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[MagicMike]

Hi all

I know there are loads of postings about the performance of ADSLMax and I am (generally) getting decent download speeds and no dropouts (it ain't broke, don't fix it?), but I have so many FEC errors I think something must be wrong. I can see the SNR margin is lower than recommended as well. Any advice, please?

All the computer equipment, sadly, is the opposite end of the house to the main telephone socket. Extension cabling is Cat5. Microfilters in place on all sockets.
Attached image is from the line stats of a BT Home Hub. Interleaving is on. I'm 700m from the exchange and on day 13 of ADSLMax (so should be past the training period for the line)...
The 2Mb line i had before Max was absolutely rock solid.



[attachment deleted by admin]

[kitz]

Hi

Without even reading your post properly, the first thing I noticed about your stats was the sync speed of 8096, and thought interleaving is on.
There is something weird about the sync speed of 8096 in that it causes the highest latency of all the profiles, and it has the highest error correction rate.
Based on observations.. Interleaving and a large amount of FEC errors also seem to go hand in hand on some lines.

TBH your attenuation is a bit higher than I would expect for being 700m away - but  it depends on the routing of your phone line in between your home and the exchange.

Try plugging your hub into the master socket to see if your attenuation and SNRMargin change.
Even better try it in the test socket behind the master socket as per the instructions here:
http://www.kitz.co.uk/adsl/troubleshooting.htm

7.5dB SNR is ok..  does it vary much from that?
Monitor it for a few days - particulary in the evenings and see if it drops any lower.

Based on your line stats.. (if your SNR doesn drop too low).. then your line probably doesnt need interleaving switched on, and may well perform better with it switched off.
Interleaving works pretty damn well on some lines.. a few perform better without it.

It may be worthwhile you reading this thread where ES was seeing something similar.
http://forum.kitz.co.uk/index.php?topic=169.msg5459#msg5459
Although bear in mind that ES had a bit better SNR Margin than you have.

If your SNR Margin doesnt drop much lower than 7dB, then Id contact your ISP and ask if they can permanently turn interleaving off on your line.

[EVIL-SCOTSMAN]

Personally, I think its the hub thats the cause of the problems, thats why I think I was put on interleaving in the first place, as I noticed that each time I reset the bt home hub, some times it would be perfect and other times it would give me thousands upon thousands of errors, without any changes to the line being done within the 1 minute it takes to reset the hub.  BT collect the error information and adjust your line accordingly, so I and maybe I am wrong, I seriously think that the bt home hub is the cause of my problems, and maybe also yours ?

Dont take my post as the gospel truth, as my experience may not be the same as yours, but with your profile of 8096 means that interleaving is turned on, as it was in my case and I was syncing at 8096, I got interleaving turned off, and i then started to sync at full speed 8128, the hub then continued to give errors, so i swapped it for one of my other routers, and I havent lost sync nor had 1 error in 4-5 days.

I gained 200+ kbytes  not bits of speed after interleaving was turned off and couldnt be happier. 

Bottom line is, errors in the hub, bt equipment monitors them and changes your line to be more tolerant or whatever, even tho your line "may" not be the problem, thats what I suspect, lots of people have faulty hubs, so I personally think they are to blame for a lot of ppl's problems, I am only going by my own experience, so I cannot say if you are having the same experience as me...

I would like to add, if all your errors are download errors like mine and not upload errors, then I seriously suspect it could be the hub not being able to cope with the info and causing the errors itself, if you have another router spare, connect that and see if  that also gives you the same amount of errors over a given time, you will always get errors with interleaving on, but since you have millions in a short space of time, try another router and if you only get a couple of hundred, then you can be assured its a dodgy home hub.

FEC = interleaving on,  CRC = BAD,  you will never be able to get rid of the FEC errors with interleaving on, but with another router you may find that the amount goes down and also you may not even get the bad CRC kind at all, I have 4 routers, and only the bt home hub was the one to give me the CRC and HEC errors, the rest dont, and they dont lose sync like the hub used to.

