times)

burakkucat

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Re: DLM and the effect of turning off the router at night
« Reply #15 on: June 18, 2011, 05:06:15 AM »

Until two years ago my brother in law's system (running Redmond 'doze XP) was making its broadband connection via a USB port to the ISP supplied "horseshoe crab" (as I called it). When the system was powered off the USB modem was, therefore, powered down. There was never any problem with his throughput speed. Eventually, as he wanted to have wireless capabilities, he contacted his ISP who then provided him with a more up-to-date modem/router/WAP connecting via the system's Ethernet port.

My copper pair is completely unbundled -- I am LLU, with TalkTalk as my ISP. I mention my ISP as it may have some relevance due to being different equipment from that of BT. From day one, I have always powered off my modem/router at the end of the day and switched it back on the next morning. At present, I am not using my 2Wire 2700HGV but my Netgear DG834Gv5. Here are the current statistics --

Quote
/ # adsl version
Version           : 1.12
DriverVersion     : 1.75
APIVersion        : GS_API_652
FirmwareVersion   : E.25.41.64   A
DspVersion        : 0x000000e1

/ # adsl opmode
Current trained adsl mode    : G.Dmt

/ # adsl channel
Current trained adsl path    : Interleaved
Downstream Bit Rate          : 4192000 bps
Upstream Bit Rate            : 896000 bps

/ # adsl margin
Downstream Noise Margin      : 9.0 dB
Downstream Attenuation       : 51.0 dB
Downstream Power             : 18.9 dBm
Upstream Noise Margin        : 9 dB
Upstream Attenuation         : 29.0 dB
Upstream Power               : 12.4 dBm

/ # adsl perf
============= NEAR END ===========
FEC   : 10
CRC   : 0
HEC   : 0
============= FAR END ============
FEC   : 0
CRC   : 0
HEC   : 0

/ # adsl defects
============== NEAR END =============
ES  (Count of errored seconds): 0
SES (Count of Severely errored seconds): 0
LOS (Count of Loss of signal): 0
============== FAR END ==============
ES  (Count of errored seconds): 0
SES (Count of Severely errored seconds): 0
LOS (Count of Loss of signal): 0

Note that although I am connected to 21CN equipment that is ADSL2+ capable, my service is "Up to 8 Mbps" i.e. is capped at 8 Mbps. As a result of that cap and due to the fact that I still have not rationalised my internal wiring :-[ I have set the DG834G to use G.Dmt.

I would appreciate an analysis of the statistics by one of the appropriate experts (you know who you are ::) ) . . . please pretend that I am a novice and know nothing.

Perhaps, once I have rationalised my internal wiring, I should do the required experiment -- contact my ISP and request that my download SNRM be set to 6 dB and then leave my modem/router constantly powered up?
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waltergmw

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Re: DLM and the effect of turning off the router at night
« Reply #16 on: June 18, 2011, 11:02:32 AM »

@ Eric,

Perhaps it would also help if DLM functions were considered in the context of both 20CN and 21CN systems, whether on ADSL or ADSL2?
I have observed the results of the DLM logic on our long lines that most 21CN ADSL lines do not resynchronise nearly as often as 20CN ones.
Also that the IP profile change responds very rapidly and the speed steps are different and I think more of them are defined.
With the new double entry BT speed tests, IP profiles are recorded for both up stream and downstream values.
The sync speed often increases a little and the noise margin decreases.

How much these observations are just down to Huawei / Infineon compatible chip sets and how much might be due to different DLM logic is quite unclear to me.

(  I have also noted that TalkTalk + O2 LLU and Orange + possibly some BT services have been configured for ADSL2 on long lines where in theory they should remain on ADSL.)

Kind regards,
Walter
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razpag

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Re: DLM and the effect of turning off the router at night
« Reply #17 on: June 18, 2011, 11:46:00 AM »

@ Eric,

Perhaps it would also help if DLM functions were considered in the context of both 20CN and 21CN systems, whether on ADSL or ADSL2?
I have observed the results of the DLM logic on our long lines that most 21CN ADSL lines do not resynchronise nearly as often as 20CN ones.
Also that the IP profile change responds very rapidly and the speed steps are different and I think more of them are defined.
With the new double entry BT speed tests, IP profiles are recorded for both up stream and downstream values.
The sync speed often increases a little and the noise margin decreases.

