Line stability issues and line statistics advice

Hi all,
I've had BT Infinity (business option 2) for a few days and since day 2 it has gradually been getting worse. I was originally using the supplied Openreach modem and Business Hub 3, however due to the sudden lack of connection speed (dropping from 76Mbps~ download to about 0.3Mbps~ download, if that) and having to resync I thought it would be one of those causing it.

So I tried my Cisco 887VA directly in the data port and it produced the same symptoms as the OR modem and Business Hub 3, but this time I was able to notice that I had massive spikes of HEC and FEC errors (ranging from 10,000 to 40,000 per second). These spikes didn't occur most of the time, only suddenly, most of the time I was lucky to get about 1 error a second.

I've tried the following to eliminate possibilities that it's something internally here:
- Changed modem and router
- Changed RJ11 cable
- Changed LAN cables (rediculous but I did so anyway)
- Changed cordless phones to corded phone
- Moved all electrical wires or equipment (except the modem) away from the master socket
- Checked the wiring
- Tested 17070 #2 (Quiet Line Test) on the corded phone (no noise noticeable)

Since Saturday it has been raining off and on, and ironically since then it has managed to go worse each time it synced. Until this morning about 1am I was unable to keep a sync for more than one hour before the FEC/HEC errors spiked massively and not recover unless I disconnected and reconnected the RJ11 cable. This morning at roughly 5:30am interleaving depth was introduced by DLM, though I didn't see any HEC/FEC spikes cause that this time. Since then I've noticed only a small amount of FEC/HEC errors on the GUI and graphs, but a massive amount of RSCorr instead.

I'm not certain but I have a feeling the problem exists but the interleaving delay is now masking it. Could someone tell me if the below statistics appears to be normal? Interestingly FEC on the telnet connection shows a massive value compared to the web GUI value given.

Since Link time = 5 hours 26 min 33 sec
FEC: 74604360 401
CRC: 394 48
ES: 51 42
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0

I've obviously unlocked the OR modem so I can see this. Everytime I re-sync the noise disappears, for a while, then returns. I still think it exists looking at that FEC count on interleaving, but interleaving is managing to filter it out.

Log this with BT

Ok, how should I word this? Obviously I'm not meant to unlock the Openreach modem to find these horrid errors in the line stats. Do I just simply say everything I said except mentioning the error counts? E.g. I changed phones, tried another Openreach modem (borrowed from a friend), tried my router via the OR modem instead of the Hub, etc. etc?

Oh, and should I lock it before I call them?

Edited by Ixel (Wed 13-Jun-12 12:31:59)

Hi from J-in-Bristol.
I turned on this morning and have found very slow speeds - down from 2314 to 529 Kbps.
(Sorry but I do not know any of your tecnical terms)
I have since rebooted and have been able to get a web page up but it all just seems slow this morning.
I have BT broadband
I thought that I would get my two hapensworth in!
J-in_Bristol

Thanks for the reply but I'm using Infinity FTTC, not ADSL broadband.

Any suggestions from anyone about how I should word this to BT Business?

Another update to provide some graphs.

Line analysis: http://i.imgur.com/Mtr0Q.png
Sync and errors analysis: http://i.imgur.com/OCuFw.png

Based on those do you think I should phone support, and lock the firmware on the OR modem again before phoning?

In reply to a post by Ixel:

Another update to provide some graphs.

Line analysis: http://i.imgur.com/Mtr0Q.png
Sync and errors analysis: http://i.imgur.com/OCuFw.png

Based on those do you think I should phone support, and lock the firmware on the OR modem again before phoning?

How did you measure the "sudden lack of connection speed (dropping from 76Mbps~ download to about 0.3Mbps~ download, if that)", because those stats look pretty good.

They show that you are on an ECI DSLAM, syncing at 96Mbps, with throughput capped at 80/20Mbps. Many people would chew your arm off to have a connection like that.

The FEC count might seem huge, but it has to be viewed in relation to the number of data frames transmitted and received. And empty frames are sent even when there is no layer 3 traffic. And those empty frames are still checked for errors. So the error counters will keep on rising, even when there's no internet traffic to/from your PC.

