Strange BT explanation for slow line ?

Well, BT were here for the 12th time in 3 months this week. They claim to have switched my line to a copper pair, but little has changed in the way of performance.

However, the engineer did make an interesting statement - he said that the ADSL signal leaving the exchange on my Zen business connection was only 5Mbps, instead of 8Mbps. He said if the full 8Mbps was available, I would probably get another 2Mbps. Now, I would have laughed this out of hand, were it not for the fact that when I switched my domestic line serving the same premises to Sky LLU, the speed went up by 2Mbps (and my Sky is ADSL, not ADSL2+) !

Are BT making it up, or is there something in this ?

is he saying that connecting to your line on the frame at the exchange it only gets 5M ? if so there would appear to be some issues within the exchange or on the DSLAM.

?
So your Sky Max is tweaked down to ADSL and gives 3864kbps, which is 2Mbps above what you got before. So you had 1800kbps, but another line gets 5Mbps and you have been told should get 7Mbps?

Maybe full stats on both lines might help, plus a BT speed test on the 5Mbps one to show the profile.

In reply to a post by yarwell:

is he saying that connecting to your line on the frame at the exchange it only gets 5M ?

I think that's what he's saying.

The Sky Max is an LLU service, Roberto, so it doesn't have a line profile, nor can you do a BT speed test on it. The BT guy put his router on it, and he said that it was sync'ing at 5Mbps.

The engineer implied that he was only getting 5Mbps when connected at the exchange, and if he could have got the full 8Mbps, I should get another 2Mbps on the Zen line, which is 3Mbps on a good day. Previously the Sky line was with Zen, and it only scraped about 2.5 to 3Mbps.

narrows down the location of the problem if he only gets 5M at the exchange. Should get 8M on a cab 2km away !

In reply to a post by yarwell:

narrows down the location of the problem if he only gets 5M at the exchange. Should get 8M on a cab 2km away !

Going by attenuation my house is 2.6km from the exchange and I always got 8128. Now that I'm on Be it varies between 12.7Mb/s during the winter months and 13.5Mb/s during the summer. I do have to run with a slightly raised margin though. I think on the default 3db it sync at just over 14Mb/s but will suffer three or four LOS an hour.

Edited by Andrue (Fri 04-Sep-09 14:45:45)

Going by attenuation my house is 2.6km from the exchange and I always got 8128

Ditto, 2.5 km I can follow it by bike with GPS and 8128 sync with 7 - 10 dB margin.

here is my take.

its become evident DLM on 21cn lines as well as having target noise margin raised can also have synch speed capped. Now a lot of if's.

if your line is on 21cn
and if your line has been capped by dlm.

it is possible the synch is capped to 5mbit and then the engineer seen that behaviour at the exchange.

are we talking direct or crow distance?

crow distance is hardly a reliable way to estimate speed, I am 1.65km crow distance and have a 49-50db attenuation with a synch of around 5.2-5.6mbit on adsl1 with current line conditions.