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Line stats query -FourFourDevon (split from routers? which is best?)

Community Veteran
Posts: 1,101
Registered: ‎10-09-2010

Line stats query -FourFourDevon (split from routers? which is best?)

Sorry to hijack this thread, but is there somewhere that explains what SNR numbers mean?  Indeed explains what the output of the adsl ctl is?
Quote
adslctl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 8000
Channel: FAST, Upstream rate = 443 Kbps, Downstream rate = 23493 Kbps
Link Power State: L0
Mode: ADSL2+
Channel: Fast
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 2.8 20.9
Attn(dB): 10.5 7.0
Pwr(dBm): 0.0 10.3
Max(Kbps): 26160 860
Rate (Kbps): 23493 443

me thinks my SNR is low, but I have no real idea what that means...
adie:green split from router thread and topic changed. ]
7 REPLIES
mapletree
Grafter
Posts: 644
Registered: ‎28-07-2007

Re: routers? which is best?

Kitz has some good articles on ADSL technology.  http://www.kitz.co.uk/adsl/linestats.htm has lots of stuff about attenuation and SNR.
Community Veteran
Posts: 1,617
Thanks: 22
Registered: ‎29-06-2010

Re: routers? which is best?

Quote from: fourfourdevon

Down Up
SNR (dB): 2.8 20.9
Attn(dB): 10.5 7.0
Pwr(dBm): 0.0 10.3
Max(Kbps): 26160 860
Rate (Kbps): 23493 443

me thinks my SNR is low, but I have no real idea what that means...

Yes, your downstream SNR is low - it should be at least 6dB. Second, yours is the highest downstream synch I think I have ever seen, just about as much as a very short line on ADSL2+ is capable of. Third, your upstream is capped for no good reason, although PlusNet do this automatically. I should raise a ticket to get your upstream uncapped, and get your downstream margin reset to 6dB. You should be getting at least twice your upstream speed, and your downstream speed is so good it is unlikely to affect it. It may even improve it, as greater upstream bandwidth cuts down on the restriction of ack packets being sent.
Community Veteran
Posts: 1,101
Registered: ‎10-09-2010

Re: routers? which is best?

OK cool, will raise a ticket and see what happens.
I am less than 100 meters from the exchange, as the bird flies I would say about 50 meters, although I guess the line will twist and turn at least a bit.
What effect will having the downstream SNR set to 6Db have?  I do have disconnect problems, on average about 1.5 times a day.  I can go 2 sometimes 3 days without a disconnect, but then other days I will disconnect 2 or 3 times.
Moderator
Moderator
Posts: 18,807
Thanks: 1,991
Fixes: 256
Registered: ‎11-01-2008

Re: routers? which is best?

Quote from: Jaggies
Yes, your downstream SNR is low - it should be at least 6dB. Second, yours is the highest downstream synch I think I have ever seen, just about as much as a very short line on ADSL2+ is capable of. Third, your upstream is capped for no good reason, although PlusNet do this automatically. I should raise a ticket to get your upstream uncapped, and get your downstream margin reset to 6dB. You should be getting at least twice your upstream speed, and your downstream speed is so good it is unlikely to affect it. It may even improve it, as greater upstream bandwidth cuts down on the restriction of ack packets being sent.

That's not correct, the lowest is 3db, i have mine pinned to this as part of the old DLM trial - uncap your upload by all means but i wouldn't recommend kicking off your retraining as you might not get your 3db target back!

Customer / Moderator / If it helped click the thumb / If it fixed it click 'This fixed my problem'

Community Veteran
Posts: 1,617
Thanks: 22
Registered: ‎29-06-2010

Re: Line stats query -FourFourDevon (split from routers? which is best?)

As FFD says, his connection drops every so often - it would probably be better if the target noise margin was reset to 6dB. My own line is much more stable at 6dB. When I had it at 3dB it would drop down to around 0dB on occasion, and would invariably result in a dropped connection.
stallan
Grafter
Posts: 282
Registered: ‎02-11-2007

Re: Line stats query -FourFourDevon (split from routers? which is best?)

Mine is also 'pinned' at 3db. It would be worthwhile you recording the line drops (Routerstats maybe). If it is during the evening/night then the SNR could be at 0.5 or thereabouts and therefore the reason for the drop.
reboot the router between 10ish and 2ish to get optimum SNR and take it from there.
If you get the SNR reset to 6db, then there are always tweaks to reduce it. 
jojopillo
Grafter
Posts: 9,786
Registered: ‎16-06-2010

Re: Line stats query -FourFourDevon (split from routers? which is best?)

Hi fourfourdevon,
I could get this hard fixed to 6dB downstream which may well help with any drops.
Jojo Smiley