FTTC and DLM

Has anyone fallen foul of DLM on FTTC yet?? I have had 1 line since October 2010.... was fine, well in aspect of synch....throughput V.POOR!! ISP blamed BT but since then i know thats not the case always!!

But my main question is.......Has anyone had a line problem and got their SNRM/Profile reset as my ISP says it can't be done! I think thats rubbish..... but ....... i don't know 100%

My second line has a profile of 38,717 and when installed had a SNRM of 16dB as did my first line, but now i can't get anything above 37,133...... not the end of the world .... I know but annoying!!!

If anyone has had their profile reset it would be nice to hear from you!

Cheers

Dave

What are you on about? (In as friendly a tone of voice as possible for that question).

Which ISP for starters? That may give a clue, just like it does on ADSLx. Not all throughput provisions are equal. Your profile says O2 LLU. Is it IDNet, where you mentioned the subject in November?

If you read this thread it long ago went slightly off topic and into the FTTC DLM in general. Billford's posts are particularly useful, and he's in IDNet FTTC.

You are really wondering where that profile has gone? Or do you mean download speed? (And by the way I find the sentence where you give the profiles baffling. Which line has what profile, as you seem to say the second line has 38717 but can't get above 37133). I get the impression you may have been playing around with reconnections and so on, which could be bad news given what is in that thread.

Where do you get the SNRM values from? I don't think anyone else has managed to find any stats at all.

there's more than one option for the DLM for starters, so ask the ISP which you're on.

In reply to a post by yarwell:

there's more than one option for the DLM for starters

Got any details yarwell please? I'd like to get myself clued up on it.

shall I Google it, or shall you Stable, superstable and standard from memory. Openreach NGA docs.

Section 3.2.3 of SIN 472 (WBC) issue 1.8 talks about the three options.

the thing I quoted earlier "2.2.5 Dynamic Line Management
Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly
manages lines to maintain a target stability. It does this for as long as the product
exists." is the FTTC specific bit, I believe from a training doc that the three options apply to FTTC as well so presumably Openreach's DLM on FTTC has a set of parameters to match the three wholesale options.

Edited by yarwell (Sat 22-Jan-11 13:43:01)

That's great thanks, enough to go on . I just wondered if you already had more detailed links.

We have the same standard, stable and super stable options on FTTC as we do on 21CN ADSL2+ and they are supposed to be similar in how they work. We've not done any DLM profile resets ourselves but have seen them done by Openreach as part of fault investigations.

Firstly thanks for all the replies.

Sorry i should of made it a lot clearer. About 150 metres from Cab in a straight line Attn of 7dB on both lines.

Line 1 - IDnet installed Oct 2010 when installed had max sync and SNRM of 16dB
Line 2 - BT Infinity installed Dec 2010 when installed had max sync and SNRM of 16dB

I only know this as the nice BTW engineer(s) showed me on his hand held JDSU (i think thats what they called them!)

Line 1 - now is the one that seems to have a problem, after the second line got installed the profile dropped to 37000 ish...... I have rebooted the modem once a week to see if its got any better!!

I can't believe i have lost 10dB snrm? or maybe i have? Hence why i think DLM has kicked in. I will ask IDnet the question as to what i am currently set to.

I have had many thoughts on this....

1. Cross Talk (but the other line that runs in the same cable is fine)
2. They had to "tone" the line to find the pair at the other end and i take it that would of caused errors? and started DLM
3. We had to disconnect the line and the power a few times as i now have 8 plugs buy my 2 phone lines/FTTC lines

A comparison of the 2 lines after 1 month....... BT out of peak hours 6-12pm 37mbps all the time....dips to 20mbps lowest i have seen (fingers crossed it stays like that)

IDnet better now than in the first few months....... but after 12pm it can go as low as 5mbps with pings of 120ms when there off peak kicks in! Generally good at peaktimes now! But was dire in the first month.

Hope that makes sence!

Cheers

Dave

Hi Dave,

Do you know what the difference is with the 3 profiles?


TIA

Dave

That's a lot more understandable, apart from a random fact that you throw in .

I get the feeling there are three issues.

First I think the second line or someone else's FTTC will be the cause of the lower sync/profile on the first. But there could be some sort of fault. With the little we know so far about FTTC it's impossible to know.

It isn't likely to be different routes back to the exchange, that's all we can almost certainly rule out, but don't forget from the fibre cab back to the old cab is copper, and on to you from there is all old copper and line proximity. Your two-pair line only goes as far as the pole or first junction box, and the two can then go differently to the cab.

Second, it is highly possible that IDNet backhaul provision was inadequate in the early days. Getting WBC handover capacity right is a nightmare on WBC, and not easy on WBMC. I don't know which they use, probably WBMC. (See my website for the difference). They have probably added a fair bit.

