DLM ISSUES (NEED HELP)

I have recently gone over to AAISP on 21CN and am now experiancing major DLM issues i have had the SNR reset 3 times with no prevail line runs at its normal 5Mb - 5.5Mb for around a day then the DLM kicks in, I have previously been with Eclipse Business and had a IP Profile issue (Permenant restrict to 5Mb despite 6840 - 7000 Kb Sync), Could this be linked??
Any Idea's would be appreciated as i'm going nuts with 2.5Mb

It doesn't just drop on it's own, it's doing it in response to 'something'. Any noise on the line ? What stats does your router show ?

Hi my stats are as bellow during the morning the noise margin can go as high as 18 - 20db
ADSL Link Downstream Upstream
Connection Speed 3072 kbps 1055 kbps
Line Attenuation 47.5 db 24.9 db
Noise Margin 16.9 db 5.7 db

Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 4226908 6323055 0 13211 33551 11:38:10
LAN 10M/100M 5211576 3335704 0 35948 11920 11:39:14
WLAN 11M/54M/270M 4033812 3810342 0 70559 71609 11:38:47

Does This Help??

what's the margin just after a resync ?

Hi I've just rebooted the router and here are the stats just after a reboot.

Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 20 17 0 86 91 00:00:12
LAN 10M/100M 423 416 0 2137 932 00:01:11
WLAN 11M/54M/270M 92 33 0 434 82 00:00:44

ADSL Link Downstream Upstream
Connection Speed 3072 kbps 1016 kbps
Line Attenuation 47.5 db 24.9 db
Noise Margin 17.0 db 5.6 db

BT have just reset the line to interleave again and the noise margin has dropped a fair bit is this normal??

Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 93 87 0 184 691 00:00:32
LAN 10M/100M 5915 6755 0 509 213 01:30:15
WLAN 11M/54M/270M 6894 2691 0 657 64 01:29:48

ADSL Link Downstream Upstream
Connection Speed 3071 kbps 888 kbps
Line Attenuation 47.5 db 24.9 db
Noise Margin 13.3 db 6.5 db

Post deleted by kwikbreaks

Interleaving is a form of error correction so it may be safe to assume that the noise margin can be adjusted accordingly.

Hi all i have had the Interleaving Re - Enabled on the line and rebooted the router here are the stats my ISP also requested BT reset the SNR although this has not happened from what i see. Anybody got any more ideas????


Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 1596 1909 0 1126 6971 00:03:35
LAN 10M/100M 2660 2472 0 6603 1651 00:04:37
WLAN 11M/54M/270M 491 150 0 668 54 00:04:10

ADSL Link Downstream Upstream
Connection Speed 3071 kbps 888 kbps
Line Attenuation 48.0 db 24.9 db
Noise Margin 12.0 db 9.2 db

The thing that stands out to me is that your downstream sync appears to be fixed at 3Mbps. If that is the case it explains why you sometimes have noise margins that don't sit on a 3dB increment immediately after a resync.

When I first saw that I thought you had a very variable level of noise and you had drifted off from the set margin in the short time since you synced but now despite it being very unusual the fixed sync looks more likely. The only way you could get that changed is by talking to a knowledgeable and open minded ISP tech who could in turn speak to a similarly rare rech within BTw - my betting is that this just won't happen even with AAISP

Is there any LLU presence at your exchange?

Hi all it now appears BT have finally reset the margin as requested
Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 2165 2093 0 121 387 00:56:53
LAN 10M/100M 2644 3125 0 430 179 00:57:52
WLAN 11M/54M/270M 5620 823 0 404 27 00:57:26

ADSL Link Downstream Upstream
Connection Speed 4543 kbps 888 kbps
Line Attenuation 47.5 db 24.9 db
Noise Margin 9.3 db 9.3 db

In reply to the last question i have some LLU availible
AOL
Talk Talk
Orange
Are any of these good for high downloaders??? (I average 200+GB a month)

LLU possibilities - I wouldn't use any of the ones you listed. AOL are now owned by TalkTalk who have an appalling reputation for poor customer service should anything go wrong and Orange are moving away from LLU (and theirs was dismal in any case).

It looks like whatever they reset got rid of the "stuck at 3Mbps" issue so whether that was it or it was the margin and all your 3Mbps syncs were a co-incidence we'll never know.

You stats look pretty fair to me me now other than the 9dB target which of course may be needed for stability. Time will tell though.

Good luck.

I've just gone through this on one of my lines, it's 56db and used to be fine on 20cn at 4500-4900 sync. I moved to 21CN and got sync capped to 2272. I got forced down the SFI engineer path to resolve it. He came, rang up some power that be who quoted 11 retrains and stuff but reset it anyway as I explained to the engineer that was me jumping through hoops reporting the fault being asked to reboot routers changed routers and provide screen shots etc. My line failed an asp? test or something with B-E low insulation or something? (was bottom on the list of the test) but it was Friday afternoon and he said he was only allotted an hour and said I would need a new engineer scheduled as his modem wasn't 21CN compatible. So the engineer went I had 4992 sync on adsl1 so left it at that rather than mess with settings. a few hours later I lost sync for 3 days over the bank holiday weekend. faults wouldn't say anything other than we can't chase it as there is an open fault. Line comes back fine for a few hours then it dropped me to 4544, then at 4am it drops me right down to 3072 with a capped sync and 19db snr. My isp arranged another engineer visit (but had down the other was a no show for some reason).
This engineer was completely different and seemed much more willing to fix my problem. He also said his modem wasn't compatible with 21CN but rang some power that be, got 3072 sync limit confirmed and removed checked all the boxes and by some miracle changed my B-E pair? for a new one and its 44db the 1st 24 hours I had 24000 crc errors so I expected a dramatic drop but interleave got switched back on by DLM (engineer had it turned off to do with his modem) and crc errors have dropped hugely and sync gone up to 7611.
The bit that got me was the resulting phone call between engineer and powers that be. The engineer queried the (I assume its bt wholesale or someone on the other end's) notes that my line had 72db loss when it was actually 56, so he updated the records to show the new 44db but said he could still see line errors(crc's I assume) but it was left to see how DLM decided. So far touch wood it's not bitten again.

