Live opposite the exchange yet only get 12Mbps

Since I moved to a flat that's quite literally next to the exchange I figured that I'd get pretty decent ADSL2 speeds, yet the best I seem to be able to achieve is around 12Mbps (BT checker) which according to CS is just fine. Is this right, or has something gotten a bit messed up?

BT results:

Download speed achieved during the test was - 12.74 Mbps
For your connection, the acceptable range of speeds is 4 Mbps-21 Mbps.
IP Profile for your line is - 13.48 Mbps

Upload speed achieved during the test was - 0.69Mbps
Upstream Rate IP profile on your line is - 0.83 Mbps

Modem stats (Downstream/Upstream):

SNR Margin (0.1 dB): 97 127
Attenuation (0.1 dB): 100 59
Output Power (0.1 dBm): 215 122
Attainable Rate (Kbps): 22224 24107
Rate (Kbps): 15285 828

Mode: ADSL_2plus

SNR is 9.7dB that why u get lower speed. If u are with Plusnet, u can ask Plusnet to get your SNR reset target at 3.0dB to gain more speed.

How long have you had the connection? If it is in the last few days then it may improve automatically.

Otherwise it looks like something is holding back your speeds - asking Plusnet to lower the target SNR may sort it. Can you get the stats immediately after a reboot?

About a week or so, my best guess is that it might have something to do with me having to fight with my modem to get it to work bridged (turns out the trick is to ignore Plusnet's guidance and pick LLC-Based multiplexing) leading to a bunch of disconnections in the first couple of days, but it's been pretty stable since.

Unsure if it's related, but after asking interleaving to be switched off, a Service Notice popped up on my account noting that I'll be moved over to 21CN by midnight tonight, though according to CS it's already happened. Not really sure why it wasn't from the start..

In reply to a post by hopkapi:

a Service Notice popped up on my account noting that I'll be moved over to 21CN by midnight tonight, though according to CS it's already happened.

It has already happened. Otherwise you'd only be getting 8 meg Sync speed.

Your line is good for about the full monty 24 Meg @ 6dB NM. Your current 9dB NM does not account for the 8-9 Meg reduction you are getting, perhaps only 2-3 Meg of it. However wait a days to see if it settles.

Are there any working extensions in the flat ? Have you tried plugging into the test socket behind the lower part of the BTmaster socket, in order to eliminate any internal extension wiring and also the faceplate it's self, ? As said give it a day or so , if no improvement then try the above ,
also have you performed a quiet test using a corded phone 17070 option 2, ?
if there are any noises such as crackling or other noises that are odd present there may be a fault with the line itself

As for your speed, that is currently being restricted by the current Bras IP profile which is set by Bt's woeful DLM Your connection has probably been interleaved which won't help with getting max speeds,
Also the Upstream sync appears to be capped, ask your isp to uncap it , you may get a 1mbps usable upstream rate then ,
If the IP profile doesn't increase then i think the ISP can get it reset , or maybe even disable DLM altogether ,

But IMO getting around 13mbps throughput with a sync of around 14.5-15mbps with a short line, and attenuation figures like yours isn't just fine at all, fine for who the isp?

Edited by tommy45 (Wed 21-May-14 18:19:47)

In reply to a post by ian72:

How long have you had the connection? If it is in the last few days then it may improve automatically.

Unlikely. All variants of xDSL start out at full speed and generally only drop over time.

In reply to a post by tommy45:

As for your speed, that is currently being restricted by the current Bras IP profile which is set by Bt's woeful DLM

Slow down Tommy .

The Bras IP Profile is set by the connection speed, not the other way round. Connection speed (15285kbps) x 0.882 = 13.48Mbps which is the IP Profile displayed.

Nothing at all wrong there. The reason for the low connection speed is what we need to look for. Sort that out and the IP Profile will track it.

The diagnostic tests you suggest might help.

Edit - IIRC the 828kbps upstream might be the maximum on BTW interleaved.

