line Statistics graphs

Hi,

I have just unlocked the HG612 modem as I am having issues with slow throughput speeds in the evenings and was wondering if anyone on here could please take a look at the line stats from program HG612 Settings Editor to see if any issues are showing up there?


could someone let me know,

many thanks

You may want to post a link to the stats/graphs, then people can take a look

If it's only in the evening it could be network congestion, perhaps set up a ping monitor, although you do ideally need a static IP.

Edited by R0NSKI (Fri 31-May-13 17:44:28)

Hi,

Thanks for your response,

I have attached some line graphs, and would be grateful if you or another member could take a look?

http://tinypic.com/view.php?pic=ao5dsw&s=5

http://tinypic.com/view.php?pic=2u4sv0h&s=5



Many thanks,

Edited by deleted (Fri 31-May-13 17:54:26)

The actual data rates (ACTNDR) are excellent: 80MBps down 20Mbps up, so you've topped out!
The max attainable rate (ATTNDR) is 92Mbps/26Mbps which again is excellent.
Attenuation on the top downstream band is 39dB, so you must be within the first few hundred metres of the cabinet.
As for your throughput issue, it appears to be caused by a problem other than the HG612 modem.
Maybe run a pppoe client on the PC itself to eliminate the router (some version of BT Home Hub?) as the cause.
Hope you get it sorted soon because you've got a very good VDSL2 service there.

cheers, a

Beautiful looking graphs and numbers there.

You have a full 80/20 sync, with capacity for higher. There is no FEC or interleaving.

The 18 errors (OHFErr) in 1.3 million frames (OHF) isn't that high - I think that means the modem has been on for around 30 minutes, so 30-40 errors per hour is pretty low (my line currently runs at around 100 per hour, but has been fine at nearer 1000 per hour)

There is no reason for a slow down there.

I'd start next by running a monitor 24/7, to see what the wider network is doing (including your ISP). The TBB BQM (broadband quality meter, or ping meter) is a good tool to try, if you have a static IP.

Who is the ISP ?

Hi.
Thanks for the responses,

Attached is the latest line graph I have and also the stats from the modem, the connection has been up for around 3 hours now.

http://tinypic.com/view.php?pic=dnd1lv&s=5

http://tinypic.com/view.php?pic=2w527vm&s=5

http://tinypic.com/view.php?pic=2w1wkl4&s=5

I will look into getting a static IP address, also am I correct in assuming that if the SNR margin was lowered for the downstream then my speeds could go higher? Or is this still dependent on what the IP profile is set to?

Edited by deleted (Fri 31-May-13 21:47:17)

Your connection is in sync at the full 80/20, with some spare SNRM margin, so as mentioned above you could be experiencing evening network congestion.

Your IP Profile should be around 96.79% of sync speed i.e. around 77.43 Mbps.

What is reported from the further diagnostics here:-

http://speedtest.btwholesale.com/





Are you connecting wirelessly or wired to the router/hub?



Who is your ISP?



What speeds do you see at various times of day from here:-

http://www.speedtest.net/



While your connection is achieving the capped 80/20 sync speeds, lowering the DS SNRM would have no effect whatsoever on throughput speeds.

In reply to a post by snowy44:

Attached is the latest line graph I have and also the stats from the modem, the connection has been up for around 3 hours now.

Yup - still no problem with the line. The error rate picked up a little in the last image, but still isn't a problem.

am I correct in assuming that if the SNR margin was lowered for the downstream then my speeds could go higher?

If the speed wasn't capped at 80, the modem would try to sync at a higher speed, and target 6dB. That target SNRM doesn't ever change in FTTC - DLM works in a different way here.

If you look closely, the text part of the images you have shown indicate an attainable speed of 92Mbps. This is usually a slight over-estimate when interleaving is turned off (and a large over-estimate when it is turned on), so you'd probably be able to get around 90Mbps.

Or is this still dependent on what the IP profile is set to?

The other way around - the IP Profile value (at BT) is set once the sync speed is known.

so you feel good.

your attenuation is very slightly higher than mine, but your attainable downstream is about 23mbit higher than mine.

Your problems I dont think are related to the sync especially as its primary at peak times. Looks more likely to be congestion.

In reply to a post by WWWombat:

Beautiful looking graphs and numbers there.

Is it normal to have that bizarre-looking rolloff in S/N ratio and bits/carrier between 1 and 2MHz?

I see the same on my line and it wasn't there using ADSL2

If it's normal, does anyone have an explanation about what causes it? As a RF-tech that kind of frequency response makes me distinctly twitchy.

Yes, if the effect you mentioned is what I think it is, compare to my graph at http://81.138.100.210/images/2013-6-5/bit_tones/bit_... then yes it's normal. It's to try and minimise the impact of VDSL2 crosstalk for ADSL2+ users.