Since you've had FTTC for only a couple of days, maybe give it a bit longer to level out. Hopefully it will turn out that you're one of the 'worried well'

cheers, a

Edited by asbokid (Wed 13-Jun-12 17:34:38)

Hi,
Thanks for the reply .

Before interleaving depth increased (which I hate as I'm a first person gamer too, but at the current level of interleaving I can tolerate it) I found when I had a sudden burst of FEC's and HEC's (10k - 30k in an extremely short period of time) it rendered the downstream almost unusable. Ironically the upstream and ping wasn't effected. In order to restore my connection I found disconnecting the RJ11 cable and reconnecting it made it work again, for a while anyway. Strangely the noise virtually disappeared when this was done, as you can see from the HEC/FEC error graphs for last night at 11pm and 1am. If I didn't intervene the modem didn't automatically lose sync and re-establish.

Now interleaving is enabled, the line appears stable, but I thought that it might also be masking a line problem, I suppose I'll only know this as and when DLM reduced the interleaving depth back to 1 (OFF).

My original attainable rate on Friday, Saturday, Sunday and part of Monday was around 103Mbps~, but since then has gone down a little (not a big problem though as I can see). I'll go along with this 10 day thing I keep hearing about, though from my understanding I thought the DLM constantly monitors the line anyway.

Finally, in regards to the FEC count, as I say, before interleaving depth was increased this morning about 5:30am I found the connection became unusable when I had a huge burst of them come in. As soon as I disconnect and reconnect the RJ11 cable it goes back to normal. Hmm, I'm confused . I found analysing ADSL errors was far easier.

I forgot to say that I'm more than happy with the connection when it's stable, but there are, or were (before interleaving depth increased) occurances where it was unusable until I disconnected and reconnected the RJ11 lead. On the day it was installed, Friday of last week, the engineer and myself were stunned when I said my estimate was 58/18.

Edited by Ixel (Wed 13-Jun-12 16:44:32)

Firstly, forget the error counts as reported in the modem's GUI & only rely on the stats from either direct telnet commands, or the scripts.

The GUI has a couple of known bugs in the way it reports some connection stats.

DLM may never return Interleaving to OFF for your connection (a depth of 1), but given time it may reduce from the current level.

INP & delay are also related to Interleaving/error correction. What are those values (can be seen in the plink log)?

Has Interleaving actually had a negative effect upon your gaming experience?
TBH, I would swap connections with you, right here & now if it were possible.

BTW, the next update to the scripts (expected soon) will include quite a bit more data such as errored seconds etc.

Edited by Bald_Eagle1 (Wed 13-Jun-12 17:15:18)

Thanks for the reply.

Ok I'll ignore the FEC currently being reported, I did wonder if that was a stupidly high value (the millions of them happened after interleaving was made >1 this morning).


INP: 3.00 0.00
delay: 8.00 0.00

Interleaving hasn't had a huge impact on my gaming experience, my ping is still reasonable for my standards of gameplay online (between 25-35ms most of the time). The interleaving depth increased the ping by about 10ms, which is quite good considering.

It's interesting you'd say that you'd swap connections with me right now, if possible, because last night I doubt you would've, I was lucky to remain online for an hour before getting a sudden burst of thousands of FEC and CRC errors, where I had virtually none to worry about before that happened. But I've stated that before.

The next update to the scripts will be good, look forward to it .

I also found a reply on another forum to my problem quite interesting, but I'm still unsure whether I should call BT Business and report a possible fault. With interleaving depth things seem stable now, haven't had a problem all day today but it has also been warm and sunny. For the past few days where I've been experiencing problems it has been raining and cooler. Anyway the reply I'm mentioning is at http://business.forums.bt.com/t5/Broadband-and-inter....

Any other suggestions or what not feel free to add, much appreciated .

EDIT: I have noticed however that bitswapping is increasing on the downstream by 1 every second.

Edited by Ixel (Wed 13-Jun-12 18:20:26)