My observations going through this is that bt have this data possibly for more than just the availability database and the engineers concern over these figures makes me wonder if that database governs to some extent the aggressiveness of DLM as I had much less crc errors before and got limited. The DLM seems to count sync events and data errors (CRC and corrected if the DLM is aggressive enough) and is much more diverse and happy to provide what is stable in its eyes, it doesn't seem to care if our lines were stable for years at 4500 etc I used to tweak SNR in the past and now I have to say I'm almost afraid to even reboot the damned router through fear of DLM shouting fault! and limiting me again. I guess I'm lucky in some ways as there was a fault showing. I'd love to see what a more knowledgeable person had to say about the new DLM and the things it considers before capping a line. The second time my line was limited it was in 1 huge step it didn't even try snr limits.
I know I haven't helped posting this, I just wanted to share what I could glean from my experience of the frustration of DLM on 21CN. And advise anyone who tweaked to get higher sync on 20CN to think very carefully on 21CN.
sorry if I rambled
Dave

So the 3Mbps capped sync is a feature of the 21CN DLM routines then.

It seems that BT have to devise new tortures once their older ones become common knowledge. LLU or cable seem to be the sensible way forward for anyone with the option - I binned BT for cable after losing patience with them a month or so back.

In reply to a post by kwikbreaks:

So the 3Mbps capped sync is a feature of the 21CN DLM routines then.

I binned BT for cable after losing patience with them a month or so back.

That would be a capped or banded profile - its put on to stop the line running away with its self if its ever gets better. I don't have a list of them to hand, but I think they have been posted to the forum before - have a search.

Its ment to 'enhance the user experience' like the entire DLM package its there to cut down the ammount of faults BT have to deal with.

21CN DLM is overley harsh on previousley problem free lines (I'm going through this at the moment) when ever it seen an error it turns the screw as it where.

All you can do is either 1 - let BT keep sending SFI engineers and hope they get to the bottom of it. or 2 - packup now and go over to a full LLU service (if you can) and say good bye to harsh DLM and BRAS profiles.

In reply to a post by IamQ:

Its ment to 'enhance the user experience' like the entire DLM package its there to cut down the ammount of faults BT have to deal with.

Well my user experience has certainly improved since moving to cable and BT can forget all about the line fault on my now abandoned BT line.

heh

Not done much with DOCSIS3 so I don't know how that land ended up - we where an ex cable london area where I am at the moment with was never a good thing...

LLU or cable is the only way to go if BT's system give you problems - I am looking at this at the moment with ongoing issues.

If BT don't get there act together a bit more they will (as ive said before) become the provider of last resort.

thats a good one to stop a line running away when it improves, isnt that supposed to happen on a rate adaptive service?

of course one thing great about these banded profiles for BT/isp's is it gives them full control back, stops users overiding it with snrm tweaks.

agreed, cable isnt perfect, but (a) its very stable compared to my adsl and (b) even with the bits of congestion the average throughput is over triple of my adsl.

in terms of technical support on faults, I was able to get a VM tech out to fix a power issue on my modem the day after I called with no arguments and loops to jump through.

Edited by Chrysalis (Fri 11-Jun-10 00:30:05)

The daft thing about my fault was that I wasn't complaining about the ADSL side - as I was on O2 LLU and not subject to BT's moronic DLM a quick reboot sorted that out albeit with slightly less speed than the line should have provided - I was complaining because the actual voice was (intermittently) unusable.

In some form of luck of miracle I have had the line tweaked i believe by AAISP, Its managed to hold a 6DB Sync for a good 6 days now but got home from work today to find this resync:

Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 21268 33973 0 627 10164 01:12:20
LAN 10M/100M 9556 9472 0 1503 422 01:13:27
WLAN 11M/54M/270M 38395 17501 0 9490 528 01:13:01

ADSL Link Downstream Upstream
Connection Speed 7214 kbps 888 kbps
Line Attenuation 48.0 db 24.8 db
Noise Margin 2.9 db 8.1 db

Is this part of the new DLM or have BT just plain messed up????

In reply to a post by spongebobhims:

Is this part of the new DLM or have BT just plain messed up????

Thos first set of stats confused me some what all squished up.

So your now back on a 9db profile, and it looks like the max rate (reported) is 11mbit but your sync is only 7.2mbit ?

Smells like DLM to me - this is the problem I am having at the moment. A line will be good for a long time, then bang 1 resync and I start working up the noise margins again..

You line is longer than mine and you are still getting a higher synch then I have seen in months.