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[roseway]

I've been having a bit of trouble with my connection recently (an intermittent HR fault) and look what DLM has done with the interleave depth:

Code: [Select]

DSL mode: ADSL2+
Status:  Showtime
       
  Downstream  Upstream
Attenuation (dB):         44.5       24.7
Connection speed (kbps):  6653       1024
SNR margin (dB):          4.9       5.6
Power (dBm):              0.0       12.8
Interleave depth:         352       4     

[kitz]

>> Interleave depth:         352

That surely cant be a true interleaving depth or your latency would be awful?
What are your throughput speeds and latency like?

I could be entirely wrong, but that could perhaps indicate some sort of fixed profile?  Waits to see if anyone else has anything to add.

[kitz]

hmmm   maybe not.   

Ive just done a google and I cant find anything, but I have found someone on Be* reporting the same depth, when they say they're on the optimised for speed profile (3db) with gaming mode switched off.

So now I have no idea.

[roseway]

There isn't a problem with latency:

Code: [Select]

eric@chaffinch:~$ ping bbc.co.uk
PING bbc.co.uk (212.58.241.131) 56(84) bytes of data.
64 bytes from 212.58.241.131: icmp_req=1 ttl=247 time=28.0 ms
64 bytes from 212.58.241.131: icmp_req=2 ttl=247 time=28.3 ms
64 bytes from 212.58.241.131: icmp_req=3 ttl=247 time=28.6 ms
64 bytes from 212.58.241.131: icmp_req=4 ttl=247 time=28.6 ms
^C64 bytes from 212.58.241.131: icmp_req=5 ttl=247 time=28.5 ms

--- bbc.co.uk ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 20250ms
rtt min/avg/max/mdev = 28.080/28.448/28.655/0.307 ms
eric@chaffinch:~$

But the speed is lower than it should be (I have been getting a stable ~8600 kbps) so I wonder if the very high interleave depth may be depressing the speed. Speedtest.net gives me an actual download speed of just on 6 Mbps.

[roseway]

I've just done a full reboot of the router, and the stats shortly after booting are shown below. It definitely looks as though the interleave depth is depressing the downstream connection speed:

Code: [Select]

DSL mode: ADSL2+
Status:  Showtime
       
  Downstream  Upstream
Attenuation (dB):         44.5       24.7
Connection speed (kbps):  6653       1052
SNR margin (dB):          6.4       6.4
Power (dBm):              20.4       12.8
Interleave depth:         352       4     

[kitz]

I do have some comments on this, but head is full of other stuff atm.

d'oh its depth not delay..  so yes it will impact your speed rather than latency.

[burakkucat]

The simplest thing would be to get the HR fault fixed and then see if the DLM reduces the interleave depth. 

[asbokid]

Hello Roseway,

Maybe DLM has adjusted the interleaving depth to try and mitigate for line noise?  i.e. break up the ATM cells, spread them out (interleave them) and hopefully brief impulses of noise, just a few milliseconds in length, corrupt less data?   Does QLN show anything abnormal?

cheers, a

[roseway]

The simplest thing would be to get the HR fault fixed and then see if the DLM reduces the interleave depth. 

You're right of course, but this fault is very intermittent, and has been coming and going for years. I've made several attempts over the years to have it fixed, but what has always happened is that, by the time OR test the line the fault has gone and they can't find anything wrong. On one occasion I got a bill for £188 for a NFF callout. I know I don't rate very highly in the persistence area, but I've taken to weathering these little storms without complaint.

[roseway]

Hello Roseway,

Maybe DLM has adjusted the interleaving depth to try and mitigate for line noise?  i.e. break up the ATM cells, spread them out (interleave them) and hopefully brief impulses of noise, just a few milliseconds in length, corrupt less data?   Does QLN show anything abnormal?

cheers, a

This is undoubtedly what it is. The error rate is quite high, although the connection has until very recently been extremely stable, even with a target SNR margin of 3 dB. Until about a week ago, DLM was forcing my connection to fastpath.

I don't really know how to interpret QLN data, but the current situation is below, as well as the FEC rate.

[Azzaka]

The depth could be due to a 3-6mb profile being placed on the line with INP level 2.

I would report the issue as a fault and if all basics are completed you will have nothing to worry about when it comes to charges. If the ISP tries to charge, then I would personally dispute it with them and BT.

[roseway]

Thanks Azzaka.

[Azzaka]

Let me know how it goes

[roseway]

I fear I may have unintentionally given the wrong impression here. My intention was to report a curiosity, rather than to seek help. As it happens, I've already decided to escape from the clutches of BT's DLM system and migrate to Talk Talk who have recently LLU'd our local exchange. As a bonus, this will also save me more than £20 a month.

My apologies to those who tried to help.

[burakkucat]

As it happens, I've already decided to escape from the clutches of BT's DLM system and migrate to Talk Talk who have recently LLU'd our local exchange. As a bonus, this will also save me more than £20 a month.

Welcome to the club.

As soon as your TT service is active, sign up to the Members' Forum and request that the DLM be disabled on your line.