Continual dropouts

Hi all,

Over the last few weeks i have been getting a lot of dropouts on my connection, and sync speed has slowly dropped to under 6000Kbps. Speedtester is showing my profile as around 4500Kbps. I can't get the full print at the moment as it wont run the test properly. My throughput has been varying from 1000Kbps to 4200Kbps (figures approx).

Over last few nights I have replaced the line filter and have managed to icrease sync to 7200Kbps, but I was still gettting dropouts, so I have now relocated the router to connect at the test socket.

My stats other than the sync speed have not altered.

I have posted the stats below, any advice or feedback on them as I am really not sure how to decipher what they are telling me, despite 2 days of reading sites on this stuff. Any help very much appreciated.

Details from DG834GT via RouterStats

**DOWNSTREAM**

Noise Margin: 14.2 dB
Connection Rate: 7200 Kbps
Line Attenuation: 29.0 dB
Power: 19.8 dBm
Max Rate: 7744 Kbps

SF: 263139
SF Errors: 1
Reed Solomon: 17893482
RS Corrected: 1688
RS Un-Corrected: 7
HEC: 1
Errored Seconds: 3
Severe ES: 1
Interleave Depth: 32


**UPSTREAM**

Noise Margin: 22.0 dB
Connection Rate: 448 Kbps
Line Attenuation: 16.5 dB
Power: 12.1 dBm
Max Rate: 1124 Kbps

SF: 263676
SF Errors: 2
Reed Solomon: 2241246
RS Corrected: 12
RS Un-Corrected: 0
HEC: 2
Errored Seconds: 0
Severe ES: 0
Interleave Depth: 4


**Totals**

Total Up Times (From SF counts):
WAN: 0 day, 01:14:53
LAN: 0 day, 01:21:31

CRC: 438
LOS: 1
LOF: 9
ES : 3


Bytes Transferred (ppp0):
Tx: 1367832 (1.3 MiB)
Rx: 20012403 (19.0 MiB)

IP address: 86.141.210.8

I have also run a tracert to bbc.co.uk to check latency, results below:

Tracing route to bbc.co.uk [212.58.224.138]
over a maximum of 30 hops:

1 2 ms 2 ms <1 ms 192.168.0.1
2 35 ms 33 ms 34 ms esr13.edinburgh6.broadband.bt.net [217.47.157.14
4]
3 34 ms 33 ms 33 ms 217.47.157.13
4 36 ms 33 ms 34 ms 217.47.207.6
5 36 ms 33 ms 34 ms 217.41.174.9
6 35 ms 33 ms 33 ms 217.41.218.146
7 35 ms 33 ms 34 ms 217.41.218.50
8 35 ms 34 ms 34 ms 217.47.187.113
9 34 ms 33 ms 34 ms core1-pos12-1.edinburgh.ukcore.bt.net [217.32.16
9.209]
10 44 ms 42 ms 44 ms core1-pos14-0.birmingham.ukcore.bt.net [62.6.204
.133]
11 47 ms 45 ms 45 ms core1-pos0-1-0-0.ealing.ukcore.bt.net [62.6.204.
218]
12 48 ms 45 ms 47 ms core1-pos5-0-0.telehouse.ukcore.bt.net [194.74.6
5.122]
13 112 ms 303 ms 182 ms 194.74.65.42
14 180 ms 142 ms 141 ms 212.58.238.153
15 46 ms 49 ms 47 ms virtual-vip.thdo.bbc.co.uk [212.58.224.138]

Trace complete.

Again, thanks in advance!

With that attenuation you should be getting the full 8128kbps connection, with a profile of 7150.

However interleaving is on, so probably reducing that maximum to 7616kbps with a profile of 6.5Mbps.

By the look of it you are only getting 7200kbps because the drop-outs have caused your target noise margin to be raised.

By the test socket, I assume you mean the one on the wall at the back in this pic?

Try and see how things go from there if you can.

What router are you using?
Are you just using the short ADSL cable that comes with it, or also a phone extension cable?
Have you got a Sky box or a phone-connected burglar alarm?

I used to get 8128 many months ago and it dropped slightly, then this started.

The test socket is the one you refer to in your pic. The Router is connected to this directly with only its own lead via the microfilter. In the normal location the router is connected to an extension socket hardwired to the master socket, and not using an extension cord.

The router is a Netgear DG834GT.


Can I force it back up using the Set Target SNR in Router Stats?

Edited by st278 (Thu 16-Jul-09 23:43:30)

If you have the ring wire connected, (T3 in the pic), and possibly T4 (which has no use - just being kept tidy), gently disconnect them and tuck them out of the way. See this FAQ.

You should then get the same performance from the external master socket as from the test socket, but bear in mind the highest sync's are achieved by connecting betweem 8am and 4pm at this time of year. (In the winter 11am-2pm).

Is the extension pukka phone wiring, or builder-fitted rubbish? That can make a big difference.

