Yet another speed question...

[#1]

HI,
Just when I thought I was getting good speeds it all goes pear-shaped – grrrrrrrrrrrr!!! 
Couple of days ago my downstream connection was hovering around 5568 kbps, my IP profile was 4500 kbps and my throughput was over 4000 kbps and I was a happy chappie… Then suddenly everything collapsed around me.  Checked my downstream sync speed a couple of mornings ago and it had dropped a full 1000 kpbs, needless to say my profile had also dropped to 4000 kbps.  I did a manual reboot and got the sync speed back up again and was resigned to waiting ‘days’ before my profile came back up again.  Like I’m sure lots of others I find it annoying that the profile should follow the received sync speed so quickly when the sync speeds drop yet take ages to climb back up.
This morning checking my downstream sync speed (is this becoming an obsession I ask myself…) I find it’s dropped back ‘again’ – and sure enough my profile is now down to 3500 kbps.
Apparently the sync speed is dropping back during the night.  My downstream snr margin drops by a couple of dBs then but previously my D-Link has been quite happy working at an snr margin of 3dB so I assume I’ve had a couple of nights when it fell pretty low.
Couple of questions for the knowledgeable – whilst the router will sync to a lower speed – will it ever sync to a ‘higher’ speed or will it stay forever at the lower speed – until manually rebooted.  In other words if I'd left it at the lower speed would it stay there forever or untill I reboot?
Also is there any mileage in turning the router off at night, it would then never see the lower snr margins and would be rebooted in the morning when the figures are back up, so maintaining my higher IP profile.  If I were to turn it off is there any correct way of doing so?
My present stats are:-
Downstream sync  5472
Upstream sync  448
IP Profile  3500
Actual throughput  3236
Snr margin  5.2
(the snr drops to ~3 at night)
Previously  sync was  5568
IP Profile  4500
and throughput  4147
I’d welcome your thoughts, incidentally I’m sure someone will say that even a 5db snr margin is very low but my D-Link works happily down to about 3db.  Presumably the last couple of nights it’s fallen below what it normally drops to.  We’ve had a fair bit of rain, wonder if that has any bearing?  I may leave my RouterStats running tonight and see what I get.
John

[#2]

The only way to change the routers synch rate is to initiate a resynch
switching the router off overnight will get round the problem but I would see if you can monitor the noise margin overnight using something like routerstats which will give an indication of what is happening.
If you can I would connect the router and phone to the socket behind the master socket and see if it improves.
To switch off the router just disconnect the power supply if it doesn't have an on/off switch - you could leave it on and just disconnect from the telephone line if this is easier

[#3]

SNR does naturally drop in the evenings and overnight so this isn't hugely surprising.  However, if you run Routerstats it may highlight a specific incident that causes a sudden drop in SNR which initiates your resync event.
As I understand it, a resync event is the only thing that will change your sync speed (until 21CN, anyway).  A resync is forced by your SNR becoming unsustainable and causing a drop of the connection.  Unfortunately, no such resync is initiated if your SNR goes the other way.  Truly rate-adaptive logic is part of the ADSL2+ WBC product which should be able to alter sync speeds dynamically without a resync event, but ofc this is still some way off.
Turning your router off overnight will certainly mask the problem, although I would certainly attempt at least one overnight Routerstats log to see if it is just deterioration of SNR.
The correct way to turn a router off is to disconnect your DSL link from the control panel (if possible) , then power off the router.
B.

[#4]

Oldjim,
> The only way to change the routers synch rate is to initiate a resynch <
OK, that would obviously happen when the router was turned on again in the morning...
> see if you can monitor the noise margin overnight using something like routerstats which will give an indication of what's happening <

I did try a few evenings ago to see if I could tie in any fluctuations in the snr margin with something happening in the house - CH boiler going on/off etc but couldn't see anything obvious.
> If you can I would connect the router and phone to the socket behind the master socket and see if it improves. <
I have an ADSLNation filtered master socket faceplate and from some tests I've done before I couldn't detect any difference in stats either side of the faceplate - but I will certainly try that again.  I'm obviously not using external dangly filters.
> To switch off the router just disconnect the power supply if it doesn't have an on/off switch - you could leave it on and just disconnect from the telephone line if this is easier <
I asked that as I have read somewhere that merely puling the plug is not a 'good thing' - can't remember the reasoning behind it...  My D-Link has an on/off button so I can use that, and presumably leave it plugged into the faceplate ADSL socket.
Barry Z - thanks also for your input - came in just as I was going to hit the big red button!
I'll try and log some stats tonight and take it from there.
John

[#5]

Quote from: Barry

The correct way to turn a router off is to disconnect your DSL link from the control panel (if possible) , then power off the router.

This is more important than many people realise.  The 'dying-gasp' sent by the router is essentially telling the BT exchange that it is a deliberate shut down not a catastrophic loss of signal due to a line fault.  Pulling the telephone line a few times in a row will most likely land you with a higher SNRM and a lower sync rate and consequently a lower IP profile.

[#6]

Is ripping the power supply out of the back of the router a better way of powering down the router?

[#7]

Quote from: MickKi

This is more important than many people realise.  The 'dying-gasp' sent by the router is essentially telling the BT exchange that it is a deliberate shut down not a catastrophic loss of signal due to a line fault.  Pulling the telephone line a few times in a row will most likely land you with a higher SNRM and a lower sync rate and consequently a lower IP profile.

