How Has Crosstalk Affected You?

Given Openreach are hopefully, at some point rolling out vectoring I thought it'd be interesting to see how people are being affected by crosstalk.

Also might help give some indication of the kind of loss people who aren't hitting full rate can expect. I can imagine BDUK enabling a fair amount of longer lines.

Here's Mine:

Only one on cabinet.

150+ lines down.

I have had FTTC for nearly three years and have had no noticeable effect from crosstalk. Apart from the almost inevitable drop in the first few days (for those not very near to a cabinet), my speed has been constant with a sync of just under 70/20 for the whole time, other than a brief period when there was a fault. I have no evidence of what the FTTC take-up has been in the area; I know I was one of the early ones, but I am in a village that previously could only get poor ADSL speeds due to the distance from the exchange in the nearby town. I am roughly 450m from the cabinet.

Edited by kasg (Fri 03-Jan-14 15:20:29)

I will keep it short and sweet to avoid a rant.

2 weeks after I signed up when I unlocked my modem I had 110 max down and 36 max up. (dont know if it was higher before that).
3 weeks after signup I had max 90 down and 36 up.
4 weeks after signup I had max 73 down and approx 29 up.

Since then it has slowly been going down but no more large jumps.
Currently at 66 down and 27 up. I have lost around 40% of the downstream signal, as far as I am aware I was the first on my cabinet.

Currently I sync 6mbit below my new estimate which ironically is higher than my original estimate.

Edited by Chrysalis (Fri 03-Jan-14 15:25:40)

My home is approximately 800m line length from the cabinet; physically 200m from the cabinet but the duct goes along an adjacent road before going into my road and all the way back to my house; so I am the second-to-last house connected. I guess this means I will suffer more from crosstalk than anyone else in the road.

My sync started-off at around 50Mbps, in the past six months it slowly reduced down to 34Mbps. I am hoping that vectoring will increase it to at least 40Mbps.

Distance from cab - 320 metres according to Google Earth.

My initial connection in May 2012 was 79999 down, 20000 up with attainables of 92000 and 36000.

I don't have access to my modem any longer but I'm seeing throughput of 67/18.5.

The recent firmware upgrade gave me a 10% boost on downstream and allowed for the removal of interleaving.

Edited by Andrue (Fri 03-Jan-14 15:54:29)

FYI, you can get your line's current IP profile (approx. 97% of sync) from this site:

http://windows.mouselike.org/be/index.asp?DoAction=B...

It's quicker and easier than using a BT Wholesale speedtest, and you can check it remotely.

In reply to a post by DougM:

FYI, you can get your line's current IP profile (approx. 97% of sync) from this site:

http://windows.mouselike.org/be/index.asp?DoAction=B...

It's quicker and easier than using a BT Wholesale speedtest, and you can check it remotely.

The current Downstream BRAS rate is: 68.7 Mbps
The current Upstream BRAS rate is: 20 Mbps

In reply to a post by DougM:

FYI, you can get your line's current IP profile (approx. 97% of sync) from this site:

http://windows.mouselike.org/be/index.asp?DoAction=B...

That doesn't work for me, and I don't think it has for some time:

Looks like BT refused to test, possibly because a speed test or BRAS check has been run recently which prevents this tool from working. Try again in a few hours.
Debug: BT no BRAS info

Does anyone know if any information about the vectoring trials have been released? I thought they had finished.

In reply to a post by DougM:

It's quicker and easier than using a BT Wholesale speedtest, and you can check it remotely.

it just runs the BT Wholesale speedtest, which can be run remotely anyway

I charted my sync speeds a while ago, by scraping the data from Zen's customer portal and importing into Excel. It goes back around 18 months.

Metadata: Zen Fibre Unlimited, Line approx. 500m to PCP (Purley Exchange cabinet 6).

Here's a screenshot: http://i.imgur.com/sZmL4dc.png

As you can see, there's been a general downward trend from late 2012. Our neighbours had major building works from June-October 2013, and my hypothesis is that the general electrical noise generated by them really impacted the sync during this period. It stabilised in October to around 68Mb, and then by mid-December, lots of people have turned their tacky Christmas lights on...

Whether this general trend (noisy builders aside) is down to crosstalk I can't be sure, but I live in an area in which I imagine Infinity uptake is fairly high.

Edited by deleted (Fri 03-Jan-14 16:31:29)

Virgin Media Cable isn't affect by any general electrical noise nor tacky Christmas lights on. BT had never learn from it for the last 25 years!

In reply to a post by adslmax:

Virgin Media Cable isn't affect by any general electrical noise nor tacky Christmas lights on. BT had never learn from it for the last 25 years!

How is this relevant to the topic? Besides, VM has problems of their own, like chronic congestion on many local network segments.

that's a new one on me. What have you unlocked, the BT modem?. From memory, the BT engineer test equipment said I could get 120M down and 53up. Is it actually possible to unlock something to get the full speed available for the line?

In reply to a post by adslmax:

Virgin Media Cable isn't affect by any general electrical noise nor tacky Christmas lights on. BT had never learn from it for the last 25 years!

Really?

