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Author Topic: Thomson TG585v7 -- CLI configuration of SN Margin?  (Read 40247 times)

Azzaka

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #15 on: April 10, 2008, 04:58:41 PM »

They can set the limit on DSL, with 2 priviso's:

1) DSL IPStream - Can limit it, depending on the problem.
2) DSL Max - Can be limited by the ISP only if they are on LLU. If the customer is then the ISP can set a profile to limit the speed depending upon the connection and most will lower it according to the errors on the line.

I hope this helps.

Leo
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b4dger

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #16 on: April 10, 2008, 08:00:22 PM »

Hmmm, sort of...

I think for this discussion we can forget about LLU as a lot of the issues are with IP Profiles ping-ponging around etc  :(

"DSL IPStream - Can limit it, depending on the problem"

So can an ISP limit someone's connection to 4672kbps for example, if that helps the customer maintain a more stable connection ?

Thanks...
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Azzaka

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #17 on: April 11, 2008, 12:30:31 PM »

Fixed rate can be limited. If i am not wrong. BT can limit the line speed but only by changing the snr value and or limiting the profile to a fixed rate service.
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b4dger

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #18 on: April 11, 2008, 12:37:39 PM »

Hmmm...

It's a max line I was interested in.
Don't worry if it's not something you deal with.
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rwm32

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #19 on: April 11, 2008, 01:18:31 PM »

Thanks for that, Azzaka.  Shame that BT only set the SN target in 3dB steps...

Anyway, here's an update on my line, which I was leaving alone at 7680kbps...

  • Ran overnight at 7680, SN margin range 6.5 to 5.5dB
  • Mid-morning yesterday: re-sync'd from peer to 8000 when the SN margin went up to7.5dB
  • Mid-evening yesterday: re-sync'd to 7680 when the SN margin dropped to 5dB
  • 5.00 this morning: re-sync'd from peer to 7808 for no obvious reason (SN margin range 5.5 to 6dB for previous several hours)
  • mid-morning today: re-sync'd from peer to 8000 for no obvious reason (SN margin range 6 to 6.5dB)

Interpretation of this: I don't have a clue what's going on; just wish I could combine the line stability of the TG585v7 with the DG834v3's tenacity at holding sync with very low SN margins.

Having watched this passively, I have just used ftp to upload a config file (user.ini) with this line in the [ adslpots.ini ] section:
[ adslpots.ini ]
config modemoption=30000000200000000600000000000000

then, having confirmed that the new file was in fact on the modem, I went into the CLI and did
:config load flush = enabled filename = user.ini

Long, long wait. Reboot. Same old story: sync at 8000kbps with 8.5dB SN margin, and :adsl debug modemoptioninfo shows the unmodded settings.  So I'm laying this one to rest; life is too short.

However, the huge bursts of 100,000's of FEC errors have not happened since I put a clip-on ferrite toroid on the DC power line into the modem yesterday - though I'm not assuming cause + effect just yet.

All the same... since it was the high error rate that was the original concern, if the ferrite does turn out to have got the errors down to an acceptable level, does it matter if the line re-syncs quietly from time to time?  As there's no way the line will hold an IP profile of 7000 but doesn't look like syncing down (to coin a phrase) below the 6500 threshold, the answer is: probably not, unless this will upset the secure VPN to which we're being migrated in a few weeks' time.

Yet another long post -- sorry. But I think that's the end of the saga, at least until the VPN arrives...

Thanks, folks.
rwm32
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Azzaka

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #20 on: April 14, 2008, 01:30:11 PM »

Hmmm...

It's a max line I was interested in.
Don't worry if it's not something you deal with.

BT can cap the line if its DSL MAx, however, if they do then it can cause a lot more issues than not. If you have an SNR of 15db and the line still drops then check for an intermittent fault. I spoke with a colleague to get a second opinion and he agrees that you have an intermittent fault on your line, and this will be worth checking.
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Azzaka

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #21 on: April 14, 2008, 02:06:33 PM »

rwm32,

The only way that your line looks like it will be stable is if the SNR is manually set, or if you have the intermittent fault sorted. The line itself is stable for 2 weeks approx. on an SNR of 9, the moment the SNR is reset to 6 it drops again. The only way to set the SNR manually is if the line becomes very intermittent, and then BTW will set the SNR value accordingly.
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rwm32

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #22 on: April 14, 2008, 02:38:05 PM »

Interesting you should say that, Azzaka. How we all love that phrase 'intermittent fault'!

