Seemingly capped at 40/10

I have an exchange only BT so called "Infinity 1" VDSL2 service with a dream installation i.e. new property install 3 years ago, no extension wiring, BT NTE5a with MK3 filter, ZyXEL VMG8924-B10A router.

I have confirmed that our DLM profile was reset at last contract renewal - we have only had BT as ISP.

We have a Huawei DSLAM in the FTTC in our rural exchange car park (I assume BT are planning sell this exchange in the future).

During out last contract renewal (£5/mo for unlimited Infinity 1) the BT rep' was proud to announce that our "service would now be up to 55mbps". As can be seen from below the Downlink appears capped at 40mbps.

Any advice how to achieve the full throughput for our circuit would be greatly appreciated.

Router stats are below.

====================================================================================
VDSL Training Status: Showtime
Mode: VDSL2 Annex B
VDSL Profile: Profile 17a
G.Vector: Disable
Traffic Type: PTM Mode
Link Uptime: 12 days: 8 hours: 6 minutes
====================================================================================
VDSL Port Details Upstream Downstream
Line Rate: 4.346 Mbps 39.998 Mbps
Actual Net Data Rate: 4.318 Mbps 39.999 Mbps
Trellis Coding: ON ON
SNR Margin: 5.8 dB 10.4 dB
Actual Delay: 0 ms 0 ms
Transmit Power: - 3.6 dBm 13.1 dBm
Receive Power: -22.0 dBm -9.6 dBm
Actual INP: 0.0 symbols 48.0 symbols
Total Attenuation: 0.0 dB 23.7 dB
Attainable Net Data Rate: 4.258 Mbps 49.782 Mbps
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 7.3 38.9 N/A N/A N/A 18.6 48.9 75.0
Signal Attenuation(dB): 7.3 38.8 N/A N/A N/A 21.0 48.5 78.6
SNR Margin(dB): 5.7 5.8 N/A N/A N/A 10.4 10.4 10.5
TX Power(dBm): -14.8 -4.0 N/A N/A N/A 11.3 7.8 -1.6

Get BT to put you on a 55m profile. Your attainable is 49.

Is it that easy?

It seems too reasonable, all too often I speak with BT rep's and get a "computer says no" response!

If that is the case, I'll try to speak with a UK call centre on Monday.

Don't forget to have the exact figures to hand to tell them:-

Line Rate: 4.346 Mbps 39.998 Mbps
SNR Margin: 5.8 dB 10.4 dB
Attainable Net Data Rate: 49.782 Mbps

The downstream SNR Margin is important. It shows the line is being held back, to the extent shown by the Attainable Rate.

Edited by RobertoS (Sat 20-May-17 22:55:02)

Have you resynched the router since renewal?

Good point.

Don't worry I shall have.

Disappointingly though historically they have not known what I am talking about, they just read from a script and run line tests.

Sorry, yes.

Renewal was in December 2016, with HH5a (27mbps downstream).

I changed this to SmartHub (type A) which gave an improvement (33mbps downstream) due to more compatible Huawei DSLAM SoC.

Two months ago I changed again to ZyXEL VMG8924-B10A (latest stock firmware) with Broadcom 63168 SoC. This improved to 37mbps downstream, then when DLM had stabilised capped at ~40mbps.

In reply to a post by DeanWade:

Is it that easy?

It seems too reasonable, all too often I speak with BT rep's and get a "computer says no" response!

If that is the case, I'll try to speak with a UK call centre on Monday.

I can't advise on BT. My only involvement with BT is the phone line and have had trouble getting an Engineer out to repair a crackly line. Although once I had no dial tone and sent an email when my Mum was alive about her having a dicky heart and no emergency phone line and they sent an engineer on a Saturday morning and it was sorted straight away.

Its best to try and deal with a British call centre but tricky to get in touch with one, the best time is normal during the week daytime to call up and if you can try and get a direct number to a UK call centre.

Then it could be an Openreach DLM "banding" cap.

To check, run the BT Wholesale Performance Test. (Ignore all the red instructions, just say you've done them. We don't need to know these results).

At the bottom of the initial results page click Further Diagnostics. Put your landline phone number in when asked. When it comes up with the graphs and text boxes, what is the IP Profile speed?

If it is very close to 38.71 or 38.67 then it is not banded.

