DLM not resetting in FTTC

Hi All,

I had a line problem a few months ago (literally). After months of intermittent HR issues, the line completely failed. An OR engineer was dispatched and it was fixed, however since then my line is stuck at 67/19, when the attainable is ~74/20.

I know that DLM takes time to reset, but months having passed, I think something's wrong. The router is up and stable along with the line.

I asked my ISP (Zen), and they were unusually unhelpful.

Anything I can try?

Cheers,
AP

It's very rare that you will get the attainable rate.

What is your noise margin?

It's 8db on the downstream. I used to get the max attainable until all this happened.

You'll be within the estimated range for your line so I doubt they'll be willing to do anything.

Could we have the full stats please?

How long since you rebooted the modem or router?

Current uptime is 21 days. I hope this doesn't format horribly:

Max. DSLAM throughput kbit/s 67000 19000
Min. DSLAM throughput kbit/s 128 128
Attainable throughput kbit/s 74701 20229
Current throughput kbit/s 66997 19000
Seamless rate adaptation off off

Latency fast fast
Impulse Noise Protection (INP) 43 0
G.INP on off

Signal-to-noise ratio dB 8 6
Bitswap on on
Line attenuation dB 16 23

Profile 17a
G.Vector off off

Carrier record A43 A43

That's the problem. I suppose I should have gone down the broadband fault route, rather than the voice fault route when reporting the line down.... :/

That looks suspiciously like banding was applied and not removed by the engineer requesting it. But so far as I know 67,000 is not top of a band.

Edit - I see you had a phone engineer, not a broadband one. Nothing would have been done about the DLM then.

Edited by RobertoS (Tue 02-Aug-16 16:54:29)

Reboot the modem!

I've tried that a few times, hence why the uptime is only 21 days, and not months.

I read that DLM should reset early in the morning, causing a resynch, but it's not happened for me.

You're spot on, but can anything be done about it now, short of snipping the wires coming into the house!

Are you connected to a Huawei cabinet, meaning that G.INP is available to you?

According to the supplied stats download G.Inp is on. It does look like a banded line.

Ah yes, misread that. Thanks

All you can do is wait , the DLM can take a long time to revert your line back to what it was before.
The line might have a problem with crosstalk or some other problem that might not be easy to find , for example the wet weather we have had might have made the pair to the cab damp or even the cab it`s self could have an intermittent fault.?
It took the DLM 4 months to sort my line out after a power cut about a year back.

4 months?! I'll put a note in my diary for 2019 to check.....!

I am not kidding, that DLM is a pain once it gets at a line it never seems right again imo.
The trouble is the darn thing does not know the difference between a line fault and a simple power cut.
Personally I do not see why it is needed as a good line will always return to the way it was before a cut of power.
And if there was a real bad line then the DLM is pointless anyway.?
The cabs themselves can cause the DLM to trigger too because all motors [fans etc] cause interference and so does passing traffic if the cab is near a busy road.
IMHO they could do with more shielding in the cab to stop internal EMI [Electric Motive Interference].
Getting of the soap box now.LOL.

Edited by deleted (Tue 02-Aug-16 23:21:01)

Currently, DLM seems to be exceedingly reluctant to ever remove banding. And considerably keener to put it in place too.

There's a good chance that you need to get Zen to organise a DLM reset, justified as a consequence of the previous voice fault fix. It'll need an Openreach engineer appointment.

The current likelihood is that a DLM reset will initially start on an interleaved profile, so your speed wouldn't be likely to improve, and your latency would get worse. Then, in theory, it would swap back to fastpath after 2 days, and then, eventually back to G.INP. That process and timing depends on error rates, and predictable DLM behaviour.

Unfortunately, DLM is not currently behaving predictably, and you run a risk of finding yourself stuck interleaved with higher latency.

With DLM in its current guise, I'm not sure I'd recommend chasing the extra few Mbps right now, unless you really, really need it.