However -- and this definitely falls into the 'famous last words' category -- the line's been OK for the last approx 24 hours at 7680kbps. No unforced resyncs; FEC count running at under 1500/hour; CRC at under 20/hr; SN margin 6dB +/- 0.5dB.  What's more, the huge bursts of 100,000's/minute in the FEC count have not happened since I put the ferrite toroid on the modem's DC line.

So I'm hoping for the best.  As a precaution I thought I'd keep an eye out for a v6 546 or 585 Speedtouch on e-bay -- one which I can put a DMT-compatible firmware on.  Then if needs be I could try nudging up the SN target without getting it stuck at a too-high level by BTw.

Thanks, anyway.

rwm32


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b4dger

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #23 on: April 14, 2008, 04:56:59 PM »

If you have an SNR of 15db and the line still drops then check for an intermittent fault. I spoke with a colleague to get a second opinion and he agrees that you have an intermittent fault on your line, and this will be worth checking.

Hi Azzaka,
You've quoted me but I think your reply may have got mixed up with someone elses???
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b4dger

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #24 on: April 14, 2008, 05:01:34 PM »

...What's more, the huge bursts of 100,000's/minute in the FEC count have not happened since I put the ferrite toroid on the modem's DC line...

Hi rwm32,
Just for interest where did you get your "ferrite toroid" from, was it one of the ones stocked by Maplin?
In the past I had read about these with conflicting views. As you put yours on at the same time as the change of router - if possible could you try removing it to see if the bursts of noise return? I guess that's the only way to see if this was the actual cure - don't worry if you don't want to remove it for a test.
Thanks.
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rwm32

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #25 on: April 14, 2008, 05:57:17 PM »

Yup, it was from Maplin.

In fact, I changed the router several days before putting the ferrite toroid thingy on, so it's at least semi-correlated -- though I agree that the proof would lie in removing it.  Unfortunately, having investigated, I genuinely can't now tell which side is the clip and which is the hinge and am (perhaps unsurprisingly) reluctant to risk using force to find out.  I've put it on a loop of the DC lead (i.e the lead goes through it twice), close to the mains adaptor end.

If my earlier posts are confusing about when the modem got swapped, it's because I had the TG585v7 up & running for a while before the Netgear DG834 .37 firmware was released. I swapped back to the DG834 for a brief trial after flashing it with the new firmware.

Hmm. Dates: I think the TG585 first went on-line in the evening of 28th March.  The shielded modem lead and ADSLNation filter came on Sat 5th April, and I spent a happy time re-routing and re-positioning everything that afternoon.  The ferrite thingy arrived on 10th April, having been ordered when it became apparent that the weekend's efforts, though very worthwhile in terms of improving reported SN margin and stability, had not got rid of the 100k bursts of FEC count.

I stopped 24hr monitoring on Sat 12th, though continuing during the day. The biggest FEC burst I've recorded since 10th was just over 30k in 5 mins, and the overnight (unmonitored) count hasn't exceeded 100k; the base FEC rate seems to be 500-1500 per hour.

Hope that gives you more of an idea about it all and makes up a little for not getting the definitive 'removal' test.

cheers
rwm32
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rwm32

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #26 on: April 16, 2008, 09:42:37 PM »


Update 1 --- ferrite toroid:


... I genuinely can't now tell which side is the clip and which is the hinge and am (perhaps unsurprisingly) reluctant to risk using force to find out.


:'(  I obviously need new specs. Son took one look and pointed out which the catch side is.

So I did a brief test: within an hour of removal, one mega-burst of 90k in under a minute in the FEC count. With the ferrite on, as I mentioned, the biggest burst was around 30k over a number of minutes. So I'm convinced: the ferrite went back on.