If it is more like 36.anything then it is banded and you really will have a CS problem. let us know what it shows and we can advise further.

Edited by RobertoS (Sun 21-May-17 00:10:40)

On a different circuit we had a crackly line. It was so bad we switched to VoIP.

This was a good move because we only use VoIP now, better dynamic range, no nuisance calls, noise free, more features, inclusive international calls and cheaper than BTs anytime service!

The fault was eventually fixed. The BT Engineer said there was a large impedance imbalance on the "E" line (between the Exchange and PCP).
He resolved the problem by moving us to a new 300 pair multicore that have been run between the exchange and PCP. It also has a totally different riser in the Exchange apparently.

I can thoroughly recommend VoIPtalk.org . I have been with them since 2004. We have their VoIPtalk 1000 service.
FTAOD We have no commercial interest with them.

Thanks for that, always good to know what jargon to use when trying to communicate with BT!

I'll respond to this after I've called BT

I've not been too concerned with resolving this as BT have apparently been planning to experiment with lower SNR margin thresholds this "spring". As is historically the case with these BT statements, nothing has happened.

See my edit.

In reply to a post by DeanWade:

I've not been too concerned with resolving this as BT have apparently been planning to experiment with lower SNR margin thresholds this "spring". As is historically the case with these BT statements, nothing has happened.

The lower sync-time margins will not be applied to banded lines. Also although the original trials have been expanded in scope it is rumoured the expected national rollout has been postponed to September, with the expanded area trial being more like a pilot.

Edited by RobertoS (Sun 21-May-17 00:15:14)

I had a problem on the E side which took about 6 weeks to be resolved. I ended up contacting the BT CEO Office to try and speed up the process. I don't know what was wrong, one minute everything fine next morning no broadband or phone and I saw BT rolling out new E side cables a few weeks later, probably the cables got nicked. I got compensation though from CEO Office.

Is there a list of the banding rates anywhere I have always wondered about this I think I read somewhere, maybe Kitz such a list exists somewhere?

If you could find the banding rate around the 40m mark you would be able to determine if it's banded or capped at 40. Looks like capped to me.

I stumbled across this not so long back, scroll down for the bands.

Edited by IanBB (Sun 21-May-17 01:16:15)

Unfortunately the line is at the 40/10 speed. My way works, because capping seems to cause a discrepancy between the sync reported by the modem and the sync used by BT Wholesale to calculate the IP Profile. The lower (by a few Mbps) BTW speed being what the ISP is passed at their Radius Server.

Thanks for that Ian. So according to that it could be banded or capped there is no real way of telling if say, for instance, DLM has him on a 20-40 band or is indeed Capped at his original 40/10 package. Depending on which it is will affect which way BT proceed either engineer to reset DLM or remotely removing the cap.

That's badly out of date Ian. I've had 60, 55, 49, 45 and 35 IIRC. I can check tomorrow (oops later today) as they are recorded in my sigs and i know roughly when the changes happened.

Banding might show the same lower IP profile if on 20-40m banding.

I've told you twice in the last few minutes Tim. The IP Profile will tell us as it will be well below what is expected from the sync reported by the modem. This has been seen with many users, and in my case i was also able to see the exact figures BTW were using (in bps not even Kbps never mind Mbps), as AAISP give users access to the Radius server reports showing the speed that BTW Is using to set the IP Profile.

Ok Dad.

In reply to a post by Banger:

Banding might show the same lower IP profile if on 20-40m banding.

In my post i gave the poster two figures for the IP Profile calculated from the 39998 sync. The higher one is for no G.INP, the lower is if G.INP is active.

If the IP Profile is well below those then the line is banded.

LOL

Thank's for that.

I'm not at the property at the moment but when I am I shall certainly do the test and let you know how I get on.

Edited by deleted (Sun 21-May-17 08:14:28)

Sorry, what is

CS

?

Customer Service.

I used to email [email protected] but got ignored re' my last issue... so I escalated to [email protected].

As his bonus KPIs are highly reliant on reducing complaints he is motivated to address, which his [executive level complaints] team did to their credit. The Openreach Eng. was the most thorough I have seen.

CS is often shorthand for Customer Service.

The problem is that your CP cannot perform a DLM reset, Openreach are the people who can do that.