In reply to a post by iand:

that's a new one on me. What have you unlocked, the BT modem?. From memory, the BT engineer test equipment said I could get 120M down and 53up. Is it actually possible to unlock something to get the full speed available for the line?

U cannot get maximum speed as the exchange capped your speed at 80/20 as you won't getting more than that. Pointless to get unlocked BT modem to get 120Meg down and 53Meg up. .

Edited by adslmax (Fri 03-Jan-14 18:18:36)

In reply to a post by adslmax:

In reply to a post by iand:

that's a new one on me. What have you unlocked, the BT modem?. From memory, the BT engineer test equipment said I could get 120M down and 53up. Is it actually possible to unlock something to get the full speed available for the line?

U cannot get maximum speed as the exchange capped your speed at 80/20 as you won't getting more than that. Pointless to get unlocked BT modem to get 120Meg down and 53Meg up. .

we are talking about the affects of crosstalk, so attainable figures are not pointless.

In reply to a post by iand:

that's a new one on me. What have you unlocked, the BT modem?. From memory, the BT engineer test equipment said I could get 120M down and 53up. Is it actually possible to unlock something to get the full speed available for the line?

Yes- if you have the HG612 modem you can unlock it and get the attainable rate.

In reply to a post by DougM:

http://windows.mouselike.org/be/index.asp?DoAction=B...

It's quicker and easier than using a BT Wholesale speedtest, and you can check it remotely.

Warning
BT have changed their systems, this tool now has to actively submit information to BT to read the BRAS details.
This may cause problems if your internet provider needs to use BT Speed Tester results for diagnostics and fault reporting in the near future. If in doubt, do NOT run this tool.

Running this tool will also prevent you from running the BT Java based speed tester for a few hours.

On sky fibre.

Edited by francisuk25 (Fri 03-Jan-14 19:59:35)

In reply to a post by francisuk25:

Warning
BT have changed their systems, this tool now has to actively submit information to BT to read the BRAS details.
This may cause problems if your internet provider needs to use BT Speed Tester results for diagnostics and fault reporting in the near future. If in doubt, do NOT run this tool.

Running this tool will also prevent you from running the BT Java based speed tester for a few hours.

That's the warning it gives to everyone before submitting the number. Incidentally, I just tried it again and this time it worked:

The current Downstream BRAS rate is: 67.37 Mbps
The current Upstream BRAS rate is: 20 Mbps

Edited by kasg (Fri 03-Jan-14 20:19:05)

In reply to a post by DougM:

FYI, you can get your line's current IP profile (approx. 97% of sync) from this site:
http://windows.mouselike.org/be/index.asp?DoAction=B...

Not sure if it works for those who are "LLU", which includes Sky and TalkTalk fibre products.

I'm on BT Infinity 2 and get:

The current Downstream BRAS rate is: 51.1 Mbps
The current Upstream BRAS rate is: 20 Mbps

As I have an unlocked HG612 modem, my sync stats right now are 52893 kbps / 9598 kbps. My theoretical maximum would be 60132 / 9725.

Back in September 2012 after installation I was syncing at 49912 / 12065 and the theoretical max was 59448 / 11957 - so I've seen a drop in upload and an increase in upload. I suspect that's more to do with changes to the HG612 firmware than anything on the line!

( Speedtest on this site shows 48.8 Mbps download and 8.9 Mbps upload:
http://www.thinkbroadband.com/speedtest/results.html... )

Edited by jchamier (Fri 03-Jan-14 20:40:14)

In reply to a post by adslmax:

Virgin Media Cable isn't affect by any general electrical noise nor tacky Christmas lights on. BT had never learn from it for the last 25 years!

Rubbish.

In reply to a post by jchamier:

Not sure if it works for those who are "LLU", which includes Sky and TalkTalk fibre products.

I'm on BT Infinity 2 and get:

The current Downstream BRAS rate is: 51.1 Mbps
The current Upstream BRAS rate is: 20 Mbps

It can't. Sky / TalkTalk don't have an IP Profile to be obtained.

As an aside having a second line installed and enabled for FTTC imminently. Anyone done thing, and how much of a performance hit did you note on the original line?

Just a little more information.

http://www.jdsu.com/productliterature/sda_app_note3_...
https://en.wikipedia.org/wiki/Ingress_(signal_leakag...
http://piedmontscte.org/resources/SCTE+Piedmont$2C+N...
http://www.cascaderange.org/presentations/Return_Pat...

I especially like this part:

Ingress is the most common problem that operators of two-way services are struggling with

Along with this part:

Common Sources of Ingress
 Off Air

� Short Wave Radio (4.75 to 10 MHz)
� Ham Operators (7, 10, 14, 18, 21, 24 & 28 MHz)
� CB Radios (27 MHz)
� Broadband noise (things with electric motors, PCs, etc)
� Impulse Noise (shorts bursts of Broadband noise)

 Plant Induced

� Common Path Distortion (6MHz beats across entire spectrum)
� Transient Hum Modulation
� Excessive Gain

 Subscriber Induced

� Direct Pickup
� Malfunctioning Subscriber Devices
� Broadband noise from appliances
� Self Installs

Cable actually has to be more careful than BT about various things as there's no rate adaption on cable and there's active components out in the field, it's not just converting optical to electrical and done, there's amplification, attenuation and balancing of the two versus SNR to do, amongst other things.

