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Author Topic: Very high noise margin drop in afternoon  (Read 64060 times)

roseway

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Re: Very high noise margin drop in afternoon
« Reply #30 on: January 13, 2008, 07:02:34 AM »

Apparently it does. More information Here. But it's a rather old router and may not have up-to-date performance.
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setecio

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Re: Very high noise margin drop in afternoon
« Reply #31 on: January 13, 2008, 10:22:16 AM »

Apparently it does. More information Here. But it's a rather old router and may not have up-to-date performance.


If you use the Thompson chooser for a home 1 user modem, it still comes up as a current product
http://www.thomson-broadband.co.uk/products/Details.asp?ProductID=532

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roseway

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Re: Very high noise margin drop in afternoon
« Reply #32 on: January 13, 2008, 11:02:49 AM »

So it does, you're right. The 510 series has been around a long time, but the v6 is still current if you only want a single user, non-wireless solution.

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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #33 on: January 14, 2008, 05:32:58 PM »

I think my lift and shift has actually made a small improvement.  The new DSLAM port seems to be relatively gentle, starting sync was 4320 day 1, at 6dB and IP profile 3000, post 3 pm  noise started to increase as per usual and had three downward resync's, but very small  3968,3776,3680.  Left it on overnight, as per Roseways suggestion, and the 3680 held which is good as my noise issue doesn't usually improve until around 7.30am.  IP profile held at 3000.  Prior to the lift and shift  on a good day I would have an IP profile of 1500, but I used to get savage cuts on resync, usual sync was 2300 and this would resync to 900-1000 with IP profile usually going down to 750-500K or even 250K (for 3 days) if there was another resync.  I assume this was because my target margin was 15dB, so clawing back from -4dB (when my connection drops) forces big drops in sync speed.  If that is right it is a big disadvantage with high target SNR margins, if they do get breached you will get hammered. 

Day 2 had one small resync upwards to 3744, followed by a resync down to 3712 in the post 3pm period. Then back to reality, sudden drop, resync at 2464, so much for the gentle DSLAM, IP profile dropped to 2000, still it's better than what I used to get.  Turned the router off at night.

Day 3 seems to be following pattern of Day 1 - starting sync 3968, followed by two small adjustments to 3776 and 3744 during the noisy period, IP profile still at 2000.

As my interleaving was switched off by the lift and shift I am seeing CRC errors, which I don't know how to interpret.  The router seems to cumulate errors until a resync, then starts again.  I have no idea at what level CRC errors should become a concern - how many a minute.  Can anyone help me on this.  I've asked for interleaving to be turned back on but that will take a few days.
 
Overall it is an improvement, the instability post 3 pm it is still there but the effects are not quite as severe.  Whether it remains this way only time will tell. Overall  I'm surprised by the very small reduction in sync after a drop (generally drops occur below -4dB).  Have attached router stats for day 1&2 - the red blobs are disconnects

Bought one of the £11 Speedtouch 510v6 off Ebay, will give that a go when it arrives.  Hopefully it will not join the pile of modems, routers, card readers, CPU's, memory cards, and general antique and next to worthless electronica which fill one cupboard.  If it doesn't work I'll try for an Engineer who has some specialist understanding of the process - not holding my breath though.


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kitz

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Re: Very high noise margin drop in afternoon
« Reply #34 on: January 15, 2008, 01:07:28 AM »

>> I have no idea at what level CRC errors should become a concern - how many a minute.

TBH I'm sure sure - there seems to be no hard and fast rule that Im aware of.
But the fact that youre running in minus SNR figures means that youre likely racking them up pretty quick.  This will have the impact that your throughput speeds during this period will be much slowed down.

>> Overall  I'm surprised by the very small reduction in sync after a drop (generally drops occur below -4dB).

I noticed that too when looking at the graphs which made me think perhaps there was one quick sharp burst which took the connection down... but then again being in -ve figures youre sailing close to the wind anyhow.

Looking at those graphs side by side shows a very obvious daily pattern.  It strikes me that the time it starts is about the time the kids will get home from school.  I know you say youre not particularly near your neighbours, but there are recorded cases where a faulty electrical item has knocked out adsl for a large portion of the street.

Something Ive also discussed with Azzaka with the ar7 chipset issue is the fact that the netgear is very good at holding on sync which helps a lot of lines..  however there may be some when the netgear should just say "ok enough" and drop the connection...  but instead it continues to hold on and rack up errors that perhaps it cant cope with.

