High downstream SNR

[#1]

Hi @jab1,

I've seen this now and posted a further update.

[#2]

Had another resync at 1658 this afternoon to 12.448 Mbps, with a D/S noise margin of 4.8. (just for info)

---------"------------------ 1958 this evening to 9.006 Mbps      ----------"---------------------- 12.1 -------"--------

Edited to add further information.

[#3]

Right, just so I have a record, in case I forget to take a copy of ticket number  185013821, I was told in a phone call after the engineers report had been received that SNR target would be pinned @ 9dB (too high IMO), and it should stabilise.

I was told in the call to reboot the router in 4 hours, but as that would mean rebooting at the worst time for interference, I advised the PN rep that I would defer action until today. That was agreed, and I rebooted (and changed DSL cable for good measure), around 1445.

The result of that, is now that I am back at 13.5Mb/s connection speed and a D/S SNR of 3.1 again.

The engineer advised me all my equipment was fine - although he didn't like the TG582n - tough, as I do, so this leads me to think there is something wrong in the BT network, external to me.

EDIT: Exactly 50 minutes later, it re-synched at 9.95 speed and 10.9dB SNR - what the **** is going on?

Any chance this can be looked at, please?

[#4]

What firmware version is the 582n running?

[#5]

10.2.2.B - which is, I believe, the last.

[#6]

Right - ANOTHER DLM-induced reboot and I'm back to 13.2Mb/s connection speed and a D/S SNR of 3.1 as of 1830.

Someone or something is upsetting my connection, and the SNR pinning is not holding'

@MatthewWheeler, @Gandalf, @TheMightyAJ

[#7]

Hi @jab1 

I've tested your service today and can see that your router is indeed syncing at 9.9Mbps and your SNR on D/L is 10.6. 

This sync speed is over and above the 5.5-7.5Mbps Estimated Speed Range which our supplier has provided for your line - and DLM seems to be doing its job. Since the last drop on this graph; 

you have had a constant session without a drop in connection - this appears to match with the times you provided in your above post. 

I do understand that this seems to be happening rather regularly, but it appears that no matter what we are trying to do, the SNR rises and your sync speed slightly falls (however, it stays above the High End Estimate). 

Given that it is Sunday evening, I am unable to do much in regards to talking to our suppliers as nobody is there at the moment. I could perform another change to reduce you back to a SNR of 9 - but this would again require you to reboot the router in 4 hours time, which would be a horrible time on a Sunday night to be fiddling around with your router. 

I think the best think I can do at the moment is pass this to our early team and get somebody to pick this up, discuss it with our suppliers and inform you or the next step. 

Sorry I can't be of more help right this minute. 

Kind Regards,

MoR

[#8]

@MasterOfReality Cheers for that. I wouldn't attempt a reboot in the hours of darkness under any conditions, so your suggestion is welcome.

I will just mention that the very good OR guy that came out earlier this week said I shouldn't expect anything much above 8/8.5 Mb/s and I would be happy with that (and 6dB SNR), but we seem to be unable to get the system to agree to that.

[#9]

Read back over this thread again, think back how my problem was solved.

In my case the DLM also seemed to do strange things, and dropping me down to high SNR. It was caused by the DLM being set in "Super Stable" (see Kitz DLM) - and in my case my mean time between errors never went below red threshold).

Anyway its clear from @Gandalf post, you are on custom DLM settings, both you mean time between errors and resets, has been set to one day. This means your line never goes in the red, however it also doesn't say how the DLM chooses target margin - and that seems your problem.

So just wondering, rather than a custom DLM mode, would your link work better with one of the standard settings? Now as  you want 6dB of margin, I guess  you need "Stable" so red threshold of MTBE = 300, and green threshold MTBE = 6000. For me "Standard" settles on 3dB - and i expect the same for you; but that has a high rate of FEC ...

Minor niggle, on "Stable" the red limit for MTBR is 4 hours 40m  - so we would have to hope that your disconnects are caused by the DLM/DSLAM - and so aren't counted as "Reset" ...

Anyway just a though - maybe worth trying ...

[#10]

Certainly worth thinking about, @summers - thanks. As  @MasterOfReality said earlier, he is passing this to the day-time team, so I will wait for them to respond.

I am going away for three weeks in just over a week, so we'll see how things go in the next 8-9 days. When I return in January, I intend to substitute a new router (another TG582n), but I have enough to do before going away, and as it is still usable, I don't want to disturb the connection any more until I turn it off over those 3 weeks if I can avoid it.

I'm only swapping the router as it is the last bit of my own side which hasn't been changed, so if the problem returns/persists after I do the swap, I am fairly certain I can turn round and tell BT/OR to sort a problem in their equipment.

[#11]

I've placed an order to move you to the Stable config, which should complete by tomorrow.

Let me know how things go over the next few days.

[#12]

Cheers, Anoush.

I'll keep my eyes on it for the next week or so.and if stays stable, I'll hold off on swapping he router.

@Gandalf

[#13]

No problem, fingers crossed!

[#14]

@Gandalf I thought we'd cracked it, but minutes after I'd spoken to one your faults  (thanks for the quick response PN) and asked her to close the ticket, DLM threw another hissy-fit and decided to rack the SNR up to 14.8!! (the highest I've ever seen) and consequently rob me of about 1.5Mb/s of connection speed - I'm now down to 7.85.

I don't really want to  start the process again - I'm away for 3 weeks from next Wednesday - but it looks like  we are going to have to revisit this in the New Year.

[#15]

Sorry to hear this

If your SNR is changing like that to a very high level there'd be more of an underlying issue I think.

It may be worth us arranging another engineer visit for further investigation into this.