Edited by RobertoS (Wed 21-May-14 23:03:14)

In reply to a post by RobertoS:

Edit - IIRC the 828kbps upstream might be the maximum on BTW interleaved.

Usually, but not always (E7er sometimes had higher but I've never seen it), 888K (or sometimes 444K with half-speed PN ).

Agreed, IPProfile is not a problem or a cause. I just ignored Tommy's fallacious argument .

Edited by XRaySpeX (Thu 22-May-14 00:08:17)

We know when tommy is wrong, but the OP, or a later chance reader, may not . So it had to be refuted.

In reply to a post by RobertoS:

In reply to a post by tommy45:

As for your speed, that is currently being restricted by the current Bras IP profile which is set by Bt's woeful DLM

Slow down Tommy .

The Bras IP Profile is set by the connection speed, not the other way round. Connection speed (15285kbps) x 0.882 = 13.48Mbps which is the IP Profile displayed.

Nothing at all wrong there. The reason for the low connection speed is what we need to look for. Sort that out and the IP Profile will track it.

The diagnostic tests you suggest might help.

Edit - IIRC the 828kbps upstream might be the maximum on BTW interleaved.

And what controls the sync rate, DLM?

And yes i know that the bras IP profile is set based on what the sync is , and i didn't say differently But it still can restrict throughput , should that IP profile get stuck or fail to update correctly(which is a known issue) that it's self can be a reason for low throughput on a high sync, not that i'm saying it is the case here,(just to be clear)

Edited by tommy45 (Thu 22-May-14 01:48:41)

In reply to a post by tommy45:

And what controls the sync rate, DLM?

And yes i know that the bras IP profile is set based on what the sync is , and i didn't say differently

You did, you mixed up the 2:

In reply to a post by tommy45:

As for your speed, that is currently being restricted by the current Bras IP profile which is set by Bt's woeful DLM

which Roberto was clarifying.

Yes, the DLM controls the sync rate by responding to the line conditions which appear to be imperfect.

If DLM sets the sync speed then as a result of that DLM is responsible for the bras profile as well, wether directly or not, How is that mixing the 2 up?,

I have a friend who lives literally 5 metres from the exchange. however, he only gets about 12.5meg. Reason? Instead of turning left as it leaves the exchange, his line goes right, into town, out of town about 1 mile, does a uturn, goes through a huge estate and then finally, after travelling another .75 miles, arrives at his house!

Craziness!!!

For a pure phone service it was probably the easiest and cheapest way to do it as that is probably where the ducts were. They wouldn't have known at the time that line length would become critical to services that didn't exist then.

haha yep very true. He isn't that bothered as he doesn't use the Internet very much.

In normal circumstances the DLM does not set the sync speed. It sets various stability parameters. The same parameters are set by LLU ISPs whether or not they permanently run a DLM or just for an initial period. Similarly in the case of FTTC, the Openreach DLM sets the parameters.

In cases of severe instability the BT Wholesale or Openreach DLM can apply banding. That does restrict the sync speed, but does not set it.

The sync speed is negotiated by the modems at each end, taking into consideration those parameters and more importantly the actual line conditions at the time of connection. That's why on lines that are not capable of running at the maximum speed for the product using them that the sync varies each time a connection is made. The parameters set by the DLM do not change, but the line conditions do.

That's the RAS in BRAS.

You have a rough idea of what you are talking about, but your initial statement about the DLM restricting the speed was misinformation of the kind that creates broadband myths.

Edit - Nor is there much wrong with the current BT Wholesale and Openreach DLMs. Far from "woeful".

Edited by RobertoS (Thu 22-May-14 10:51:30)

In reply to a post by RobertoS:

In normal circumstances the DLM does not set the sync speed. It sets various stability parameters. The same parameters are set by LLU ISPs whether or not they permanently run a DLM or just for an initial period.
Similarly in the case of FTTC, the Openreach DLM sets the parameters In cases of severe instability the BT Wholesale or Openreach DLM can apply banding. That does restrict the sync speed, but does not set it..