My line had was banded at 67,000 then 60,000 kbps, even with a 10db noise margin, the 67mb banding was there for a year with a 7-8db noise margin, the 60mbps banding was about 5 months with a 9-11db noise margin.

It never got better, only worse with the next fault that caused the 60,000 banding in the first place.

IMO banding virtually never gets dropped without a DLM reset.

I think I have 60,000kbps banding. I was stuck exactly on it for ages, through several re-sync's. Now I can't get to it .

In reply to a post by Ragnarok:

My line had was banded at 67,000 then 60,000 kbps, even with a 10db noise margin, the 67mb banding was there for a year with a 7-8db noise margin, the 60mbps banding was about 5 months with a 9-11db noise margin.

It never got better, only worse with the next fault that caused the 60,000 banding in the first place.

IMO banding virtually never gets dropped without a DLM reset.

Ragarok and the other posters have a point , it sounds like the OP [AndyPandy] has a banded line and the DLM is going to take a while to sort it out , unless the DLM is reset by OR.
Maybe playing the waiting game might be the best.?

Unfortunately Zen have not been helpful. Whilst the guy did say he'd "go away and talk to people" about getting an OR visit, he eventually came back and said they wouldn't.

Hard to justify the extra money spent if the support is sliding.

It looks like I'm probably stuck with it, unless another fault occurs, and I'll be sure to raise it as a BB fault, not voice.

It's not slow, it's just frustrating to see that extra speeds there, that I used to have, being "wasted". Hopefully the pending changes to OR's business model will make them more responsive to the consumer.

Having to physically visit a cabinet to perform a software reset, to an internet connected device, is stupid however.

In reply to a post by AndyPandy:

It's not slow, it's just frustrating to see that extra speeds there, that I used to have, being "wasted".

This sort of thing is the reason Openreach locked the modem so the stats aren't available.

What is involved in a DLM reset? Surely nothing that couldn't be achieved by the ISP in the first place, by pressing a few buttons. If it hard wired into a card, what century was the card built! i.e. travelling distances to reset something is '70s technology.

As it is, if DLM reduces the line for no real reason then it's a win win situation for OR (they aren't shifting so many bits) and the customer loses out. I certainly feel that way. Unfortunately having used the BT line test, it says my IP profile is 66.82Mb and Plusnet have me at 67.4Mb. Even though it will go quite above back towards what I used to get. recent speedtest - Speedtests before DLM reduced the line There's nothing wrong with the line, just a naff system that likes to restrict customers. I got told it would reset after 72 hours but still waiting after a week and a bit. Looks like I'll have to wait for whatever it was that reset it last time. Maybe I need to put a UPS on the modem!

The engineer calls a number to request a reset and it gets done remotely.

The suggestion an engineer needs to visit the cabinet wasn't entirely correct.

It is or certainly was for years Openreach policy that DLM resets are only carried out at the request of an engineer after being called out to, and supposedly fixing, a fault. For a long time he couldn't trigger it directly himself either. He had to call his control centre and request it, and sometimes they would refuse.

I seem to remember something has changed in this policy in the last few months, but can't recall what sorry. Possibly the ISP can now request it, or at least the underlying provider - BTW/Sky/TT/Voda.

Yuk!

We overlapped .

Are you overlooking that FTTC cabinets have Battery Back-up to cover something like 8 hours?

I have actually seen them in the local FTTC, Huawei 288, when a faulty battery was being replaced.

In reply to a post by AndyPandy:

Unfortunately Zen have not been helpful.

I don't monitor the Zen forum here, but the number of very similar unsatisfactory responses from them we see in the non-ISP forums on this site over the last couple of years or so ruled them straight out of consideration when I left Plusnet. I forked out for 100GB allowance on AAISP instead.

Zen rarely seem to put up any fight against OR or BTW when a retail customer has problems like yours. I assume they are different with (true) business ones.

The engineer calls a number to request a reset and it gets done remotely.

Oh yes, a task most easily done ......

Not to bump this, but I thought it worth an update.