As I found out when we had 5 power cuts in 15 minutes 

[#8]

Well I left RouterStats running for the last 24 hours, thinking it might give me some idea when the router was re-syncing, I could then try and figure out if it was something at this end that might be causing it.  Needless to say it didn’t re-sync…
I’m pretty new at this, so not too sure what to expect, but I understand the line becomes more noisy at night and as the snr margin drops that’s when a re-sync might be most likely.
I’ve run RouterStats before and know that my snr margin drops from between 5 and 6 where it sits at most of the day to between 2 and 3 about 9pm, only coming back up about 6am the following morning.  Last night it dropped down to ~1.5 around 2.30am but the router did not re-sync.
Think I may have to accept that an IP profile of 4500 is pie in the sky – though I had it for a while - and that maybe 4000 might be more reasonable – if I’m lucky.  On the other hand I could coax it back up – then turn the router off overnight - maybe if it continues going up and down that’s what I might try.
MickKi you say that the:-
> correct way to turn a router off is to disconnect your DSL link from the control panel (if possible) , then power off the router <
Can I get away with just powering down via the on/off switch at the rear of the D-Link?  I think I could just about get the rest of the household to understand this!!!  Pulling plugs just might be pushing it…
Thanks to everyone who gave some input, this is a very steep learning curve for me.  I’m used to wireless broadband – no telephone lines – no routers/modems etc.  Worked great for years then my isp introduced a log-in facility using very poorly written software.  It would go for weeks asking for a password every 60 seconds – eventually did my head in – hence my appearance in the PN fold!
Regards,
John

[#9]

Hi,
Well, since posting the last mail, my downstream connection speed has dropped from 5472 to 3968, and my IP profile has dropped to 3000.  My snr margin has risen from around 5 to 11.1.
It all appears to be going down hill 
Would I be right in assuming that only PN/BT can manually alter the snr margin - it won't return to it's normal ~5db?
Maybe I’m becoming paranoid about these things…
John

[#10]

Yes.
The chances of your noise margin resetting itself are virtually zero.
You should really be aiming for a value of 6dB (which occasionally drops to 5+).
On a bad or long line you might have to settle for 9dB (which occasionally drops to 7 or 8dB).
Ask (reasonably persistently) for it to be reset to 9dB.
Follow all the checking procedures first though, in case the fault is self-generated.
Your noise shouldn't increase by a huge factor at night - is this associated with some external influence?
Such as street lights coming on?

[#11]

The 'dying gasp' packets are sent by a modem/router when you click on disconnect in its admin control panel.  Some send a packet upon power off, others don't.  No idea what Linksys does.
Simple advice:
Depending on the time of day and state of weather (damp) you resync at, you will find that you can get a higher or lower speed.  With experience you will find a sync speed at which you manage to retain your connection during the night.  100kbps up or down can make the difference.  Also with experience you'll find the time of day that you can fairly reliably get such a sync speed (perhaps you start a bit earlier at a lower sync and then resync every hour until you reach the sync speed you want).  Once you get it hold on to it.  Leave the router on all the time.
Repeated low speed resyncs will result in a higher SNRM at the exchange, so your 6db target SNRM was increased to 12dB to stabilise the line connection - that's how the DSLMax algorithms work at the BT exchange equipment.  If you get a high resync event and you manage to hold onto it for a considerable amount of time then the SNRM 'should' be lowered again by the BT exchange and your IP profile consequently increase.  However, the lowering of the SNRM may not happen on its own and you may have to request for it to be reset to a target level of 6dB.  No point doing this of course until the cause of the low resyncs has been found and repaired!
Gradual degradation of a connection could well be a DSL filter which is on its way out.  Have you tried replacing your filters?

[#12]

Quote from: axisofevil

Yes. The chances of your noise margin resetting itself are virtually zero.

I was afraid of that, that's why I was hoping that once I'd got a high re-sync and a good IP profile I'd turn off the router at nights - when it's most likely to lose sync - in the event I didn't quite make it!!!

Quote from: axisofevil

Yes. The chances of your noise margin resetting itself are virtually zero. You should really be aiming for a value of 6dB (which occasionally drops to 5+). On a bad or long line you might have to settle for 9dB (which occasionally drops to 7 or 8dB). Ask (reasonably persistently) for it to be reset to 9dB. Follow all the checking procedures first though, in case the fault is self-generated. Your noise shouldn't increase by a huge factor at night - is this associated with some external influence? Such as street lights coming on?

My snr sat at 'tween 6 and 7 all day dropping 2 or 3 dbs overnight and that's when it would very ocasionally re-sync.  Not too sure 'what' happened a couple of days ago but it re-synced during the day which I find rather odd.  I wasn't monitoring the sync at the time but normally it would have been around the 6 - 7 mark and I know this D-Link SAL-2640B will stay in sync down to about 2 or 3 db - strange.
I've looked at any obvious excursions and tried to tie them down to something happening locally but no luck.  I have an ADSLNation filtered faceplate on my BT Master Socket and two phones, one main and one extension both fed thru' an Orchid dialler box which I have no reason to believe is causing any problems.

Quote from: MickKi

Repeated low speed resyncs will result in a higher SNRM at the exchange, so your 6db target SNRM was increased to 12dB to stabilise the line connection - that's how the DSLMax algorithms work at the BT exchange equipment.  If you get a high resync event and you manage to hold onto it for a considerable amount of time then the SNRM 'should' be lowered again by the BT exchange and your IP profile consequently increase.

I suppose that now my snr has increased getting a much higher sync than what I have at present is going to be difficult, I normally find mid morning gives me the best opportunity.  Think I'll try and run RouterStats and when I find the snr has gone up a bit I'll quickly try and re-sync and see if I can build it up a bit.
I really should be getting a life!!!!!!!!!
Thank you both for your interesting and helpful inputs,
John