[roseway]

You shouldn't forget that FEC = Forward Error Correction. It's a system whereby extra information is sent along with the data, which enables most errors to be corrected without retransmission of the data. The FEC error count represents errors which have been corrected in this way, and which would have required retransmission without the FEC capability. It's quite normal for this error count to be millions per day, and really is of little concern if your connection is stable.

Eric

[EVIL-SCOTSMAN]

As you say, FEC = Forward error correction, so any info that is transmitted that gets corrupted will be corrected byt he router.

But, this is what I noticed with the home hub, after turning the home hub on and off, sometimes it would give 1 or 2 errors over 5 hours or so, and the next time it would give hundreds of thousands.

It is normal with interleaving to get FEC errors and they are nothing to worry about, but if you get hundreds of thousands or millions, BT's equipment detect that and then adjust your line accordingly, when if it is a case of the router's firmware being crap or basically just a crap router, then BT can mess with your line when infact the router is the cause of the problem, thats what I found out.

When i first got activated with btmax, my bt home hub arrived at 7am, but i was still in bed, so I nevver got it the day my line was enabled, so I used a z00m x4 which only syncd at 79** but on fast mode, I had no errors and no resyncs at all while using it, I noticed that I wasnt getting the max sync speed, so I plugged in my livebox, it synced at 8128 staright away but I couldnt surf due to the livebox being locked to wanadoo. I then put the zoom x4 back in and it still synced at 7900 odd but it was a good connection with no interleaving and no errors, 2 days later I got my home hub, then thats where all the problems began, it would resync if I sneezed basically and within seconds of me first attaching the home hub, I got errors and then my line was changed to interleaving ?

I wasnt worried about the FEC errors as they mean the info has been sorted by the router and it hasnt asked the server to resend, but the crc errors and hec errors I never got with anything else except the bt home hub, I just think the home hub is a twitchy piece of kit, some times it performed with no errors, then a reset or reboot and it would throw up thousands.

Thats my personal opinion anyhow, I maybe completely wrong and maybe infact it could be all my other routers that are borked and the home hub was the only one showing the correct info ? doubtful but could happen.

After reading of people getting 5 and 6 replacement bt home hubs and my experience, I tend to think the home hub is a cheap piece of kit that is only good for pc users who dont really know anything about pc's, as long as they get connected to the internet they are oblivious to what the settings and stats on there router mean....

Going by my problems, I wouldnt exactly quote having millions of FEC errors aday is quite normal and nothing to worry about, it was proved now that my line has 0 problems, but the router was throwing up errors by the bucketload, I would only expect that amount of errors to affect someone that is like 5-6k away from the exchange or someone with a really shaky line, as the OP stated, he practically lives on the exchange, ok that doesnt mean anything, as various factors are at work, but I tend to think that someone close to an exchange would normally have a decentish line.

As I say to the OP before, try another router if you can and see if the errors will atleast be lower, the fec errors will probably always show up and are nothing to worry about as you are on interleaving mode instead of fast mode, but with another router, you may only get a couple hundred aday like I did, and no CRC and HEC erros at all.

I hope you get it all worked out, as it took me a while to get threw to BT to get things sorted, basically interleaving being turned on for me was the root cause of all my problems, how it got turned on after 2 days of stable use with no errors and decent sync speed, then 30 minutes of using the home hub it got turned on is a mystery, but now its off I get no errors and highets possible sync speed and this as my speed test, and I am 1.5km away from the exchange and my exchange is congested, it was supposed to be upgraded yesterday, 13th october, but that was only a provisional date.

Download Speed: 6905 kbps (863.1 KB/sec transfer rate)
Upload Speed: 314 kbps (39.3 KB/sec transfer rate)

compared to 500-650 max before.

[MagicMike]

Hello again and thanks for the input so far.

It may be well be a dodgy home hub. When BT "maxed" me, they said the upgrade would go through after 7 days but the hub wouldn't come for 14! (Both of these were correct). So in the meantime I bought a cheap router off eBay, a Safecom GART-4112, and used that for my first week of Max. I can't say I remember seeing so many errors then - perhaps I'll plug it back in to check.