Edited by Ixel (Wed 05-Jun-13 19:23:06)

Thanks. That makes sense. If only BTOR could provide this information when asked..

It looked like some kind of unterminated spur about 90 metres long on the line, which was making me twitchy.

Peripherally related: With a 12db SNR line syncing at 80/20 would you expect 30-50 uncorrectable DSL errors per hour? (It was a LOT worse on ADSL2 - upwards of 200/hour with 6dB SNR and syncing at 16.5/1)

That notch in SNR (and bit-loading) is the result of downstream PSD shaping.
This shaping is performed to preserve, as Ixel has said, the ADSL connections served by exchange DSLAM kit.
The Profile 17a VDSL2 class mask used by BT to define that shaping is ADE17-M2x-A (short name: B8-11). See page 21 of BT SIN 498 (Issue 4.3) [1]
The PSD mask itself is defined in ITU-T VDSL2 Recommendations G993.2. See page 306 of the 12/2011 Recommendations at [2].

cheers, a

[1] http://www.sinet.bt.com/498v4p3.pdf
[2] http://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-R...

Edited by deleted (Wed 05-Jun-13 19:54:02)

Thanks. That makes sense. If only BTOR could provide this information when asked..

It's actually a branch of Ofcom known as NICC that set the standards for connecting to Openreach's network - the "ANFP".

The PSD has that notch somewhere between 200kHz and 2.1MHz - the location actually depends on the distance that the cab is from the exchange.

You can find the ANFP at the NICC Standards website. Page 30 shows the 6 different PSDs that apply in the UK.

There is also an old VDSL2 primer from Openreach, that dates back to the beginnings of the trial (so only uses up to 7MHz rather than the current 17MHz).

It looked like some kind of unterminated spur about 90 metres long on the line, which was making me twitchy.

If that were the case, you'd presumably see something in the HLog or QLN graphs as well as the SNR graph.

With a 12db SNR line syncing at 80/20 would you expect 30-50 uncorrectable DSL errors per hour? (It was a LOT worse on ADSL2 - upwards of 200/hour with 6dB SNR and syncing at 16.5/1)

The error rate isn't always dependent on the SNR that you are seeing - it really depends on your local environment and the noise seen there. One factor is the crosstalk seen from your neighbouring lines in the cable, so the situation changes as more people take up FTTC services.

My current line runs at 80/20 with about 5dB of SNRM at the moment. There is no FEC or interleaving turned on, so all errors are seen as "OHFErr" counts, rather than "RSUncorr".

It gets around 50-150 OHFErr errors per hour.

This time last year, when there was more leeway, and it ran about 7dB, it ran at between 400 and 1000 OHFErr per hour. There was a step change in error rate sometime between September and November that I didn't catch in my statistics.

Ye Gods! I forgot all about the ANFP complicating things even further! Possibly if you studied the SNR profile closely enough you could maybe work out which of the six downstream PSD masks is being utilised?

cheers, a

Oh yes.

The troughs would be at
- CAL 50 = 450 kHz
- CAL 40 = 600 - 800 kHz
- CAL 30 = 1.1 - 1.2 MHz
- CAL 20 = 1.8 - 2.0MHz
- CAL 10 = 2.2 MHz (but not as deep as the previous troughs)
- CAL 0 = No trough (flat from 200kHz to 3MHz)

I've not seen a graph for CAL-0 though. I guess you need to be on a cabinet outside the exchange for that one.

On my old line, the trough was around tone 410-480, or 1.7-2.0 MHz. That'd be "CAL 20". The cabinet on that line was about 1.2km from the exchange building, following the obvious road.

On my current line, the trough is at tone 300, or about 1.2MHz. I guess that is the "CAL 30" mask. This cabinet is definitely further from the exchange, but I don't know the distance. Probably about 1.5-1.6km.

Hi,
Thanks for the responses,

My ISP is BT, I have done a speedtest at this link: http://speedtest.btwholesale.com/ and it confirms that my IP profile is 77.43 Mbps.

As this looks like a congestion issue with the network would moving to an alternative provider resolve this issue? Or do all IPS's route through the same BT equipment?

The connection the router is wired and all speedtests are being done wired as well.

Edited by deleted (Thu 06-Jun-13 08:43:31)

the Committed Information Rate on the cabinet to exchange link from Openreach is 30 Mbits/s if you're on 80/20 product. So there's one potential bottleneck. That would apply to any FTTC using Openreach cabs, inc Talk Talk and Sky.

After that it's the BT Wholesale network vs either TT or Sky.

I can't recall what BT Wholesale's ambitions for minimum service are - something like 12M minimum at the busiest 3 hour period ?