In reply to a post by Ignitionnet:

It can't. Sky / TalkTalk don't have an IP Profile to be obtained.

I understand why Sky doesn't, they're the only ISP on the network, but I thought TalkTalk did wholesale services to other ISPs - and that was the reason I was given for BT having the profile in the first place?

In reply to a post by jchamier:

I understand why Sky doesn't, they're the only ISP on the network, but I thought TalkTalk did wholesale services to other ISPs - and that was the reason I was given for BT having the profile in the first place?

TalkTalk will be keeping track of connected speeds but they don't use an IP Profile in the manner BT Wholesale do. IP Profile is a BT-ism.

In reply to a post by Ignitionnet:

TalkTalk will be keeping track of connected speeds but they don't use an IP Profile in the manner BT Wholesale do. IP Profile is a BT-ism.

Gotcha!

Looks as though another couple of connections have gone in.

Max: Upstream rate = 24777 Kbps, Downstream rate = 79880 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 79891 Kbps

Down Up
SNR (dB): 6.0 14.9
Attn(dB): 0.0 0.0
Pwr(dBm): 14.1 7.2

Will try and avoid a modem restart as it seems unlikely we'll get that kind of sync again.

In reply to a post by Ignitionnet:

Looks as though another couple of connections have gone in.

Max: Upstream rate = 24777 Kbps, Downstream rate = 79880 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 79891 Kbps

Down Up
SNR (dB): 6.0 14.9
Attn(dB): 0.0 0.0
Pwr(dBm): 14.1 7.2

Will try and avoid a modem restart as it seems unlikely we'll get that kind of sync again.

Not fastest enough! Mine is 128/12

In reply to a post by adslmax:

Not fastest enough! Mine is 128/12

Yet you were so desperate for a service like mine that isn't fastest enough you repeatedly wrote to Openreach's CEO and over the course of two threads and the best part of a year obsessed over when you'd be able to get it. Though I have no doubt you'll order it anyway at some point. Welfare reform clearly fails even more emphatically when there are people struggling as they are while you can afford two super-fast connections.

I'll do this in a few points to save confusion:

1) This thread references crosstalk and its effects on connections, not a speed competition either between individual VDSL lines or Virgin cable.

2) As mentioned I'm getting a second line installed early next week and bonding them together to deliver about 150Mb down, 38Mb up, so even on that rather pathetic measure I'll win, and even when VM upgrade your service later in the year I'll still win due to having triple the upload and maybe 4-5% lower download.

3) Please kindly keep your thoughts to your own close social circle. If you don't have a social circle I heartily recommend getting one. If you put half as much energy into that and obsess about it half as much as you do broadband access you'll be the life and soul of the party, rather than the standing joke.

Ta.

Edited by deleted (Sat 04-Jan-14 22:13:58)

In reply to a post by Ignitionnet:

I'm getting a second line installed early next week and bonding them together to deliver about 150Mb down, 38Mb up,

VDSL cannot do bonding together.

In reply to a post by adslmax:

VDSL cannot do bonding together.

Nothing to stop the ISP doing bonding at the PPP level. I'm sure AAISP can offer this (for a incredible price though).

I believe there are a handful of ISP's that do offer 2 and 3 way bonded VDSL2 connections for business users.

In reply to a post by adslmax:

Not fastest enough! Mine is 128/12

ADSLmax please stop spamming the threads with pointless, stupid and misinformed posts! We are all totally sick of your posts!

I've posted links below showing the first 499 days attainable and sync on my connection. I was the first on the cabinet, and things seem to have fluctuated up and down over time, although never reaching the 55Mbps attainable I had in the first month. I've also added the interleaving graph as that pushes up the attainable speeds when interleaving is applied.

Sync speeds first 499 days
Attainable speeds first 499 days
Interleaving first 499 days

Oh, it would be so much simpler if we could attach pictures.

In reply to a post by adslmax:

In reply to a post by Ignitionnet:

I'm getting a second line installed early next week and bonding them together to deliver about 150Mb down, 38Mb up,

VDSL cannot do bonding together.

Pair bonding is part of the standard. An ISP could use multi link PPP. I could also run a point to point VPN from my router to a data centre or simply use per-flow load balancing which, while not proper bonding, would work well for applications that use multiple connections and deliver bandwidth efficiently to the household.

Still why let facts stop you?

Not that it matters that much of course. Hyperoptic and B4RN, amongst others, still deliver way more.

Good luck with your massive jitter and mostly poor service from VM. Why are you not banned yet with posting crud and trolling?

Any news on how the vectoring trial is going?

I probably have the longest line on my cabinet but not many lines running this way most go in other directions.

I was first on the cabinet and from day1 got the full 40Mb sync. At that time it was impossible to unlock the modem. When I finally unlocked the modem the figures from memory of max attainable were around 60Mbps. And moved up and down just a little.


When I upgraded to 80/20 my speeds were in te mid 50s but varied quite a bit and had an upstream of 9 Mbps with an attainable of 24 or more. After several visits the problem was resolved but I moved to an ECI mpdem (on a Huawei Cabinet). My speeds increased to around 58 Mbps in March '13. They actually increased slightly to give 59.5/60.5 over the next few months and have recently dropped back to about 59.0/59.5 ...