This is possibly going to sound really stupid because I cant think of a technical explanation to do this, and it probably wont come to anything.. but next time the router gets down to -ve SNR rather than waiting for it to drop sync. Just try switching the router off completely from the power source and give it a total fresh start so it doesnt have a pile of errors stored.

ps can you tell Im now clutching at straws?
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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #35 on: January 15, 2008, 04:14:57 PM »

"I noticed that too when looking at the graphs which made me think perhaps there was one quick sharp burst which took the connection down... "

This was my feeling too.  I sample at every 90sec on routerstats and many of the small sync adjustments don't show as a disconnect, which I think means that the resync is occuring within the 90 sec interval.  Attached a trace of the whole of yesterday. Same pattern small sync adjustments.  Perversely the resync at around 2.00am resulted in a higher sync rate, which to my way of thinking kind of supports the sharp burst idea.  You can see that the line is noisy throughout the night until around 7 am ( this is typical behaviour) when it settles down until 3.30pm ish.  Basically I have a good line from 7am to 3 pm, outside of this period it is very noisy.  My IP profile has fallen to from 2000 to 1000 despite sync being maintained above 3000 during this period.  I wish I understood the DLM logic - its seems to be driven by the
number of resyncs.  What makes my problem so irritating is its impact on IP profile, I can live with the odd disconnect - most of the time I don't even notice them.

Sorry posted wrong graph

Speedtouch 510v6 just arrived gonna give it a go - let you know what happens

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« Last Edit: January 15, 2008, 04:17:14 PM by MikeS »
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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #36 on: January 15, 2008, 04:16:28 PM »

Sorry posted wrong graph

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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #37 on: January 15, 2008, 09:50:20 PM »

Well don't quite know what to say, the Speedtouch 510v6 ex Ebay arrived today and I connected it up about 1.30pm.  Very easy to set up even for me.  Turned on Routerstats and it sync'd at 4700, didn't trust that, looked very high so rebooted it sync'd at 4928 and 6dB.  Weather has been dire water pouring out of BT manholes and our drains so a good day to check it out.  Totally different from any previous router. All the other three (all AR7 chips) showed spikey noise margin movements plus a big drop off at around 3 pm (see graph from earlier post) .  So far the Speedtouch has shown only a slight decline  (2dB ish)  during the problem period post 3 pm. but none of the spikey ups and downs, all this when it is syncing at least 1000 higher. (attached routerstats trace).  The only caveat I have at the moment about the comparison is that yesterday I had interleaving turned off after the lift and shift. It was scheduled to be turned on today but I can't see anything on the modem stats that tell me if it's on or not.  I have to say when I had interleaving turned on in the past it made no difference to the spikey nature or the big drop in noise margin.  This may be a bit premature but I am cautiously optimistic.  b4dger had the same experience albeit with different Speedtouch model (sorry for being sceptical).  If this behaviour continues it does place a question mark against my AR7 router and its performance on my line, or to be balanced the DSLAM response to my AR7.  Maybe something Kitz can talk to Azzaka about. Will keep you posted when I have more data. 

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kitz

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Re: Very high noise margin drop in afternoon
« Reply #38 on: January 16, 2008, 01:11:18 AM »

Thanks for posting those - it certainly does look a lot better.

>> Maybe something Kitz can talk to Azzaka about.

We've discussed a few things. Azzaka is more knowledgable about the situation than me though.
One of the reasons why I suggested turning the router off last night is (as I said it may not make sense), but just a theory that the Netgear isnt handling errors too well and should be dropping the line instead of keeping hold.  I wondered if the rack up of errors was perhaps making things more unstable and a total switch off of the router may clear it for a while.
Like I said above though - clutching at straws, trying to find a solution.

>> Will keep you posted when I have more data.

Please do. :)
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b4dger

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Re: Very high noise margin drop in afternoon
« Reply #39 on: January 16, 2008, 11:25:14 AM »

>>b4dger had the same experience

Glad things are looking better for you  ;D
I was worried I was starting to look like a 'spammer' by recommending you switch to a Thomson router so many times  :-[

I read and read and read about peoples low SNR experiences and went through a few routers along the way.
My router is the 585v6 running 6.2.29.2 firmware - this firmware isn't tweakable using the DMT s/w but many have reported it to be the most stable for them, I'd go along with that...

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« Last Edit: January 16, 2008, 11:37:19 AM by b4dger »
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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #40 on: January 16, 2008, 06:03:36 PM »

Attached a trace of the first full day with the Speedtouch 510v6 and a comparison with a day from the SAR 600EH.  They are totally different in style.  Both show a fall in noise margin from 3pm ish to 7am ish but the Speedtouch looks controlled and slowly drops 2-3dB whereas the SAR is all over the place, with drops of up to 10dB.  Both are from after my lift/shift.  Other differences, are that the sync speed is about 1000 higher with the Speedtouch and the line attenuation 52dB SAR, 54dB Speedtouch.

I started the Speedtouch up today during the noisy period (5pm) and sync was still high at 4680.