How much these observations are just down to Huawei / Infineon compatible chip sets and how much might be due to different DLM logic is quite unclear to me.

(  I have also noted that TalkTalk + O2 LLU and Orange + possibly some BT services have been configured for ADSL2 on long lines where in theory they should remain on ADSL.)

Kind regards,
Walter

That again flies in the face of what I see on a daily basis, and with my own circuit as well. My 'uptime' when on 20CN was measured in many months, my 'uptime' on 21CN is measured in very few days. 21CN is far more unstable with it trying to transmit data at the higher end of the 2.2Meg frequencies imo.
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HPsauce

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Re: DLM and the effect of turning off the router at night
« Reply #18 on: June 18, 2011, 12:17:09 PM »

@razpaq - Do you think that instability is ADSL2+ vs ADSL1, or something specific to your circuit/locality or a "feature" of the BT implementation of ADSL2+?

Obviously if it is generally less stable on ADSL2+ (and colloquially I'd say that agrees with what I hear, on all ISP's) then how DLM works and whether it is different on ADSL2+ is significant.

I'm in the fortunate position of "Being" on an LLU non-DLM ADSL2+ connection, which has been running at 19444kbps (interleaved) with a nominal 3dB target noise margin since the last router reboot - 402 hours ago (over 2 weeks). (I can't run non-interleaved for any length of time due to variable interference from an unknown source)
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razpag

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Re: DLM and the effect of turning off the router at night
« Reply #19 on: June 18, 2011, 12:57:11 PM »

Sorry HP, i've read your post a couple of times and am not 100% sure what you are asking mate ?

All I know and can comment on, is what I see on a day-to-day basis. Add to that my own personal experience of my home circuit, and I can honestly say that 21CN is far, far more unstable than 20CN. I personally put it down to the high ammount of 'errors' on 21CN circuits (due to the extremely high frequencies utilised), which in turn makes the DLM go into overdrive.

As I say, this is IMHO. Walter has obviously got his own findings from his own customers. 
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HPsauce

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Re: DLM and the effect of turning off the router at night
« Reply #20 on: June 18, 2011, 01:06:04 PM »

am not 100% sure what you are asking mate
Sorry, sometimes I ramble....
Anyway your answer is clear enough, thanks.

My own experience (which includes many of my clients) is that ADSL2+ is indeed inherently less stable and that DLM can be quite brutal in dealing with that.
(though on my own exchange the only ADSL2+ is LLU so my immediate area isn't "afflicted" so much)
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roseway

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Re: DLM and the effect of turning off the router at night
« Reply #21 on: June 18, 2011, 03:41:19 PM »

@burakkucat: The stats you posted above look quite reasonable for your 51 dB attenuation, but it looks as though your target noise margin may have been raised to 9dB by DLM at some point. We could only be sure of this by seeing what your noise margin is immediately after a router reboot.
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  Eric

burakkucat

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Re: DLM and the effect of turning off the router at night
« Reply #22 on: June 18, 2011, 04:49:55 PM »

Quote
We could only be sure of this by seeing what your noise margin is immediately after a router reboot.

That is easily obtained --

Quote
/ # adsl margin
Downstream Noise Margin      : 8.5 dB
Downstream Attenuation       : 51.0 dB
Downstream Power             : 19.2 dBm
Upstream Noise Margin        : 10 dB
Upstream Attenuation         : 29.0 dB
Upstream Power               : 12.4 dBm

/ #
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roseway

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Re: DLM and the effect of turning off the router at night
« Reply #23 on: June 18, 2011, 06:25:06 PM »

So your target noise margin has almost certainly been raised to 9 dB.
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  Eric

HPsauce

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Re: DLM and the effect of turning off the router at night
« Reply #24 on: June 18, 2011, 07:42:37 PM »