I only use Router Stats Lite which doesn't have that facility. (Router Stats didn't work well with the SpeedTouches I had before I got Netgears). But it should work.

The three ways I have used with Netgear are DMT, though I don't like that for graphing, DGTeam firmware which is popular with Be/O2 users, and the CLI.

You need to reduce the target SNRM in order to increase the sync speed.

You are at a very unusual point though. The normal rule is that the lower the target margin the higher the sync. However when the line is good enough to exceed the maximum, the system automatically raises the SNRM from the maximum to soak up the spare - for stability.

So quite what will happen when you tweak the margin down I'm not sure. Just make sure you don't re-sync more than a few times in an hour, as doing so is what sends the target up in the first place.

I reckon you will almost certainly find you cannot get above 7616kbps. Dealing with that is for later.

Hi There, thanks for taking the time to assist me.

The extension is wired using pukka BT cable that an engineer accidentally left at the house, and is only utilising connections to pins 2 and 5.


Last night I reduced the SNR to 1db and the router is now sync'd at 8128Kbps

Current stats are:

ADSL Link................Downstream.........Upstream
Connection Speed....8128 kbps............448 kbps
Line Attenuation.......29.0 db...............16.5 db
Noise Margin...........11.3 db.................23.0 db

It's not just about reducing the target SNR and getting the sync speed up. At that kind of levels you're going to be looking at having dropped packets, slow speeds and generally unreliable broadband service. 6dB is generally considered quite low in itself, if your router cant distinguish the signal that being your traffic from random noise on the line you wont get much of a service.

OK I get that, but I have seen a dramtic increase in speed of even simple page loads since I did that.

Can you advise where I should go from here?


Do I leave it a few days, see if the IP profile recovers then let it re-sync normally?

In reply to a post by st278:

OK I get that, but I have seen a dramtic increase in speed of even simple page loads since I did that.

Can you advise where I should go from here?

Do I leave it a few days, see if the IP profile recovers then let it re-sync normally?

It sounds a bit as though the 7200kbps sync has brought your profile up to 6Mbps from something much lower, as that is what would cause a dramatic increase in page load speed.

I don't know what tweak you applied, I very much doubt if it was to 1dB as I find that sort of level is inly attainable through the CLI by setting the Q4 percentage to 1 or 2. Surely the lowest RS offers is 10%?

It doesn't matter though, as if you look at the stats you posted the system has responded by giving you the 8128 then raising the running margin considerably. Given that, and an attenuation of 29dB, I reckon everything is fine.

The profile will now take a few days to rise to 7150, as I said before. I gather you know how to check it with the BT Speed test.

Just in case your target margin has been set to 9dB, (the only way to know is from some router logs or by reading the stats immediately after connection), try to stay connected as you are now for 10-14 days. That usually causes the BRAS to drop it back to 6dB. It causes a re-sync when it does that, and if that is at night you may find a sync a bit below 8128 again. In which case a simple resync in the day should get 8128. Though the profile may have dropped a fraction for a few days as a result.

Success!

Latest readings from speedtester.bt.com

Test1 comprises of two tests

1. Best Effort Test: -provides background information.
Your DSL connection rate: 8128 kbps(DOWN-STREAM), 448 kbps(UP-STREAM)
IP profile for your line is - 7150 kbps
Actual IP throughput achieved during the test was - 6623 kbps

2. Assured Rate Test: -provides background information.
Assured Rate IP profile on your line is - 600 kbps
Actual IP throughput achieved during the test was - 518 kbps

Oh and signal forced to 1db for SNR is rock solid, no further disconnects.

Edited by st278 (Fri 17-Jul-09 21:10:32)

In reply to a post by st278:

Success!

Latest readings from speedtester.bt.com

Test1 comprises of two tests

1. Best Effort Test: -provides background information.
Your DSL connection rate: 8128 kbps(DOWN-STREAM), 448 kbps(UP-STREAM)
IP profile for your line is - 7150 kbps
Actual IP throughput achieved during the test was - 6623 kbps

2. Assured Rate Test: -provides background information.
Assured Rate IP profile on your line is - 600 kbps
Actual IP throughput achieved during the test was - 518 kbps

Oh and signal forced to 1db for SNR is rock solid, no further disconnects.

What you are calling SNR is actually SNRM - the two are very different. Unfortunately some modem/routers also call it SNR. Yours calls it Noise Margin = 11.3dB.

The connect-time setting is only relevant at that point in time, and immediately after the value can change. In this case exactly as I predicted.

Last night I reduced the SNR to 1db and the router is now sync'd at 8128Kbps

Current stats are:

ADSL Link................Downstream.........Upstream
Connection Speed....8128 kbps............448 kbps
Line Attenuation.......29.0 db...............16.5 db
Noise Margin...........11.3 db.................23.0 db

Anyway, your profile is back at 7150 and everything is hunky-dory . What the BRAS has set for "target" noise margin doesn't matter unless you get a night-time re-sync.

Edited by RobertoS (Fri 17-Jul-09 22:47:15)