topic Re: SNR Reset process - how does it work? in Broadband

SNR Reset process - how does it work?

tonycollinet — Tue, 21 Jan 2014 12:51:31 GMT

I'm told I've had my SNR Reset.
I thought that it would go instantly to the 3db level, and then stability would be checked from there. I reply to ticket suggests that I shouldn't expect any change to the SNR until the end of the training period.
Is that correct?

Re: SNR Reset process - how does it work?

jelv — Tue, 21 Jan 2014 12:58:38 GMT

Usually a SNR reset will go to the default target noise margin of 6db.
Could you post the router stats please.

Re: SNR Reset process - how does it work?

tonycollinet — Tue, 21 Jan 2014 13:09:32 GMT

Router stats from yesterday (out of my ticket) shown below.
For further info - I connected in October, and since then (until one or two weeks ago) had a 3db target SNR with a solid 19+M connection. Then for no explicable reason it rose to 9db. (Some background info in this thread: http://community.plus.net/forum/index.php/topic,122181.0.html )
In that thread, Chris confirmed my line was stable and reset the SNR - nothing happend. I requested via ticket for it to be done again (Completed Sunday), again, no change. Second repsone to ticket (based on the unchanged router stats below) is that I have to wait until 23rd Jan to see the result.

Stats:
Modulation : ADSL2+
Annex Mode : Annex A/L
Line State : up
Lan Tx : 679
Lan Rx : 668
ADSL Tx : 575
ADSL Rx : 474
CRC Down : 0
CRC Up : 0
FEC Down : 0
FEC Up : 0
HEC Down : 0
HEC Up : 0
SNR Up : 6.3
SNR Down : 9.7
Line Attenuation Up : 9.6
Line Attenuation Down : 14.0
Data Rate Up : 1050
Data Rate Down : 15349

Re: SNR Reset process - how does it work?

jelv — Tue, 21 Jan 2014 13:16:39 GMT

Has there been a resync that you haven't initiated?

Re: SNR Reset process - how does it work?

tonycollinet — Tue, 21 Jan 2014 13:19:30 GMT

There was a resync around the time of the reset on Sunday - no SNR change, so I did another as the ticket requested a few hours later. Still no change.

Re: SNR Reset process - how does it work?

goldenfibre — Tue, 21 Jan 2014 13:36:35 GMT

15349k on the line attenuation of 14.0 with snr of 6, I get 15759k on the line attenuation of 31.0 with snr of 6 before (now current 18359k with snr of 3) as your line attenuation is very short than mine, you should get higher sync rate (maybe you had more than one bt socket in the house or ring bell on the bt socket) ?

Re: SNR Reset process - how does it work?

tonycollinet — Tue, 21 Jan 2014 17:53:26 GMT

No, I've had months of 3db no problems with plusnet, and before that years with BE.
The inexpliable change of profile has co-incided with congestion at the exchange (The thread linked above was started to discuss that, then after a week my SNR profile went south). However, I can't emagine why exchange congetsion would impact sync speed/profile.
There has been no known change to my internal configuraition.

Re: SNR Reset process - how does it work?

tonycollinet — Thu, 23 Jan 2014 23:02:52 GMT

OK - as I thought.
This post from Chris suggests I should have seen an instant change in sync speed after the SNR reset.
http://community.plus.net/forum/index.php/topic,122448.msg1064457.html#msg1064457
The SNR and sync speed have not even twitched - it has now been 10 days since the first attempt, and there has not been the slightest improvement in speed.
I was asked in the ticket to wait until 23rd January - it is now 23rd.
PLEASE can someone look at this, and try to get me a proper SNR reset, that actually does something.

See ticket 79985892

Re: SNR Reset process - how does it work?

gary42 — Fri, 24 Jan 2014 09:24:34 GMT

As goldenadsl says, there shouldn't be a need to drop to a 3db margin. You should be syncing around 22Mbps with that attenuation. Although that extra 3 should push you to the magical 24
I'd also expect your upstream to be up over 1200Kbps.
Maybe try connecting in the test socket to rule out any internal problems?
Having said that it is possible to have your target margin set to 3db without going through the full re training process.
I've had both types of reset done on my line in the past.
One took around a week to drop back down to 3db and the other happened immediately.
I think it depends on what type of reset is requested by the support guys.
Gary

Re: SNR Reset process - how does it work?

tonycollinet — Fri, 24 Jan 2014 16:55:01 GMT

To be honest, I don't mind what is done to sort things out - only that they are SORTED without waiting another 10 days while nothing happens.
2 weeks ago I had a 3db profile and a 19MB/s+ connection. Then it dropped to 9db and 13-15mb/s for no apparent reason. (No frequent line drops)
PLEASE PLEASE can someone set it back the way it was.