Now I've just seen something interesting in the PlusNet forums.
A customer was complaining about slow speeds. PN staff confirmed he was ADSL1 and no ADSL2+ was available through them.
They then said:
"Looking at your recent speedtest, your IP profile has dropped down from 7150kbps to 500kbps. Our connection logs are also showing that your router is powered off during the night. Can you confirm to us if you are turning the router off?. If you are, can you ensure you keep your router switched on so your IP profile will raise back up to 7150kbps"

Now, reading that CAREFULLY they're not actually saying that turning it off caused the problem, but are saying recovery will be helped by leaving it on 24*7.  :graduate:
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roseway

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Re: DLM and the effect of turning off the router at night
« Reply #25 on: June 18, 2011, 07:58:43 PM »

That would indeed make some sense.
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  Eric

jeffbb

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Re: DLM and the effect of turning off the router at night
« Reply #26 on: June 18, 2011, 11:41:32 PM »

Hi

I am going to have to read up again on the way the DLM updates the profile  (Target snr and interleave ). 2 things I remember is that ar ecord is kept for errors and or Resynchs in 96 15 minute blocks over for every 24 hrs , and this data is assessed every 24 hrs .Then the DLM actions profile changes as appropriate . BUT there are other factors as well. All this is related to Target snr and interleave

Nowhere have I seen anything that actually has any bearing on the IP profile ,this is a direct result of a bad synch and it is known that there is  a variable recovery time depending on the % difference. Obviously many bad synchs would result in the Target SNR and or interleave depth to be increased .

Now whether switching off router overnight slows any recovery of the IP profile  I am not sure . Even during initial training period  you are nor required to leave router on 24/7 . All connections of 15 minutes or more  are valid for assessing the line. 

Regards Jeff
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waltergmw

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Re: DLM and the effect of turning off the router at night
« Reply #27 on: June 19, 2011, 12:18:22 AM »

Gentlefolk,

Sorry I have been away. I expect the reason I observe the good 21CN stability is that we try to insist that all long line services remains on ADSL (1) G.DMT which I think should not allow the higher frequencies to be used.

I suspect that many are not heeding the advice from e.g. here:-

http://support.zen.co.uk/kb/KnowledgebaseArticle.aspx?ArticleID=11125

My experience suggests that it's well worth being transferred to 21CN even on long lines PROVIDED you stay on ADSL 1. We still have pretty awful speeds but the stability does seem to help prevent wider throughput speed fluctuations we experienced on 20CN ccts. In any case I understand that eventually there will be no option but to be transferred.

Hence my original queries about how DLM works differently on a 21CN line.

Here's my best example where you will see the service was transferred on 15 March 2011 with the line card changing from TI to Infineon.

Kind regards,
Walter



[attachment deleted by admin]
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razpag

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Re: DLM and the effect of turning off the router at night
« Reply #28 on: June 19, 2011, 07:41:03 AM »

Now I've just seen something interesting in the PlusNet forums.
A customer was complaining about slow speeds. PN staff confirmed he was ADSL1 and no ADSL2+ was available through them.
They then said:
"Looking at your recent speedtest, your IP profile has dropped down from 7150kbps to 500kbps. Our connection logs are also showing that your router is powered off during the night. Can you confirm to us if you are turning the router off?. If you are, can you ensure you keep your router switched on so your IP profile will raise back up to 7150kbps"

Now, reading that CAREFULLY they're not actually saying that turning it off caused the problem, but are saying recovery will be helped by leaving it on 24*7.  :graduate:

Thanks for the 'post up' HP. Reading that CAREFULLY heavily suggests, that turning your router off every evening is detrimental to the circuit.  ;D
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roseway

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Re: DLM and the effect of turning off the router at night
« Reply #29 on: June 19, 2011, 07:50:17 AM »

Thanks for the 'post up' HP. Reading that CAREFULLY heavily suggests, that turning your router off every evening is detrimental to the circuit.  ;D

Only detrimental in that, in the opinion of the writer, switching off the router at night may delay the recovery of the IP profile after it was depressed by a low speed re-sync.
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  Eric
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