Mornin' Bob,

You beat me, I stopped mid reply to slurp tea.

Agreed, and we don't know it is banded. All I originally said was it is a possibility that we need to check.

If it isn't then we can forget about it, if it is then first level CS are unlikely even to know what he is talking about. In fact could waste time as we have seen two or three cases in the last few months where they appear to have triggered a BTW ADSL reset, sometimes more than once for the same customer when it has had no effect.

The first-line or even second line CS at many ISPs could well be completely unaware there are two different DLMs in play on FTTC, with the Openreach one the one that sets the connection parameters. All the BTW one does is set, and operate, the IP Profile. (As you know of course, but some readers in the future may not).

I suppose it's well below to replicate the problems on ADSL when there was line instability but not enough to affect the data rate's or SNR margin's.

...and that is the hardest thing to achieve. Openreach will not resolve if one is above the minimum service provision -10%.

Previously on another circuit I had to resort to reinstalling an old HH5a, reconnecting the property extension wiring and using a plugin filter to get the service below the minimum service provision for Openreach to accept the fault, then when receiving the call from the Eng. before he attended reverse it.

With Openreach being split off I can only see contractual standoffs becoming more common.

What a mess!

Edited by deleted (Sun 21-May-17 09:08:44)

I don't really understand what you are saying there but can be 99% sure it's nothing to do with that. What is known is that when and only when Openreach DLM banding is active then the BTW system is not using the same sync figure as we see our modem report.

Whether this is the Openreach one telling the BTW one a lower figure, or the BTW one is reducing it for some reason, we don't know. I have no idea or theory to explain it.

I'd rather we didn't discuss how and why it happens in this thread as doing so would be a complete distraction from solving the OP's problem.

I'm not saying VDSL is the same as ADSL, I'm just saying that on ADSL when there was line instability, the IP profile was lowered even if the sync rate remained the same. This seems to have been applied to VDSL, too.

Edited by deleted (Sun 21-May-17 09:14:04)

Just a thought, and please don't take it the wrong way .

From the number of lines discussed on these forums FTTC banding is quite a rare occurrence. If you have experienced it at two properties it does make me wonder if either there is something you are doing or an electrical item of some sort or other you possess that is upsetting Openreach DLM.

Tracing such an item can be difficult. It could even in the old days of just ADSL have been faulty "suppressors" in your car's or motorbike's ignition system. Or one that passed by frequently. See here. It was in fact mainly pre-internet and just ruined AM radio or television reception. But! Who knows?

As for what you may be doing, frequent turning Off and on of the modem or modem/router, frequent manually triggered re-sync's when trying to optimise the connection speed, things like that can make the system think there is instability.

There isn't a high probabilty of it being something you are doing, but perhaps it needs to be considered.

Start a thread somewhere if it bothers you. Please don't disrupt this one. Think back, .

Edit: From that explanation I think you are wrong anyway. But shhhhush here.

Edited by RobertoS (Sun 21-May-17 09:34:48)

I'm not wrong at all! There are several threads on the BTCare Community Forum of users complaining about stuck IP Profiles. Please don't try and get me to start a new thread when this needs explaining. Telling some one that they're wrong is a big no no! Maybe think about what you're going to post before you post it.

Edited by deleted (Sun 21-May-17 09:54:50)

The banding issue is only at one property.

All installations [and I have so far corrected >9] are "text book". i.e. NTE5a & Mk3/Mk4, Broadcom SoC routers for Huawei DSLAMS and no extension wiring connected.

Start a different thread as has been suggested

No one has mentioned the unusually low upstream speed, what are peoples thoughts on a line that is skewing the usual balance?

With DLMs logic being undisclosed and what seems dynamic I thought it could be caused by the cap.

My plan was/is to get the downlink cap lifted first then address the uplink if the issue persists.

Well at that attenuation it looks more to me like the downstream is a tad high ?

Looks like a line fault affecting the upstream as the power is way down and only 2 upstream bands are in use

Downstream seems reasonable in comparison with other lines with similar attenuation on MDWS

Ah, OK Dean . I misunderstood this post to include meaning reverse/remove banding, as the context was Openreach DLM resetting.

My apologies.

Post deleted by MrSaffron

Edited by deleted (Sun 21-May-17 11:46:35)

Crikey, you apparently got something wrong for once!

