ADSL 2+ LLU Connection Problems !

Hi all, hope you don't mind helping me !

I have been posting over at vivaciti (My Provider) but haven't had much response yet.

My posts from there.

Before I start, speeds, throughput, latency etc are all great. I've been on LLU for 2 Months now with Vivaciti.

So the problems, about 4 weeks into the service the SNR margin started dropping to below 3dB at which point the internet stops working although it doesn't actually disconnect. This usually happened 2-5 times a week but recently it's gotten more frequent usually 1-2 times every 2 days.

To up the SNR I usually either reboot the router or re-connect using the DMT Tool at which point it rises to 9dB or 5-6dB with DMT after which the connection is fine until the next time it happens.

Now strangely this doesn't usually happen overnight it happens at random intervals during the day so I'm not sure what is causing it.

I haven't raised a ticket on this yet as I'm unsure what the cause is, I will get round to running the line from the test socket and see what happens. At the moment I'm using a High Quality RJ11 Cable and ADSL Nation Filtered Face Plate. The router I'm using is the D-Link DSL2640B, I've been using DMT to Sync at around 22000+ Kb.

My line stats :-

Connection Type : ADSL2+
ADSL Status (Downstream/Upstream) : 21170(Kbps) / 1023(Kbps)
Connection Up Time : 0 hour, 51 min, 32 sec


Mode: ADSL2+
Line Coding: Trellis On
Status: No Defect

Downstream Upstream
Rate (Kbps): 21170 1023

SNR Margin (dB): 5.9 6.7
Attenuation (dB): 17.5 8.0
Output Power (dBm): 12.7 16.5


Super Frames: 193623 193621
Super Frame Errors: 70 7165
RS Words: 33303182 0
RS Correctable Errors: 1864355 0
RS Uncorrectable Errors: 841 N/A

HEC Errors: 54 40331
OCD Errors: 0 0
LCD Errors: 0 0
Total Cells: 156179368 2623512608
Data Cells: 1336138 46954514
Bit Errors: 0 126564

Total ES: 4772 584
Total SES: 2688 241
Total UAS: 93 351

Speedtest

http://www.speedtest.net/result/499913217.png

DMT Snapshot.

http://img10.imageshack.us/img10/7796/dmt.th.jpg

I've lost internet 3 times now today, whats strange though is the SNR has remained at 5.8-6.0dB through the loss of connection which is stange, I've been stable at 3.0dB before.

All that seems to be happening is the internet connection drops and the amount of errors increase by a fair margin until re-synced

While I'm here how much would interleaving affect Sync Speed, Throughput and Latency ?

Cheers,

gamehungry

Posts continued :-

What would you say the most likely cause of all this is ?. Considering we had ADSL Max 8Mb for 2 Years at this address without a single problem. (Minus a Junction Box issue which was fixed). LLU was fine for 4-6 Weeks then this started, everything is still the same bar the Filtered Faceplate and high quality RJ11 which were installed when we went live on LLU.

SNR Monitor Results, Look normal ?

http://img35.imageshack.us/img35/7796/dmt.th.jpg

Right, internet went offline again at around 9PM !. Same as usual SNR dropped although only to 6.3 at which it should be stable. Router stated connection was still live as always but I could not connect to the interent. All I get is error after error (Line Errors).

This time I took some stats while it was offline, hopefully you can spot something.

Screens.

http://img3.imageshack.us/img3/429/screen1jyr.jpg

http://img3.imageshack.us/img3/6693/screen2tvz.jpg

Router stats.

Connection Type : ADSL2+
ADSL Status (Downstream/Upstream) : 19969(Kbps) / 1023(Kbps)
Connection Up Time : 11 hour, 58 min, 9 sec

Mode: ADSL2+

Line Coding: Trellis On
Status: No defect

Downstream Upstream
Rate (Kbps): 19969 1023

SNR Margin (dB): 6.2 6.5
Attenuation (dB): 18.0 8.0
Output Power (dBm) 12.6 19.0


Super Frames: 2675284 2537941
Super Frame Errors: 20710 528
RS Words: 433396166 0
RS Correctable Errors: 612607 0
RS Uncorrectable Errors: 2650144 N/A

HEC Errors: 1225 45422
OCD Errors: 1 0
LCD Errors: 3 0
Total Cells: 2017276510 2891895011
Data Cells: 7533324 51177788
Bit Errors: 0 143822

Total ES: 472 674
Total SES: 334 306
Total UAS: 22 480

Destination Gateway Subnet Mask Flags Metric Service
89.145.254.70 0.0.0.0 255.255.255.255 UH 0 wizard_pvc
192.168.1.0 0.0.0.0 255.255.255.0 U 0
0.0.0.0 89.145.254.7 0.0.0.0 UG 0 wizard_pvc

Router Log.

