Why is this happening?

Noticed my line keeps switching from interleaved to fast path. I force it to run on ADSL2 via my router and it randomly keeps dropping during the day.

When I check why it is dropping it keeps going from interleaved to fast path.

I've opted into interleaving on my ISP's portal.

Why is the DSLAM playing around with my line??

It's the DLM discovering that your line is stable enough to handle Fast Path.

What ISP? At a guess one delivering BTw WBC, maybe.

However, if your ISP provides a means of specifying Interleaved on their portal, they should honour it and program DLM accordingly.

I'm with Xilo on 21CN WBC.

I thought that because I am 'Opted IN' it would run all the time?

You need to speak to Xilo.

I'm also on WBC but my ISP says it's auto by DLM and they can't change it, but we don't have a user settable portal like you.

I also wanted Interleaved, but I've settled for Fast Path as the error rates are low.

On the original DLM, it was possible to specify Fast Path or Auto. Auto defaulted to Fast Path, and the DLM switched to Interleaved if it decided it was needed. It never switched back if circumstances changed.

If Fast Path was specified it didn't switch to Interleaved.

I think it's possible that there are two factors causing your problem.

First, the new DLM (as well as having instant IP Profile changes and a 3dB noise margin setting), is clearly able to revert to Fast Path.

Second, the option in your ISP's portal may be mis-labelled and means "Auto" as above.

How do you get it back to Interleaved, and is there a setting in your router you could use? Possibly via telnet?

This isn't good news.

I'm on a 3db profile at the moment, router forced to ADSL2 connecting at around 6700kbps @ 48.5db attenutation.

Recently it's been dropping during the day, which the line never does. Pretty sure it's DLM doing it.

The only way I can get it back to interleaved is by pulling the plug on the router at 8pm but then it re-syncs at 5300kbps.

It's a noisy line at night, it goes wild on ADSL2+ and without interleaving the pings rocket to over 100ms.

If Xilo can't do anything, would moving to LLU like Sky help?

I have opened a ticket with them.

Unfortunately my line is quite long and noisy at night. Without interleaving i'll probably end up with a 9db/12db SNR.

In reply to a post by wolvesmad:

without interleaving the pings rocket to over 100ms.

Surprised latency increases with Fast Path.

During the day the ping is 11ms. At night 100ms.

See the BQM in my sig, (on Plusnet fTTC), and also this BT thread. If your latency problem is recent, it could be part of a wider issue.

@btcare tweeted something about problems with sites recently too

In reply to a post by wolvesmad:

I have opened a ticket with them.

Unfortunately my line is quite long and noisy at night. Without interleaving i'll probably end up with a 9db/12db SNR.

For 21CN ADSL2+ your long noisy line MSAN should be set to minimum download noise margin 6dB and interleaved path to obtain a stable connection, 3dB-noise margin is too low.

http://en.wikipedia.org/wiki/MSAN

3db is solid interleaved on ADSL2 - 30 days + uptime.

In reply to a post by wolvesmad:

3db is solid interleaved on ADSL2 - 30 days + uptime.

Huh? I thought it was randomly dropping?

EDIT: Re. Interleaving as others are saying your ISP should be able to 'pin' this.

Edited by b4dger (Tue 09-Oct-12 16:26:53)

Can you confirm if you sync on adsl2 or adsl2+, as even the mode on your line by the sounds of it could make a significant difference, are you able to force Adsl2 mode ? If it wasn't 21 cn wbc i would say try adsl g.dmt (upto 8mb) but as i don't know too much about 21cn and the available config options,
The rising ping during night time sounds like congestion local to you(exchange ) or vp

WBC should let you force g.dmt if the modem gives the option. I usually try it on the modems I have to see if it works

In reply to a post by MrSaffron:

WBC should let you force g.dmt if the modem gives the option. I usually try it on the modems I have to see if it works

In that case i would be trying the G.dmt mode , on a longish line like that, certainly nothing to loose by trying it, The op may get the best of both worlds a higher sync rate and fast path , giving a connection that is stable too

Edited by tommy45 (Tue 09-Oct-12 17:54:18)

I force ADSL2 which has been VERY stable on a 3db SNR margin - when interleaved. Unfortunately, it is a noisy line at night, always has been.

Xilo have been excellent as usual. BT have reported back asking for line stats as from what they can see, the line is in interleaved mode and at Xilo's end, i've opted in on interleaving.

It was DLM dropping the line during the day, changing the mode from interleaved to fast.

Prior to that, it had been up for 38 days at 6100kbps.

3dB margins are really only meant for lines that don't have night time noise issues.

Hence why it was a late change for BT Wholesale to squeeze more speed for the those in good areas