Update 2 --- SN Margin / DMT Tool:

Well, in fact, I put the ferrite thingy on a different DC line. Having had more unsolicited re-sync'ing (up in the morning + down in the evening), I gave in and bought an ST546v6 on e-bay, which arrived today.  (Chose that model for the 6.1.4.6 firmware, which although it has the 300s repeat delay on querying the stats built in nevertheless allows DMT Tool tweaking and spectrum SN margin analysis. No WLAN, of course.)

To cut a long story short, upping the SN margin to 8.5dB prevents the modem re-sync'ing up during the day, when RF interference round here is confined to two bands, and keeps the CRC error rate down to around 2/hr in the evening, when RFI tends to make the bottom fall out of a much wider frequency spectrum.  Oh, and it lets me sync at 7456, which is just enough to hang on to a 6500kbps bRAS profile.  ;D

So sadly the TG585v7 is now back in its box and on the spares shelf, alongside the DG834v3... and the Voyager 210...

And that, I feel, is probably the end of the story.

rwm32
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b4dger

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #27 on: April 17, 2008, 08:59:45 AM »

Thanks for the updates.

Is this the clip on Ferrite you are using?
http://www.maplin.co.uk/Module.aspx?ModuleNo=32799&criteria=ferrite&doy=17m4

And am I right in thinking you used it between the transformer and router?

Glad to hear your Speedtouch 546 is working well for you with a gentle SNR tweak - just goes to show that BT's 'system' doesn't work well for everyone. It's a shame your new v7 can't be tweaked. For the record you could still use a 585v6 with DMT if you put the right f/w on it.

Don't worry you're not the only one with a cupboard full of routers...  :D
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rwm32

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #28 on: April 17, 2008, 09:42:44 AM »

Yes, that's the right page at Maplin. The one I got is code N89AB (and you do only get one, not the four which the picture suggests).  I've put mine on the thin DC lead between the transformer and the router; with care, it's possible to fit two thicknesses of the DC lead into the clip, which prevents it sliding around and is said by some to improve its effectiveness.

546 still looking good this a.m. (famous last words...)
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kitz

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Re: Thomson TG585v7 -- CLI configuration of SN Margin?
« Reply #29 on: April 21, 2008, 12:39:36 PM »

I seem to recall reading something late last year where BTw were thinking of abolishing the fixed rate products. Though I cant remember where I read it so I may be dreaming?  They still have a lot of dslams that wont support MAX so it could be a while before they do.

I do recall though that some ISPs (eg BTr) dont like putting their customers on fixed rate products
1. the ISP gets charged for moving them over (about £5 + vat) yet to max is free
2. the actual port rental is dearer on a fixed rate product PM than it is for Max (somewhere around 65p per month)

Max itself has a few fixed rate profiles:-
  • Max Capped Rate Profile 500
  • Max Capped Rate Profile 1000
  • Max Capped Rate Profile 2000


If the line is a "cronic flapper" then the DLM can automatically put the line on one of the above profiles in order to increase stability. 
Quite often the (IPStream) ISP wont even know whats happened - theres a couple of cases on this forum where this sort of thing has occurred and its sometimes hard to distinguish between a "normal fixed" rate product and a Max capped product (Both will have the 288 upstream, arent rate adaptive and wont have IP profiling).

The ISP cant specifically order a Max Capped product as part of the product set, but iirc has to instead request via the fault process to put a line on Max capped in order to help stabilise a line for eg.
 
It can also be requested if say for eg the ISP is moving all their residential accounts over to MAX from fixed rate.. and a user is already on a fixed rate product... the ISP knows you are on a long line and can say only get a say a possible 512k sync.. in that circumstance the ISP can request a Max capped 500 to ensure that the line doesnt get clobbered with IPprofiling.

Aside from those profiles though - no theres nothing where an IPStream ISP say could limit a line sync speed to say 4Mb.

As regards using the router to do so - yes Ive seen it myself on one of the routers Ive used.  Unfortunately i cant remember which one - but at a guess most likely the SAR110 which has a Globespan chipset- therefore also looking at the likes of the Voyager 205 although dont quote me on that.
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