Jun 23 21:00:41 syslog emerg BCM96345 started: BusyBox v1.00 (2008.07.02-12:36+0000)
Jun 23 21:00:41 user crit kernel: eth0 Link UP.
Jun 23 21:00:41 user crit kernel: ADSL G.994 training
Jun 23 21:00:41 user crit kernel: ADSL G.992 started
Jun 23 21:00:41 user crit kernel: ADSL G.992 channel analysis
Jun 23 21:00:41 user crit kernel: ADSL G.992 message exchange
Jun 23 21:00:41 user crit kernel: ADSL link up, interleaved, us=1023, ds=19969

I've now removed the filtered faceplate from the Master Socket and am connected to the Test Socket, see how that goes !

Final Post :-

Well moving to the Test Socket did nothing !. Lost connection again over night and again this morning although the SNR was normal 8.8dB (This Morning). I'm gonna have to find another router to try now.

------

Sorry any of that is confusing !. Any suggestions ?

You need to find out when the line returns to normal. 9 PM is the time when street lights could be coming on, but they go off about 5AM at the moment.

Some form of external influence causing the line to become unstable, like a dodgy street light or a neighbours tv. More noticeable at the higher speeds from what I've seen.

My line was rock sold at 8meg on vanilla ADSL since I moved to an ADSL 2+ service, nearly 2 years ago, although I get max speeds it goes through bursts of not being stable, always returns to top speed. Friends who have similar fast setups have experienced similar issues.

Thanks for posting guys, all help is appreciated.

Considering it's totally random at the minute I guess interference is most likely, it has happened throughout the day sometimes once or twice in quick succession.

So I can assume it's the line rather then modem etc ?. Would different modems cope with the session of disrupt better and automatically re-sync ?.

As the modem reports been unable to Ping the DNS server (As Shown In A Screen, Linked) etc is that down to the errors ?.

Cheers,

gamehungry

Have you tried forcing the modulation to adsl2 instead of adsl2+, I know you'll have less speed, but do it on a temporary basis to see if this increases stability?

Adsl2+ operates at twice the frequency to that of adsl and adsl2, therefore is susceptible to greater interference in certain instances, give it a go anyway?

Could be the router hardware not being 100% compatible with the DSLAM. It's always worth either borrowing or having a look on ebay for something to try on the line. There are plenty of Sky badged routers available which can be reflashed to stock firmware.

The fact that the router is unable to ping the ISP DNS server is nothing to worry about as it might be set to not respond to pings.

Thanks for the help guys. How would I go about forcing ADSL 2 ?. Instructions would be great.

With regards to the router I have a BT Homehub knocking about I could unlock and flash with the Thomson 7G firmware, I just need to find a suitable power supply for it as I lost the orignal, I tried one 9v one but it would'nt work properly (Too much power ?). Is that worth a go.

My current router is using the Broadcom BCM6348 chipset, is that not one of the best ?.

My connection works great when it's not unstable btw, I get a nice 17+Mb throughput inc Overheads. Whats the max achievable ?

Thanks again guys !.

gamehungry

Edited by deleted (Wed 24-Jun-09 18:50:17)

To tweak the SNR and get a little bit more out of your line you would need to have a compatible router, I think the Broadcom chipset is better than the AR7, well from my experiences anyway.

To see the routers you could use DMT with see here for version 7 and here for version 8 - different version work with different routers, personally I think you'd probably be best going for a Netgear DG834GT(get an old sky one off ebay for about £25-30) you could then flash that with DGteam firmware here then all you need to do is go to the advanced settings and adjust the SNR by a percentage in there. Generally your target snr should be 6db, but depending on how stable your line is this could be increased in increments of 3, so 9, 12 or 15db, I have seen my dads up to 18db, after some showers and the line went really flaky.

You can read up about that on the kitz website with how snr affects connection speeds etc.

I suppose it depends whether you've got the money to spend, I have found the BT homehubs and business hubs ok, when on bt network, but when on LLU your better of tweaking it that little bit more, when you haven't got profiles to worry about.