After 50+ days of solid synch, DLM finally re-synched me on an open profile. Can't believe it took that long, or that it finally happened either.

Back to 80/20 max, and getting 72/20, rather than 68/19.

The difference you can see must be astounding.

Now up to 74/20

In reply to a post by AndyPandy:

Now up to 74/20

Wish I could get a reliable 0.74/0.2 !!!!! never mind more

In reply to a post by AndyPandy:

Not to bump this, but I thought it worth an update.

After 50+ days of solid synch, DLM finally re-synched me on an open profile. Can't believe it took that long, or that it finally happened either.

Back to 80/20 max, and getting 72/20, rather than 68/19.

Mine seems to have been hit by the engineers installing a second cab. Sync dropped from 70Mb/s to 60Mb/s (oddly without dropping my PPP connection). Dunno how long it'll take to bounce back but no point trying to prompt it. The engineers have been there over a week now. They've even put tents over the PSTN cab and the new FTTC cab.

I'm surprised it's taking that long for them to install another cabinet.

In reply to a post by AndyPandy:

Not to bump this, but I thought it worth an update.

After 50+ days of solid synch, DLM finally re-synched me on an open profile. Can't believe it took that long, or that it finally happened either.

Back to 80/20 max, and getting 72/20, rather than 68/19.

That's a long time for DLM to restored your sync rate back. Mine only took 42 hours last year to restored back when DLM reduced 79999/20000 to 63999/20000 because of my own fault of swapped too many diffrerent router and modem without power down for 30 minutes.

Edited by adslmax (Wed 14-Sep-16 18:32:59)

Sheesh. Came home tonight and now another van has turned up. They aren't BT - it's one of their contractors 'Cass' I think. They've also opened a manhole cover on the opposite side of the roundabout and were poking about in there. Blocked off half the main road into our estate and causing chaos.

Surely it shouldn't be that difficult to install a second FTTC cabinet. The hard work is already done isn't it?

Edited by Andrue (Thu 15-Sep-16 08:39:42)

In reply to a post by adslmax:

That's a long time for DLM to restored your sync rate back. Mine only took 42 hours last year to restored back when DLM reduced 79999/20000 to 63999/20000

You did very well. It can and does take many months for DLM to relent.

In reply to a post by kasg:

In reply to a post by adslmax:

That's a long time for DLM to restored your sync rate back. Mine only took 42 hours last year to restored back when DLM reduced 79999/20000 to 63999/20000

You did very well. It can and does take many months for DLM to relent.

DLM is now very slow to relent, and sometimes never does. It didn't always act this way. @max's experience is, unfortunately, an outdated one.

In reply to a post by WWWombat:

In reply to a post by kasg:

In reply to a post by adslmax:

That's a long time for DLM to restored your sync rate back. Mine only took 42 hours last year to restored back when DLM reduced 79999/20000 to 63999/20000

You did very well. It can and does take many months for DLM to relent.

DLM is now very slow to relent, and sometimes never does. It didn't always act this way. @max's experience is, unfortunately, an outdated one.

Well that cheers me up no end. Is there a way to request that 'The stupid pillocks messing about with my cabinet put things back the way the found them when they're done?"

Probably not

In reply to a post by Andrue:

Well that cheers me up no end. Is there a way to request that 'The stupid pillocks messing about with my cabinet put things back the way the found them when they're done?"

AFAIK only by way of an engineer visit following a fault report.

Why is DLM take much quicker to reduced speed but take a very long time to restored it back, sometimes never happen? Perhap BT like everyones on a slow snail as long DLM take it forever!

I suppose mine is outdated

Edited by adslmax (Thu 15-Sep-16 18:41:12)

In reply to a post by kasg:

In reply to a post by Andrue:

Well that cheers me up no end. Is there a way to request that 'The stupid pillocks messing about with my cabinet put things back the way the found them when they're done?"

AFAIK only by way of an engineer visit following a fault report.

Le sigh. Well they were still there tonight. Talk about making a meal of it.