Re: SNR Reset process - how does it work?

tonycollinet — Fri, 24 Jan 2014 22:12:35 GMT

Well, just for fun, I've just tried connecting to the test socket.
Tiny change to the attenuation, absolutely zilch on the connection speed or SNR.
Modulation : ADSL2+
Annex Mode : Annex A/L
Line State : up
Lan Tx : 1274
Lan Rx : 1143
ADSL Tx : 999
ADSL Rx : 874
CRC Down : 0
CRC Up : 0
FEC Down : 0
FEC Up : 0
HEC Down : 0
HEC Up : 0
SNR Up : 6.7
SNR Down : 9.7
Line Attenuation Up : 9.5
Line Attenuation Down : 13.0
Data Rate Up : 1050
Data Rate Down : 15349

Re: SNR Reset process - how does it work?

jelv — Fri, 24 Jan 2014 22:48:08 GMT

Keep an eye the the error rates as well - it may be the speeds are similar to begin with but if there are fewer errors you could safely go to a 6db target SNR which would give more speed.

Re: SNR Reset process - how does it work?

tonycollinet — Fri, 24 Jan 2014 23:17:15 GMT

I know I can safely go to 3db target SNR, because it's been sat at that for about 3-4 years - as long as I've had ADSL2+
Except for the last two weeks of course.

Re: SNR Reset process - how does it work?

jelv — Sat, 25 Jan 2014 00:17:32 GMT

Can you confirm that you have checked that nobody near the route between you, the cabinet and the exchange has started using any different electrical equipment?

Re: SNR Reset process - how does it work?

tonycollinet — Sat, 25 Jan 2014 00:24:19 GMT

No, but isn't it the case that in order to trigger the DSLAM to increase target SNR, it needs to see line drops, ie lack of stability - not just interference?

This has not happened.

Re: SNR Reset process - how does it work?

jelv — Sat, 25 Jan 2014 00:28:17 GMT

I believe high error rates can also trigger an increment in the target SNR - but yes drops are more usual.

Re: SNR Reset process - how does it work?

goldenfibre — Sat, 25 Jan 2014 00:31:43 GMT

I had that problem a year ago when Plusnet reset 3dB as the DLM kept put my line up to 9dB and logged a fault team. The fault supplier spoken to bt on echat and managed to turn off DLM and fixed snr 3dB. I had disconnected the router many times over the last 6 months and DLM haven't rise my snr. It's all stay at 3dB for the last 10 months now. Even I did mess around with new BT Openreach modem, BT Home Hub 5 and Netgear DGND3700v2 and the DLM haven't kicked SNR rise ever since. It stayed at 3dB.Thanks to BT for magic work around at the exchange.

Re: SNR Reset process - how does it work?

Townman — Sat, 25 Jan 2014 09:54:43 GMT

With an attenuation of 14dB at a SNRM of 6dB you should see a synch speed around 22Mbps.
The fact that you are way off this points to a line problem somewhere. Have you done a quiet line test? 17070 option 2
Have PN done a line test (is your phone service with PN)?
If there is a line fault, SNRM resets will deliver nothing - as noted elsewhere, keep an eye on error rates... Indeed install RouterStats and get some constant monitoring reports 24x7 to see if there is a marked drift of SNRM / error rates.

Re: SNR Reset process - how does it work?

tonycollinet — Sat, 25 Jan 2014 09:59:09 GMT

The main problem here is that the SNR Reset did nothing. In order to do a training, it HAS to try the lower target SNR's otherwise, it cannot check stability. The only excuse would be if the line was unstable or with high error rates at 9db. It isn't
During the whole process of TWO attempts to reset SNR, the level DID NOT CHANGE - not even immediately after the reset, which is what would be expected.