So, as more users have filed the cabinet I have not seen a significant change in my speeds which would suggest that I am not suffering from increased cross talk.

In reply to a post by Ignitionnet:

As an aside having a second line installed and enabled for FTTC imminently. Anyone done thing, and how much of a performance hit did you note on the original line?

Answering my own question in my case there was indeed a hit, attainable has dropped by about 3Mb down, and 1Mb up due to loss of 0.8dB SNRM in each direction.

Max: Upstream rate = 23850 Kbps, Downstream rate = 77384 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 79891 Kbps

Down Up
SNR (dB): 5.3 14.3

quite a small hit compared to what I have seen others report.

Throughput.

1/7/2014 8:52 AM GMT 115.98 Mb/s 26.38 Mb/s 33 ms London ~ 150 mi

I'm jealous... What router is doing the load balancing?

I was first on my CAB. And very close <50M from Fibre aggregation node (CAB is 20M away from FTTC cabinet). I was getting a perfect line about 105Mb down and 35Mb up with 0 errors... as more people joined I wouldn't notice much... a few more errors and maybe a couple of Mb of attainable lost...

My next door neighbor joined and it went down from 78Mb to 70Mb attainable... I imagine this is a classic example of cross-talk.

Tim

how fast is the 2nd line syncing?

In reply to a post by Chrysalis:

how fast is the 2nd line syncing?

I'm not sure. The Royal Fail have my 2nd Huawei sitting somewhere in the ether in between seller and myself.

EDIT: 73.9-ish, IP Profile is 71.55.

Edited by deleted (Tue 07-Jan-14 18:54:22)

A hit on Attainable is not really a hit though, is it?

It is a deferred hit that will land when that line resynchs.

In what way?

In reply to a post by BatBoy:

In what way?

The attainable has dropped, the line is currently synched higher than the attainable and when next resynched will sync lower due to the performance hit on the line.

The performance hit will manifest at the next resync event.

EDIT: In actual fact it shows at a very low level now with increased error rates. A touch of packet loss from time to time though nothing major.

Edited by deleted (Wed 08-Jan-14 11:09:18)

I got an update, either a fault has started on my line, or another install has hit me noticebly.

When disabling my tbb graph I noticed my latency jump up at 3am, and some packetloss at 5pm yesterday, checked the modem data and was a burst of crc errors lasted an hour or so. (silent noise no affect on snrm)

Was calm until 9.57am this morning and now getting FEC's in the 1000s although no crc's at all there is clearly something disruptive whether its crosstalk of a new line or a fault.

sync is now down to 62mbit as a result of the FEC overheads. so now approaching 45% lost signal.

--edit--

Bear in mind this may be a fault not crosstalk so has been raised with isp now.

Edited by Chrysalis (Wed 08-Jan-14 19:08:11)

I lost 10-12Mb/sec over about 3 months (from low 70s down to lower 60s), recovered a bit when something was upgraded in the cabinet relatively recently (about the same time as modem firmware updates were reported but I don't use the BT modem), currently syncing around 64 down, latency also increased over the initial months from below 10ms initially to over 20ms now.
Fritz!Box now has vectoring enabled firmware so just waiting for vectoring to be enabled at the cabinet (fingers crossed).

TP-Link TL-ER5120. 2 Openreach modems feeding it, it does PPPoE.

Hits around 124Mb down and 27Mb up on speed tests to a single machine. Tricky to get both WANs maxed at once.

In reply to a post by adslmax:

Not fastest enough! Mine is 128/12

Just for you, Phil. Excuse the poor upload, speed tester doesn't seem to like the load balancing too much.

http://www.speedtest.net/result/3219692669.png

Sorry to be slow posting this information; it took a while to get back to my historical data.

First, I posted here about my experiences of "attainable bandwidth vs crosstalk" last year.

In that post, I described how my attainable bandwidth dropped steadily over the life of a (long) connection, making it appear that crosstalk was increasing. However, a resync restored the level of the attainable bandwidth back up by 10Mbps. The thoughts of the forum then were that gradual bitswaps were having an effect.

I now have more data that I can add to the situation: Since that post, I have suffered one period where DLM intervened and added FEC+interleaving, and have had the firmware updated. Now, I don't seem to see the same kind of gradual drift in attainable speed.

Date      Attain Actual SNRM
01/2012   90     40            * On 17a profile, but only 40/10 package available
02/2012   91     40
02/2012   85     80     7.3dB  * 80/20 package turned on
03/2012   84     80     7.1dB
06/2012   83     80     6.9dB
07/2012   82     80     6.6dB
09/2012   82     80     6.5dB  * Voice fault occurs around here
11/2012   81     80     6.3dB
12/2012   78     80     5.4dB
01/2013   76     80     4.6dB
05/2013   72     80     3.0dB  * Immediately before resync
05/2013   83     80     6.7dB  * Immediately after resync (1st for 6 months)
05/2013   79     80     5.6dB  * one week after resync
05/2013   77     80     5.1dB  * two weeks after resync
06/2013   76     80     4.6dB
06/2013   75     80     4.3dB
07/2013   74     80     3.9dB  * stopped monitoring sync status for a while, until...
10/2013   86     75     5.9dB  * After DLM turned on FEC+interleaving; new firmware
11/2013   83     80     7.2dB  * DLM removed FEC+interleaving
01/2014   82     80     6.9dB  * Immediately before a resync
01/2014   82     80     7.0dB  * Immediately after a resync (1st for 2 months)

Since the firmware update, my "attainable" has stayed remarkably consistent.