I am now talking about that which I know very little.  My impression is that once the line enters the noisy stage, communication between the SAR and the DSLAM seems to get Ďout of wackí  in some fashion, maybe one of them is playing catch up, I donít know.  Then end result is large swings in noise margin which eventually result in a resync.  The very small changes on resync may support this.  They seem to be deciding that things were not as bad as they thought and relatively trivial sync adjustments are made (bearing in mind Iím dropping from -4dB), and on the last trace the resync was actually upwards. Because Iím sampling every 90 secs  I donít know whether the noise spikes are actually much sharper than appear on the graph, if this is the case it could also account for the modest changes on resync, as the line would be back in a Ďstableí state.  Sorry if this sounds like a load of rubbish I just donít have the technical knowledge to put it more coherently. 

Azzaka raised an interesting point in another thread.  If the instability on noisy lines is due to code issues between the router and DSLAM whose responsibility is it.   Whose responsibility is it to check that communication protocols between router and DSLAM are compatible.  Good question


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b4dger

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Re: Very high noise margin drop in afternoon
« Reply #41 on: January 16, 2008, 06:34:22 PM »

>>MikeS didn't say: "Thanks b4dger..."

No problem MikeS glad things are looking good!
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Ian1261

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Re: Very high noise margin drop in afternoon
« Reply #42 on: January 16, 2008, 07:12:56 PM »

Really sorry to interject this thread, it seemed a little more along the lines of my problem than I may have originally thought.

"You may have read my post about "Dropped connections, Resyncs, Flourescent lights, BT problem, Bit random - sorry"

@ b4dger... as you seemed to have had a similar problem with resyncs, (and the rest of you most helpful people).

Finally got an engineer out ( I asked if he could come after 5 when the line seems to be noisier, arrived at 3!) He checked line with his test router and got a no fault and very little crc error result! Suggested I keep on at BT if I am not happy!? Trouble is with his messing around with the connection of his router (which synced at one point at 2100!!?) and checking the crimps at the junction post, the lovely 'system' has interpreted that as a fault and I am at an even slower speed now (even though MY router has resynced for the second time since he left, 1st at 3616 and then again at about 5.30 at 3360), my actual speed is 1.7mb! I guess that should recover in a couple of days?

More to the point is maybe I can stop the resyncs with this Thompson 585 router you have tried successfully with. Are you still problem free? (sorry don't wish to tempt fate!) I have Netgear DG834Gv2 which I thought was well renowned for hanging in where all others failed? Just want something to hang on to my connection so I can boost my profile that elusive one notch! :) How easy is it to set up? What about wireless and port forwarding? Updating firmware etc. Any other ideas? I have read your 'story' - very interesting.

I also note MikeS has used the 510 with success.

Yours and anyone elses voluntary time consuming comments are VERY much appreciated.

All the Best

Ian
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MikeS

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Re: Very high noise margin drop in afternoon
« Reply #43 on: January 16, 2008, 08:25:25 PM »

Unfortunately routers/modems seems to be a lot like frogs, you have to kiss a lot before you find your prince or princess.  I have tried 4 or so and they all showed the same characteristics ( they were all, although it didn't mean anything at the time AR7 chipset routers).  They were new selling Speedtouch 510's for £11 delivered on Ebay so after 5 engineer visits I thought I was worth a punt.  So far it seems to have worked for me, doesn't mean it will for you.   You do however have my sympathy.  I tried for engineer visits late in the afternoon but I think they have 2 hour slots for each visit, so 3 pm is likely to be their last visit.
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b4dger

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Re: Very high noise margin drop in afternoon
« Reply #44 on: January 17, 2008, 10:46:21 AM »

Hi Ian1261,

Interestingly 2Wire are the only manufactures (that I've found) that actually make a reference to noise, and as in your case 'fluorescent lighting'.

From the 2Wire guide:
"High performance integrated modem. 2Wireís technology improves DSL1 performance, especially for
homes further away from the local exchange. It also minimizes common interference found when other
devices (such as dimmer switches or fluorescent lighting) are in contact with the DSL line."


When I used a 2Wire monitoring the SNRM showed that during the day it was completely rock solid! But during the evening it still dropped more than the Thomson - hence my switch. But from what I've seen the 2Wire manages 'noise' in an impressive way so may help you with your lights.

My ADSL is important to me, so buying both a 2Wire (£16 delivered from Digidave) and a 585v6 (£30 delivered from eBay) to evaluate was well worth it. My Netgear DG834v2 was causing much pain with dropped connections and the knock on affects on my IP Profile!

I can't answer your 'Port Fowarding' questions etc. as I don't use that. What I can tell you is that the GUI on the Thomson is rubbish but you can do everything through CLI/Telnet. The reverse is true with the 2Wire, the GUI is excellent but there is no Telnet facility.

Good Luck!
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