What about LLU ISP's that don't run DLM at all, where DLM doesnt exist, ?
Which often results in customers getting a higher sync rates compared to where LLU DLM is used,It can cap the headline speeds too,

In reply to a post by RobertoS:

The sync speed is negotiated by the modems at each end, taking into consideration those parameters and more importantly the actual line conditions at the time of connection. That's why on lines that are not capable of running at the maximum speed for the product using them that the sync varies each time a connection is made. The parameters set by the DLM do not change, but the line conditions do.

That's the RAS in BRAS.
You have a rough idea of what you are talking about, but your initial statement about the DLM restricting the speed was misinformation of the kind that creates broadband myths.

For BTW systems, DLM works differently ,
But the IP profile can restrict throughput, if it fails to detect or get updated as to what the current sync rate is, should that be higher than it previously was, And DLM can & does ramp up the target noise margins, that in turn does lower the sync rate, So if that isn't DLM controlling the sync rate i don't know what is,

In reply to a post by RobertoS:

Edit - Nor is there much wrong with the current BT Wholesale and Openreach DLMs. Far from "woeful".

As for the BTW 21cn /FTTC Openreach DLM not being "woeful" well thats a matter of opinion maybe we should have a poll to see how many are for DLM or against it?

Edited by tommy45 (Thu 22-May-14 13:34:45)

In reply to a post by WelshWArrior:

Instead of turning left as it leaves the exchange, his line goes right, into town, out of town about 1 mile, does a uturn, goes through a huge estate and then finally, after travelling another .75 miles, arrives at his house!

Then that detour will be reflected in his attenuation and he will have a much higher attn. then the 10dB of the OP.

So his circumstances are not relevant to the OP's issue.

I think we can now leave the OP and anyone who comes across the thread in the future to make there own mind up . There's too much wrong or out of date in that post for me to have the will to go over it all again, as most of it has been covered in earlier posts.

Hi hopkapi,

If you can message over your username I'm happy to the a look at your connection to see if I can see anything amiss.

Also, what is your speed estimate?

DLM does not set the sync speed. It sets various stability parameters.

Indeed.

I think Tommy *may* be lumping the IP Profile system in together with the whole DLM statement.

DLM does not set the sync speed. It sets various stability parameters.

Which in turn will decrease or increase the rate that the connection will sync at, hence DLM setting /controlling the sync as well as other parameters of course, And sends this to the bras where it generates the profile according to the sync speed negotiated by dslam and cpe modem
info contained within this thread seems to sugest something similar

The IP profile is in that way connected to DLM, But as far as the end user is concerned the IP profile serves to regulate the actual throughput, and occasionally the system that control this can have a senior moment or two, following a changing in sync if the sync increases but the bras profile remains at the previous value, throughput will be throttled back to its previous level set by the ip profile, until it either updates or is reset manually (if that is possible) if the sync decreases but bras remains at the higher level, no adverse effects regarding throughput would be observed, that's basically my understanding of how it works

Edited by tommy45 (Thu 22-May-14 19:48:46)

Hmmm,

In all that discussion nobody seems to mention the ring wire.

http://www.kitz.co.uk/adsl/socket.htm

Covered by Tommy;s excellent suggestion of using the test socket, which will be a 1st step diagnostic towards looking at the extension wiring.

Indeed.

Well. Two comments Tommy.

First, it's good to see you've been doing some research and are now getting close to what happens. But I don't need you to inform me about it - you will only find stuff that agrees with what I've been telling you.

Second, the link you give happens to be to the pirate copy of these forums. Or didn't you notice that . Maybe you'd like to find it on these and edit the link. Otherwise you increase their visibility on google .

Well it was google that found that link, for me,so i doubt it will make a lot of difference,
And no i ain't been researching how DLM works because TBH i didn't need to,
Original link below
Does a re-synch always result in a lower IP Profile?