The firmware update has made things very consistent for me also

In reply to a post by adslmax:

In reply to a post by Ignitionnet:

I'm getting a second line installed early next week and bonding them together to deliver about 150Mb down, 38Mb up,

VDSL cannot do bonding together.

Interesting *looks at said option on a customer site*

My max attainable going back 2 and a half years was 135Mbit, its now 110Mbit.

between september 2012 and now i have lost around ~6mb of the ~76mb i started with now syncing at 70.97 with 66mb speedtests. bt wholesale website still says i can manage the full 80/20 (i do get the 20 up) as indeed the fttc cab is 60 metres to the left of my house and the distance to the old cab is even shorter at about 40 metres, line goes from cab to top of pole about ~25 metres then the dropwire is about 15 metres to the roof the a further 5-6 metres to the master socket in the living room

could there be a possibility of some damage to the cabling around the fftc cab or elsewhere between me and it?

a few weeks ago the council decided to widen the road around the cab and redo footpaths surrounding the cab there is no grass between cab and path just tarmac that was dug up and replaced

im more than happy with what i have but i could of been getting 75-75mb throughput

Assuming I have no line fault this is my values.

Installed as 1st on cab 18th Feb 2014, distance 350-450 M from cab.
max attain: 83mbps down 24mbps up
sync: 74mbps down snrm 7db 20mbps up snrm 7db

5 days after installation:
max attain: 78mbps down 21mbps up
sync: 76mbps down 20mbps snrm 6.5db up snrm 7db

10 days after installation:
max attain: 74mbps down 21mbps up
Now DLM kicked in INP 3 , delay 8ms and interleave 1399 down , fast up
sync: 67mbps down snrm 6db 20mbps up snrm 7db

11 days after installation:
max attain: 72mbps down 21mbps up
DLM still active as before but interleave down to 1341
sync: 66mbps down snrm 6db 20mbps up snrm 7db

Today (28 days after installation):
max attain: 69mbps down 21mbps up
DLM as before (INP 3 delay 8ms)
sync: 62mbps down snrm 5.5db 20mbps up snrm 6db

So I have lost around 20% in total speed in 4 weeks as a result of crosstalk and
DLM interleave settings.

I am unsure how many are connected to the cab now but have read that the take up in this area is 3 times the national average so it could be quite a few. The cab
supports a total of 329 properties.
Lets hope it stops now as I am heading for Infinity 1 speeds in about 2 months at this rate.
BT - can we please have vector support soon to deal with all this crosstalk !

In reply to a post by Chrysalis:

2 weeks after I signed up when I unlocked my modem I had 110 max down and 36 max up. (dont know if it was higher before that).
3 weeks after signup I had max 90 down and 36 up.
4 weeks after signup I had max 73 down and approx 29 up.

Here is mine:
2 weeks after I signed up when I unlocked my modem I had 112 max down and 38 max up
3 weeks after signup I had max 112 down and 38 up
5 weeks today after signup I had max 112 down and approx 38 up.

Downstream Upstream
Attainable rate (kbit/s) 112740 38584
SNR margin (dB) 16.6 24.8
Line attenuation (dB) 0 0
Output power (dBmV) 12.5 -1.9
Connection up time: 32 Days 17 hours 22 minutes

Edited by adslmax (Thu 20-Mar-14 22:11:12)

Over the 18 months I've had fibre my max attainable rate has gone from around 85/26 to 70/22 with a drop from 73/23 to 70/22 when my new neighbour had fibre installed about 3 weeks ago.

Annoyingly his max attainable is 81/24.

I believe I was one of the first enabled on my local cabinet (about 2 months ago), and at first it would sync at 57mbps down and 12mbps up. Now it's at 50mpbs down and 9.5mbps with approx 20db attenuation. The vast majority of that loss of speed happened in the first few weeks, and it has since stabilised. It's very possible there was a large number of lines enabled at first so the stabilisation may be because the first rush of conversions is over. Hopefully it won't degrade at the same rate in the future.

The OR engineer measured the line length at 700m (it's about 500m to the cabinet by foot).

I rather suspect that people's experience in this area will depend on whether they were an early adopter and how close they are to the cabinet. Hopefully vectoring will resolve much of this, but I've no idea just how easily this is retrofitted.

Updated:

Downstream Upstream
Attainable rate (kbit/s) 103124 36209
SNR margin (dB) 12.1 21.3
Line attenuation (dB) 0 0
Output power (dBmV) 12.5 -1.9
Connection up time: 33 Days 9 hours 22 minutes

Should I worry about the attainable rate as it appear to drop for the first time today. Maybe more customers on my cabinet now?