For End-User Accesses selecting the "Standard" traffic option, BT Wholesale will
provide a throughput level of at least 12 Mbit/s for 90% of the busy 3 hour period.

For End-User Accesses selecting the "Elevated" traffic option, BT Wholesale will
provide a throughput level of at least 16Mbit/s for 90% of the busy 3 hour period.

Edited by yarwell (Thu 06-Jun-13 08:54:10)

Hi,
Thanks for the responses,

So just to confirm if I did move to an alternative provider this problem would most likely continue as all providers route traffic through the BT network?

Thanks,

All providers use the same link from the exchange to your house.

Talk Talk/Sky use there own back haul from the exchange to their network, others use the BT back haul.

How long is a piece of string?

I guess, on average, that any repeatable congestion doesn't come from BT's core network, nor from their pool of connections between the core and their ISP equipment. If it did, every BT user would be reporting the same kind of problem.

If it happens to you regularly, then it suggests something closer to your particular exchange or your particular cabinet - in which case swapping to a new ISP may not have an effect.

If it happens every day, with repeatable restrictions, it is probably personal - perhaps something set on your account.

It may be best if you take this problem over to BT direct, rather than have us answer generically. I think BT-Care staff look in on the BT forum here (they have an ID, but don't post that much), or you can look at their own community website (see the "help" link contained in the profile of the ID I just linked to).

But do let us know how it goes.

Hi there,

Thanks for the response,

Unfortunately this issue dosnt seem to be progressing much further from when I last posted on this thread. BT said that they would request for a lift and shift to be done on my local cab to see if this resolved the issue but they are saying now that as the line keeps passing tests that they are not going to do this. I just wondered if anyone on here could advise if there is any other options that I could get BT to look into? The speeds are now dropping to the low 20's during peak times.

Thanks for your help.

Hi,

Just wondering if someone could please assist further with this issue?

Thanks in advance.

You best bet is to contact the BT forum mod at: http://bt.custhelp.com/app/contact_email/c/4951 . But be aware they take 3 working days to reply: sometimes more if busy; but they have a good record of getting things solved once they are on the case. You will probably need to post on the BT forum as well to give a cross-link to the request.

Hi,

Thanks for the response,

I have just taken a look at the line stats on the BT Modem and notice that there are quite a lot of CRC errors. The connection has only been up for 2 days. Is this normal or could be a problem on the line?

http://tinypic.com/view.php?pic=2l9ktps&s=5

Edited by deleted (Fri 05-Jul-13 19:16:26)

The modem's GUI misreports FEC & CRC errors.

You need to compare data from xdslcmd info --stats & xcdslcmd info --pbParams over a period of time or set up a monitoring program such as this one:-

HG612 Modem Stats 1.0

It does look like DLM has taken some action already & lowered your DS sync speed to below 80 Mbps.

Hi,

I just wanted to update this thread.

The issue is still ongoing BT are now saying that even though the SVLAN is not working to full capability they do not believe that this is the cause of the issue. They are now saying that all XDSL services will be slow during the evenings, I fully understand that but I feel that a 40Mb drop is quite excessive. Basically this issue is not going anywhere and I was wondering if anyone on here has had any experiences with this problem in the past if so were they able to get BT to resolve it?

Post deleted by MrSaffron

Are you using the home hub?

Post deleted by MrSaffron

Ok, if you are experiencing congestion then a different provider may work. However if you go with sky you may not be able to use that router directly. You should be ok with it on talktalk though.

If you went with AAISP they may be able to throw some light on what's happening.

Post deleted by MrSaffron

You would stay on the same cabinet, no idea about the other bit.

Also with sky you would not be able to use your own router, as Sky will not tell you the login details, although it is apparently possible to extract them from the sky router.

In reply to a post by R0NSKI:

Also with sky you would not be able to use your own router, as Sky will not tell you the login details, although it is apparently possible to extract them from the sky router.

You also need a router that does the unusual DHCP, the majority do not work.

Post deleted by MrSaffron

Post deleted by MrSaffron

Edited by deleted (Fri 30-Aug-13 22:02:32)

I couldn't find any previous stats, only a screen shot of the modem.

But things do indeed look better, you now have attainable speeds of 93072kbps DS, compared to a previous of 91872kbps

But the upstream has changed a lot more, you now have 31296kbps, compared to previous of 26602kbps.

Of course these are only theoretical attainable speeds and you are synced at the maximum of 79999/20000 on fast path.

I can't tell you any more than that.

What you worried about you've got the best speeds you can currently get on FTTC?

Post deleted by MrSaffron

Those graphs are not going to help with diagnosing speed drops in the evening, the daily graphs (ongoing_stats) might show a bit more info, but ideally you should set up a ping monitor, you'll need a static IP for this, or need to update it each time it changes, which is not recommended.

The most likely cause is congestion somewhere in the network.