In reply to a post by DeanWade:

With DLMs logic being undisclosed and what seems dynamic I thought it could be caused by the cap.

My plan was/is to get the downlink cap lifted first then address the uplink if the issue persists.

You have a very good speed based on the attenuation. DLM should with time adjust if the line can handle it (we're talking like 4 weeks+ time wise).

In my view getting the ISP to reset DLM is quite pointless, as whatever made DLM apply the speed cap initially is probably still there, so it will just re-cap. If the line truly is fine, DLM with time will adjust. I am by no means saying it does that quickly, often between 2 weeks and 3 months.

No, banding no longer removes itself on VDSL2.

Downstream seems reasonable in comparison with other lines with similar attenuation on MDWS

OK BB, you know me, I like to have a rough idea of the D-side length and be looking at the stats on my tester, and then it's more a matter of 'feel'. Maybe not the scientific approach others might eschew, but it seems to get me by in the main

And flying off the handle and using foul language results in one result a post is deleted

You know the rules and you are not excused from the basic rule set

I know that, just trying to help.

In reply to a post by WilliamGrimsley:

No, banding no longer removes itself on VDSL2.

That is incorrect. My line was banded for a long time - months - but it eventually removed itself.

In reply to a post by WilliamGrimsley:

No, banding no longer removes itself on VDSL2.

It absolutely does.

What people don't get to see is that even if a line is stable on a banded profile it may still fall into DLM's amber category, which would mean DLM wouldn't release or relax the banding.

Thanks for that lee. It makes sense of the inconsistency we see given the limited information we can glean from many modems' stats.

I've had this router in place for >4 months now. I think you are being too charitable to BT/Openreach.

>4 months and a cap is a long while to wait. ES on the line is also very low.

I consider the cause to be BTs complacency rather than something the "magical" DLM is doing and that BT should demonstrate the reason for the cap' and possibly relatively low uplink sync' rate.

Which modem are you using? Ah yes I see it's a ZyXEL VMG8924-B10A. Have you tried another modem?

Edited by deleted (Sun 21-May-17 15:20:46)

Indeed, stats raw stats aren't that helpful as DLM looks at every aspect of the line before it categorises (green amber red, which I'm sure you know).

Most of the posts on Kitz where banding has been relaxed is on lines that MDWS shows green consistently.

As far as I know, once on a banded profile, a line will never be on a fully open 0.128-80mbps unless a full DLM reset is actioned by an engineer.

I don't have a list of the banded profiles as they seem to have changed in the last few years. Sub 40meg bands have increased in number, so the banding isn't as restrictive as it used to be. Most bands lower down seem to be in 1-3meg increments.

Yes, I know most of that, but not all, so thanks for this also.

IIRC WWWombat did not very long ago post the figures DLM uses for its classification system, but I forgot to bookmark it .

In reply to a post by WilliamGrimsley:

No, banding no longer removes itself on VDSL2.

How sure are you? I had a master relocated a month ago, the engineer did a real nasty job. He took the incoming cable, jelly crimped in the original master and a new cable going from here to the new master. As he did his work he kept the original master connected, with my router plugged in.

I made the engineer cut out the original master, and the jelly crimps. & got him to do a direct connection to the new master.

At the end my router had banded (well my sync was stuck lower than usual), it did resolve itself within a couple of weeks.

In reply to a post by lee111s:

What people don't get to see is that even if a line is stable on a banded profile it may still fall into DLM's amber category, which would mean DLM wouldn't release or relax the banding.

Last year, we were getting cases where banding wouldn't relent, even with zero ES. And cases where banding would relent for a few steps, and then stop, even with zero ES.

Is DLM's amber category possible with zero ES?

Having said that, stuck banding was much more prevalent last year. Perhaps things have improved this year.

Agreed.

At best, all we have is guess work really. I doubt the true inner workings of DLM will ever come out.

I have an unusually low upstream compared to my downstream, currently around 47/6. I got quite a bit more downstream with my ZyXel but at the cost of the upstream. Switching back to the hg612 increased my upstream at the cost of my downstream.

The upstream was originally 12, but has been steadily dropping over the years.

I'm in the same boat as you, banded at 60/20 due to a HG612 modem that kept locking up / rebooting.

Just going to leave the line up and see if / what DLM does.

It's been up for 12 days so far.