Edited by adslmax (Fri 21-Mar-14 14:03:07)

Resurrecting this thread.

With the cabinet completely full stats have gone from:

Max: Upstream rate = 29421 Kbps, Downstream rate = 98020 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 79987 Kbps

To now:

Max: Upstream rate = 21782 Kbps, Downstream rate = 66332 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 65655 Kbps

Joys of xDSL services. Better than many but had faster 2 years ago so a little vexing.

EDIT: Should be interesting to see what happens when the second cabinet goes live and the crosstalk from that guy begins to bite. Ugh.

This'll teach me for driving demand within the community!

Edited by deleted (Sun 20-Jul-14 00:42:36)

don't know if will reply as you don't seem to reply to any of my posts now but, did you see any large drops at once or was it all gradual short drops of speed?

In reply to a post by Ignitionnet:

With the cabinet completely full stats have gone from:

Max: Upstream rate = 29421 Kbps, Downstream rate = 98020 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 79987 Kbps

To now:

Max: Upstream rate = 21782 Kbps, Downstream rate = 66332 Kbps
Path: 0, Upstream rate = 19999 Kbps, Downstream rate = 65655 Kbps

Easy fix - turn off openreach modem for 24 hours. Turn off modem main socket first and then unplugged from the master socket. DO NOT USE IT for 24 hours.

Then plugging in the master socket and switch on openreach modem, it will now get maximum max downstream / upstream rate.

I did mine and it worked a trick!

Lucky you had such a fast line to begin with. Your actual 14MB drop could have been 33MB if your max started at, say, 70MB...!

In reply to a post by Chrysalis:

don't know if will reply as you don't seem to reply to any of my posts now but, did you see any large drops at once or was it all gradual short drops of speed?

I wasn't monitoring it that closely. I had a look periodically, I don't run any kind of automated monitoring on the thing, so can't really advise on that.

I believe it stepped down rather than being a smooth downwards trend but that's just a belief.

I don't respond to many posts, nothing personal

In reply to a post by AndyPandy:

Lucky you had such a fast line to begin with. Your actual 14MB drop could have been 33MB if your max started at, say, 70MB...!

Tell me about it.

Pass.

Mine start off 113 Max with 38 Max but now down to 98 Max and 32 Max

In reply to a post by adslmax:

Easy fix - turn off openreach modem for 24 hours. Turn off modem main socket first and then unplugged from the master socket. DO NOT USE IT for 24 hours.

Then plugging in the master socket and switch on openreach modem, it will now get maximum max downstream / upstream rate.

I did mine and it worked a trick!

That, I believe, is nonsense, and was a pure fluke in your case.

Adding my recent experience, on 28 June at 0400, my sync speed dropped from about 72Mbps to 60Mbps, where it has remained. Prior to this it had been running at a low SNR margin of around 3dB for a while, now it is back up over 6. I don't know whether this is due to crosstalk but I can't think what else might have caused it. Interleaving was off both before and after the resync.

Edited by kasg (Sun 20-Jul-14 14:36:20)

I would imagine that you had some crosstalk that forced the SNR margin to go down to 3dB, eventually for whatever reason the line dropped (I'd imagine because of the low SNR), this then meant that the SNR went to the normal 6 and as such you lost the speed.
In a way you lost the speed when you had the SNR drop (not in reality but your max attainable would of dropped when your SNR dropped to 3 and as soon as a resynced kicked in the speed drop would happen).

That seems a fair assessment - my max attainable had been below actual for some time due to the low SNR margin, but I was surprised at the magnitude of the drop. The line had been stable at the higher speed (my highest ever sustained speed) for over two months. I am now (apart from a brief fault condition) at my lowest ever speed.

My line did something unusual.

At 1am one morning, quite a while ago now, the line went off, for a few minutes then came back up, it came back with a 4db snrm.

Now i would expect with a 6db target snrm, the possibility been my modem synced before others did so reduced crosstalk temporarily and then as the others synced up my snrm dropped. But my attainable speed matches a target 4db margin. So my sync speed of 75.7mbit, also had an attainable of 75mbit with a current snrm of 3.9db.

Lately the attainable has lowered a bit tho to 74mbit but I think with a 6db margin my sync speed would be way below that back into the 60s. The line has held like this, error rate not enough to upset DLM and uptime of over 3 months.

Edited by Chrysalis (Sun 20-Jul-14 16:09:39)

When I first got mine, got full 75mbps....

Now getting 50mbps @ around 200m - 250m from the PCP... Won't be surprised if it goes down further......

Yep affecting me a lot!

Full on 79.4Mbps on day 1 with 19.8 up.

3 months in down to 56Mbps up but still 19.8 up.

Two Openreach engineers have been out and test the line to the house and internally and see no problems. They asked BT to switch me to a different port in the cabinet but BT refused.

Had fttc since nov 2012 and for around the first year used to get a fairly consistent 76/19 Mbps, now i get 68 -70/18.5 Mbps

Edited by Davey_H (Mon 04-Aug-14 13:41:03)

I know there are more recent threads on crosstalk, but as this one poses a general question and I have posted on it before (and replying to myself so as not to annoy anyone else!) I thought I'd add a little more information after looking at some old logs.