Third, BT Broadband ADSLx and FTTC does seem to suffer from considerable congestion, as you say, but they have tools in place to ease the pressure by throttling the biggest demanders. IDNet do not, so far as I'm aware. At congested times I would imagine on any ISP the effect will be far more noticable at FTTC speeds than at ADSLx ones.

That's interesting info though. Maybe BT FTTC won't compare as badly with others as its ADSLx products do. But it's early days. They may just have geared up quicker and the crunch is yet to come, whereas smaller players may gradually improve.

Oh - the random fact . "I can't believe i have lost 10dB snrm". Uhhh? Where does that come from?

That means..... If DLM has not raised my target SNRM to 15dB or more.... and its still at 6dB. I take its that the only other reason i would be synching lower..... but then again am I synching lower or is it just my profile???? as we can't tell as we cant access the modem stats....grrrrrrrr lol

In reply to a post by Trolltamer:

That means..... If DLM has not raised my target SNRM to 15dB or more.... and its still at 6dB. I take its that the only other reason i would be synching lower..... but then again am I synching lower or is it just my profile???? as we can't tell as we cant access the modem stats....grrrrrrrr lol

Quite .

It could be the FTTC DLM is working with banded profiles(syncs), seeing as the whole thing is rate limited anyway.

But anyway, you said both lines started at 16dB SNRM? One typo perhaps, but two? Or did you copy/paste the line and edit the start?

Nope both lines started with 16dB SNRM in fact Line one had 16.9!! So by the graph floating about on here i should be good for 80-90mbps when they "max" it....hence why i'm so miffed that i can't get the max sync back! @ 40mbps..... sorry profile back at 38717.....lol

??
I'm puzzled.

Both started at 16dB, but now you are worried it has risen from the original 6dB to 15dB. "That means..... If DLM has not raised my target SNRM to 15dB or more.... and its still at 6dB.".

Either I'm missing something or you haven't posted something. You are directly contradicting yourself. They can't have started at 16dB and now risen to 15dB. And it couldn't still be at 6dB if it never was 6dB.

But you seem to have gone back to maximum profile so that's good .

Sorry i meant the "target" SNRM had risen to 15dB not the actual SNRM

Just an update really..... ISP (IDnet) 5 weeks in for this problem........ Wants me to send them 2 speed tests.... them and BT Infinity...... what this has to do with resetting dlm/SNRM target i have NO idea!!! And for the record BT's Service has taken a nose dive....... I take it all back tonight .....i'm seeing less than 10mbps now ....... no doubt it will get worse...... Why do ISP's think its OK to sell a product and then deliver something totally different?????? Last night both ISP's were delivering less than 6mbps just after midnight!!!! and there was me thinking a minimum of 12 mbps was TRUE.... If you are with BE/o2 or Sky/Easynet and you get over 10mbps......stay with them....FTTC as you can probably imagine is as good as any BT product......... need i say more?? lol

This is probabvly a really silly question....but here goes...

FTTC is only fibre to the cabinet, so...is your phone line noisy in any way ? From the Cabinet to the premises, infinity and speech run on the same copper pair !

In reply to a post by Trolltamer:

Last night both ISP's were delivering less than 6mbps just after midnight!!!!

That's not unusual. FTTC seems a lot more sensitive to congestion than ADSL (BT skimping on the backhaul is my guess) and at midnight all the off-peak periods kick in.

FTTC seems a lot more sensitive to congestion than ADSL

the target minimum from the cabinet is 20M or VDSL sync which ever lower, what happens after that will depend on ISP and BT backhaul.

MaxDSL product spec said that a service over 2M would perform the same as a 2M fixed speed service under congestion, is there a similar statement for WBC FTTC ? That did mean that a 6M service had to slow down a lot more than 2M in order to get tot he same point.

If statistical contention is based on IP address you still only have one of them so no more horses in the race than an ADSL customer.

In reply to a post by yarwell:

is there a similar statement for WBC FTTC ?

I've no idea, I'm just commenting on what I see here (and others have reported on their lines).

During busy periods, on ADSL2+ my speed would drop by perhaps 25%, on FTTC drops of 60% aren't uncommon.

It's still faster than my ADSL2+ was so not really much of a problem- I just try to avoid the worst of the busy periods

Not a silly question at all!!!

As my ISP couldn't tell me the line stats(or wouldn't) I brought a VDSL2 Modem/Router..... and you are right! I have lost over10dB of SNRM. I did an online phone check and it has come back with a fault (nearly a week later and no response from BT!!) but i'll let you know if that cures it!

Thanks,

Dave

So very random... could it be... my oh my.... MOTHER?! Is that you again!?

Put Flirbles down and don't eat the monitor agaIn either - Mr.Hitachi wasn't in the Karate Kid, and no, he taught you NOTHING!!!!! Ok, stop. Put the apron down coz Mr.Mayagi doesn't teach how to defend yourself with an egg noodle!!

Trollpidgeon, you onl y wan t nead to fire the first guy!