Tommy, stop digging yourself deeper into the hole when I've tried to offer you a hand out of it . Taking your latest wriggle:-

hence DLM setting /controlling the sync as well as other parameters of course, And sends this to the bras ...

Wrong. The DLM sets the noise margin; Impulse Noise Protection level and Fast Path/Interleaving. The difference between "setting" and "controlling" is huge. They are far having the same meaning, which is what you imply.

On all connections, including LLU, those same parameters are set by the ISP, be it dynamically or statically. That is not something special to the BT Wholesale DLM.

... where it generates the profile according to the sync speed negotiated by dslam and cpe modem

So we come to the nub of it. You now say "generates the profile according to the sync speed". Directly contradicting:-

In reply to a post by tommy45:

As for your speed, that is currently being restricted by the current Bras IP profile

which is all I did in the first place where the sync speed was being discussed.

In reply to a post by RobertoS:

The Bras IP Profile is set by the connection speed, not the other way round. Connection speed (15285kbps) x 0.882 = 13.48Mbps which is the IP Profile displayed.

Nothing at all wrong there. The reason for the low connection speed is what we need to look for. Sort that out and the IP Profile will track it.

The diagnostic tests you suggest might help.

It appears that I was wise in ignoring it .

Just to update people, nothing, other than my FTTC date dropping from the end of this month to the end of the year (grrrrrrr) has changed, despite an SNR reset having apparently concluded by now. I messaged Chris a couple of times but he couldn't find anything initially and hasn't responded to my subsequent replies. Opened a new ticket (86296837) with broadly the same info but haven't had a response from CS yet.

What do your line stats look like now?

In reply to a post by RobertoS:

What do your line stats look like now?

Pretty much the same as before:

Downstream / Upstream

Line Coding(Trellis): On Off
SNR Margin (0.1 dB): 99 47
Attenuation (0.1 dB): 100 58
Output Power (0.1 dBm): 215 122
Attainable Rate (Kbps): 22220 20794

what is Line Coding(Trellis): On Off mean?

In reply to a post by adslmax:

what is Line Coding(Trellis): On Off mean?

I'm not sure, but since I posted this, CS have responded to my ticket and kicked off another SNR reset that actually seems to have gone through this time, resulting in these stats (and trellis back on for both):

Downstream / Upstream
Line Coding(Trellis): On On
SNR Margin (0.1 dB): 29 56
Attenuation (0.1 dB): 100 58
Output Power (0.1 dBm): 210 122
Attainable Rate (Kbps): 22252 22637

BTW speed test:

Download speed achieved during the test was - 12.91 Mbps
For your connection, the acceptable range of speeds is 4 Mbps-21 Mbps.
IP Profile for your line is - 17.58 Mbps

I'm hoping this is the sort of thing that'l now hopefully just fix itself providing I don't get a bunch of dropouts?

In reply to a post by pcoventry76:

yes - the more stable the line the more the DLM will chill.

like mine stable for 66 days lol

You are now waiting for the Plusnet "Current line speed" to update to just below that IP Profile. It should happen by the morning. Or you could ring them and they can up it immediately. (It does cause a PPP disconnection so don't ask for it if someone is using the connection).

It should be 17.4Mbps I think. Possibly 17.5.

Edited by RobertoS (Thu 29-May-14 22:04:01)

It's rounded down to the nearest 0.1, so 17.5 would be correct.

So, a week or so later with a very stable line, my SNR is back up to what it was before, my speeds are no better, and CS are advising me that all is well because my speeds are within BTW�s estimated range and therefore they won't change the line profile up beyond 14Mb.

Feel a bit like I'm hitting my head against a brick wall here.