I had been syncing at 72152 for over two months (higher, incidentally, than I had managed since the very first few days after installation two years previously). On 26 June, some time between 1458 and 1808, my SNRM dropped from 5.9 to 2.8. The sync held at 72152 until 4 July, when the modem resynced at 60373, and it has remained there or thereabouts, with a SNRM of about 6, ever since.

So, something happened on 26 June. Could this really just have been a neighbour getting FTTC? Seems a bit drastic. Whatever it was, I am looking forward to vectoring, which hopefully will get me back up to full speed.

In reality I am not at all concerned about getting speeds of around 60 Mbps rather than 70 Mbps as it makes no practical difference, but I am concerned that it took such a large hit all in one go and that it could happen again.

well see my recent thread, if my recent issue is further crosstalk I have gone down from 110 to 53mbit. Still on fast path so not reduced by DLM. Although I currently have FEC on fast path it appears to have not had any significant affect on sync speed and I Was down to 55 without FEC anyway.

Find someone else with a DS sync of 55 who has full US speed with nearly 10db margin (and that is with power cutback applied on the US also). My DS seems massively hindered.

Edited by Chrysalis (Mon 01-Sep-14 17:18:24)

In reply to a post by kasg:

I know there are more recent threads on crosstalk, but as this one poses a general question and I have posted on it before (and replying to myself so as not to annoy anyone else!) I thought I'd add a little more information after looking at some old logs.

I had been syncing at 72152 for over two months (higher, incidentally, than I had managed since the very first few days after installation two years previously). On 26 June, some time between 1458 and 1808, my SNRM dropped from 5.9 to 2.8. The sync held at 72152 until 4 July, when the modem resynced at 60373, and it has remained there or thereabouts, with a SNRM of about 6, ever since.

So, something happened on 26 June. Could this really just have been a neighbour getting FTTC? Seems a bit drastic. Whatever it was, I am looking forward to vectoring, which hopefully will get me back up to full speed.

In reality I am not at all concerned about getting speeds of around 60 Mbps rather than 70 Mbps as it makes no practical difference, but I am concerned that it took such a large hit all in one go and that it could happen again.

That's what pretty much happened to mine, started off at 52 then went down to 40 in pretty much 1 hit and then again from 40 down to the current 32 again all in one go, both of them are thought to be because of crosstalk so if it's like mine then yes it could easily happen again on your line.

In reply to a post by kasg:

So, something happened on 26 June. Could this really just have been a neighbour getting FTTC? Seems a bit drastic. Whatever it was, I am looking forward to vectoring, which hopefully will get me back up to full speed.

I saw similar instances on my connection.

SNRM would drop suddenly by 2 dB or so & remain there for a few days.

The connection then resynced with SNRM back to 6 dB, but with lower sync speeds.

This happened around 5 times over a 12 month or so period.
Previously able to sync at around 30 Mbs, occasionally 34 Mbps upward, it now syncs at around 19 Mbps when Interleaving is ON & at around 21 Mbps when it is on fastpath.



A couple of visiting engineers & my own stats records have been unable to determine the cause & the assumption is that it is indeed due to increased crosstalk as more users become connected.





We had a fairly brief power cut in the area last night & as the HG612 modem does sync quite quickly when powering up again, it appears my connection resynced slightly earlier than some other connections when power was restored.

I ended up with a sync speed of 24975 Kbs & attainable rate of 30944 Kbps.

However, by the time this resync was captured by my monitoring program (a minute or so later), other connections must have become live again as my DS SNRM was (& still is) around only 0.9 dB.

I fully expect my connection to resync within the next few days, back down to between 19 & 21 Mbps.


I understand that a single new connection can have a drastic effect crosstalk-wise.
It apparently depends exactly where that pair sits within the cable bundle as to how severe the effect is.



So yes, maybe a single new connection could have quite a devastating effect on sync speeds/attainable rates.

In reply to a post by Bald_Eagle1:

However, by the time this resync was captured by my monitoring program (a minute or so later), other connections must have become live again as my DS SNRM was (& still is) around only 0.9 dB.

0.9, wow, I thought 2.8 was precarious enough!

In reply to a post by Bald_Eagle1:

I understand that a single new connection can have a drastic effect crosstalk-wise.
It apparently depends exactly where that pair sits within the cable bundle as to how severe the effect is.

So yes, maybe a single new connection could have quite a devastating effect on sync speeds/attainable rates.

Then it looks like I got off very lightly for over 2 years. My "clean" range on the BT wholesale checker is 60 to 79.5 so I am right at the bottom end now.

my (Current) clean range is 69.5 to 80, I say current because I suspect BT will change it if I become enough of a nuisance, when I had engineers out earlier in the year they reduced my estimate trying to be clever.

I am 17 mbit below the bottom of my clean range and 5 mbit below the bottom of my impacted range. Plus in the last 2 hours my dsl now keeps dropping, so things seem to be getting even worse.

In reply to a post by kasg:

I know there are more recent threads on crosstalk, but as this one poses a general question and I have posted on it before (and replying to myself so as not to annoy anyone else!) I thought I'd add a little more information after looking at some old logs.

I had been syncing at 72152 for over two months (higher, incidentally, than I had managed since the very first few days after installation two years previously). On 26 June, some time between 1458 and 1808, my SNRM dropped from 5.9 to 2.8. The sync held at 72152 until 4 July, when the modem resynced at 60373, and it has remained there or thereabouts, with a SNRM of about 6, ever since.

So, something happened on 26 June. Could this really just have been a neighbour getting FTTC? Seems a bit drastic. Whatever it was, I am looking forward to vectoring, which hopefully will get me back up to full speed.

In reality I am not at all concerned about getting speeds of around 60 Mbps rather than 70 Mbps as it makes no practical difference, but I am concerned that it took such a large hit all in one go and that it could happen again.

I lost over 11dB of SNR on the Downstream a few months ago within the space of an hour so it's quite possible.

My max attainable has went down from 124 mbps to 108

but my sync is still max 80/20

In reply to a post by kasg:

0.9, wow, I thought 2.8 was precarious enough!

Have a look at my SNRM graph in MyDSLWebStats.

It'sbeen pretty damned steady at around 0.9 dB for the last 26 hours or so.

I wish I could tweak it down permanently as per for ADSL connections.

In reply to a post by Chrysalis:

my (Current) clean range is 69.5 to 80, I say current because I suspect BT will change it if I become enough of a nuisance, when I had engineers out earlier in the year they reduced my estimate trying to be clever.

They did this to me too, but I'm now below that estimate too, lost around 10Mbps from my already flakey unreliable line because of what I assume is crosstalk

well see my thread seems I may get a fix as BTw have recognised it as a fault.

Well well well, at about 00.30 today the connection dropped for a few minutes then came back synced 6Mbps higher at 66969 - I'd pretty much given up on that happening now after two months. What is odd is that the SNRM is only 4.3. yet the attainable is 73472 - I would expect it to be lower than the sync. Interleaving is still off.

there is a banding that caps at 67 which might explain the gap between sync and attainable.

however the attainable is odd considering your snrm.

a guess is yopu had temporary improved line conditions which would have got you a approx 73mbit sync but you got 67mbit due to banding, and when your temporary improvement stopped the attainable seems to have malfunctioned somewhat, only a weak guess tho.

It could be that the "temporary improved line conditions" were caused by a DSLAM outage.

If the modems resynced before (some of) the neighbours, it could have the faster speed, but the SNRM value drops as more modems gain sync.

yeah and ironically the banding has probably saved the sync, as I think he wouldnt have held onto 73.

Gone from full 79999kbps to 65500kbps. Not sure how full my cab is but BT are there literally every day. All of my neighbours appear to be on FTTC now.

I'm 300m from the cab. Attenuation is 12db.

Edited by wolvesmad (Fri 12-Sep-14 10:21:57)

Here is a graph of my line stats since the beginning of February 2014. Make of it what you will with regards to cross talk but I definitely have been affected I'd say.

Note I did have an issue with the cabinet being broken between Jan and April.

Dotted = Max attainable line speed.
Red = Downstream SNR
Orange = Upstream SNR
Blue = Downstream Sync
Green = Upstream Sync
Black = Uptime

Stats image: http://i.imgur.com/Jiitjyg.png

Edited by deleted (Fri 12-Sep-14 11:38:33)

In reply to a post by Ignitionnet:

Given Openreach are hopefully, at some point rolling out vectoring I thought it'd be interesting to see how people are being affected by crosstalk.

Also might help give some indication of the kind of loss people who aren't hitting full rate can expect. I can imagine BDUK enabling a fair amount of longer lines.

Here's Mine:

Only one on cabinet.

150+ lines down.

I have started to process the PSD information that we capture during a PQ test and its quiet interesting that you can see the VDSL cross talk on the trace, see this example: http://imgur.com/HBtANBQ

In reply to a post by Chrysalis:

yeah and ironically the banding has probably saved the sync, as I think he wouldnt have held onto 73.

No, probably not, so pretty happy with 67ish for now.

In reply to a post by kasg:

No, probably not, so pretty happy with 67ish for now.

Well that didn't last - I had to power off the modem (well, strictly speaking I didn't have to, but I was trying to eliminate the possible cause of a connection problem I was having) and when it came back I was back to 60M actual and attainable with an SNRM of 6ish. So it seems that the higher speed was due to some failure that caused a resync of my and possibly neighbours' modems resulting in less crosstalk and therefore a higher speed. I still don't really understand why the attainable speed held at 73M throughout. I might try a resync at the sort of time it happened before - maybe a neighbour is powering off overnight.

Edit: my problems that caused me to reboot the modem were almost certainly due to a Plusnet outage (82816).

Edited by kasg (Mon 15-Sep-14 16:31:16)

How to tell if crosstalk start to appear in my cabinet?

@ Ribble can you please tell me how many users on my cabinet 8 (cuckoo oak) thanks.

Edited by adslmax (Thu 02-Oct-14 17:52:21)

In reply to a post by adslmax:

How to tell if crosstalk start to appear in my cabinet?

It will get slower!

Your attainable rate and sync speed will gradually start to lower.

Mine seems to have stabilised at 67Mb now.