"Customer called as he believes he has a speed issue, his line is rated to 16Mbps with a recommendation of approx 14 Mbps He has advised he is getting 13.4Mbps

Advised that there is no issues at all with the speed of the service"

I'm in a rush now, but have had to track back to your opening post to see a "Rate" figure. The "Attainable" is not the main figure to look at. That is not relevant to the IP Profile or actual speed. The "Rate" is what we should be looking at, with the "Attainable" as additional info about the line.

Having said that, things don't look to be as they should be. I'll go through the thread again in more detail laer, but stats including the Rate would be useful in the meantime.

Ask and ye shall receive:

Downstream/Upstream
Line Coding(Trellis): On On
SNR Margin (0.1 dB): 98 119
Attenuation (0.1 dB): 100 59
Output Power (0.1 dBm): 215 122
Attainable Rate (Kbps): 22176 23601
Rate (Kbps): 15285 8280

Your line is currently syncing at 9dB. The DLM does have a target of 3dB, are you able to try a resync to see if this will push your SNR sync margin down?

In reply to a post by chrispurvey:

Your line is currently syncing at 9dB. The DLM does have a target of 3dB, are you able to try a resync to see if this will push your SNR sync margin down?

That was actually right after a resync. It was 3dB for a while but went back up to 9/10 for no apparent reason about a week ago.

In reply to a post by chrispurvey:

Your line is currently syncing at 9dB

OP's line should be capable of 24 Meg @ 6dB. A 3dB or even 6dB decrease in NM does not fully account for the 9 Meg loss of sync speed he is seeing.

So something is causing noise on the line, I'm wondering whether this is the reason your speeds a as they are due to this.

Something is causing your line to error as Interleaving has been turned on. Have you been able to try another micro-filter? We may also need to look at getting a new master socket fitted as you have an older style one.

In reply to a post by chrispurvey:

So something is causing noise on the line, I'm wondering whether this is the reason your speeds a as they are due to this.

Something is causing your line to error as Interleaving has been turned on. Have you been able to try another micro-filter? We may also need to look at getting a new master socket fitted as you have an older style one.

While it'd be good to know whether you've got data showing noise or whether it's just that interleaving got switched back on, I'm certainly happy to help troubleshoot things from my end and can certainly swap the filter over, I also have another router I could try if you'd like to rule that out too.

I updated ticket #86296837 a couple of days ago though I haven't had a response yet, so I'm currently listening to your hold music once again. I'm wondering if there's anything special I should say to not get the same shrug-off I got last time I called.

You may find this http://forum.kitz.co.uk/index.php?topic=12310.0 interesting with regard to very short lines

It would certainly be worth trying another filter and also router to see if there's any difference.

You'd be best to do the above prior to speaking with our support team to be honest, once you've done that let me know if there's any difference.

Remember when trying a new filter and/or router to look for the actual connection speed, not the attainable .

In reply to a post by chrispurvey:

It would certainly be worth trying another filter and also router to see if there's any difference.

After digging out my old Sky router and figuring out how to get around it being locked to them (it initially connected to them quite happily, which surprised me a bit), my stats are looking quite a bit better. My speeds have only improved a tad so far though, and I think interleaving is still probably on.

Downstream / Upstream
Line Coding(Trellis): On On
SNR Margin (1 dB): 3.2 12.4
Attenuation (1 dB): 7.5 4.6
Output Power (1 dBm): 21.2 12.2
Attainable Rate (Kbps): 22808 1440
Rate (Kbps): 19661 828

BTW speed test:

Download speed achieved during the test was - 15.24 Mbps
For your connection, the acceptable range of speeds is 4 Mbps-21 Mbps.
IP Profile for your line is - 17.35 Mbps

Plusnet current line speed:
16 Mb

Is there anything more I need to do, or will it just nudge itself up on its own?

That certainly looks better, I've also just placed a reset on your line and this has removed interleaving and increased your upload and download slightly.

Your downstream is now at 20024kbps and your upstream is 1152kbps.

I've also updated your speed profile to reflect the difference, do you want us to arrange another router to be sent to you?