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Author Topic: VDSL2 Errors  (Read 3372 times)

.Griff.

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VDSL2 Errors
« on: October 26, 2011, 08:46:52 AM »

Firstly apologies in advance if this is in the wrong section. I'm aware the section in titled "ADSL issues" but I couldn't see anywhere more suited to this issue.

In August 2010 I had FTTC/VDSL2 installed. Being something of a internet/network geek I made sure I asked lots of questions about my line during the installation process and even persuaded the Openreach engineer to run through various diagnostic tools on his JDSU. The copper line to my cabinet was confirmed at 320 metres and I synced at the full 40Mbps/10Mbps you'd expect at such a short distance. My IP Profile was 38718Kbps and everything was great for the next few months.

In January of this year I started to experience problems with the connection. Namely loss of sync numerous times a day, periods of 10 - 15 minutes without connection numerous times a day and general instability. All of these line drops had an impact on my IP Profile which dropped from rock solid 38,718Kbps to in the region of 25,000Kbps. Clearly something wasn't right and My ISP (IDNet) confirmed a fault and an OR engineer was sent out. He ran various tests with an EXFO and confirmed the presence of "errors" on the line. The next four hours were spent testing the internal wiring, DP, and at the cabinet before he gave up and passed the job back to OR. A few days later I was told that the errors and line instability had been caused by "the extreme weather conditions" we experienced in January.

Over the next 9 months I'd often see my IP Profile change week by week. One week I'd have a high IP Profile and the DLM would put me on Fastpath, the next my IP Profile was low and I'd find interleaving has been applied to the line. This cycle continued until late September when I had an SFI visit from OR and they eventually found a HR (High resistance) fault on the line. This was swapped for a spare pair and since then my connection seems stable however my IP Profile still hasn't recovered to the highest available and I'm still stuck with interleaving in place.

This essentially brings me to the reason I'm here. Line errors. Like quite a few others I've unlocked my Huawei VDSL2 modem and I can finally see all the line stats and error counts for my connection. Immediately I was concerned at the amount of errors displayed and the speed in which they were increasing. I spent the next few days doing a little research and asking other FTTC/VDSL2 users for their error counts so I could make a comparison. Other users were typically seeing very few CRC errors, in the range of 0 - a few thousand depending on modem uptime, and very few if any HEC errors.

My modem has been synced now for 17 days (25468 minutes to be exact). In that time I have accumulated 19998782 (Nineteen million) CRC errors and 6984602 (Six million) HEC errors. That's 12 CRC errors and 4 HEC errors for every second of every day over the last 17 days. This rate of error continues regardless of whether the internet is in use or not.

I fully appreciate errors can, and do, occur but I'm keen to hear from others on whether they see that amount as normal, inconsequential or indeed very strange and something to be concerned about.

Any opinions?
« Last Edit: October 26, 2011, 09:00:27 AM by .Griff. »
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Bald_Eagle1

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Re: VDSL2 Errors
« Reply #1 on: October 26, 2011, 09:37:03 AM »


TBB's speedtest has never given me an accurate result.


Hi .Griff. & welcome to Kitz

Are you by any chance the griff_90 from the TBB forum?

If so, your connection seems to be holding its own reasonably well (apart from your comments in your other post at http://forum.kitz.co.uk/index.php/topic,10110.msg203144.html#msg203144 ).
Do you actually notice any speed/connection issues in day-to-day use?

Have you noticed whether you have been switched to the 17a profile yet?

# xdslcmd info --show             
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Max:   Upstream rate = 6454 Kbps, Downstream rate = 23608 Kbps
Path:   0, Upstream rate = 6435 Kbps, Downstream rate = 20345 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 8c
TPS-TC:         PTM Mode
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    6.3       5.9
Attn(dB):    0.0       0.0
Pwr(dBm):    9.6       3.2

I am still stuck at the 8c profile with a "problematic" connection that my ISP & BT don't appear to have any interest in "fixing".
I’m “hoping” the issues will be resolved when/if I get switched to 17a.

If you fancy a long, very long read, take a look here:-

http://forum.kitz.co.uk/index.php/topic,9726.0.html

See the attachments for my poor connection, & someone else's decent connection.


Paul.
« Last Edit: October 26, 2011, 09:48:15 AM by Bald_Eagle1 »
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.Griff.

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Re: VDSL2 Errors
« Reply #2 on: October 26, 2011, 09:43:09 AM »

Hi Paul and thanks for the welcome.

I am indeed griff_90 from TBB.

I'm still on 8c and one of the reasons I'd like to get to the bottom of these errors is with 17a around the corner I don't want to be in the situation where I cannot take advantage of it as there's an underlying issue with the connection somewhere.

I'm kind of stuck in limbo at the moment however as my ISP really don't seem to have any interest in the errors, huge that they are, however Ms Garfield at OR has taken an interest so I may yet get somewhere.

One of the reasons I signed up here was it's been an invaluable source of information for me and I was hoping one of the resident experts would jump up and confirm the amount of errors I'm accumulating is definitely not normal. It would give me more confidence to fight my corner with my ISP even more.

As for day to day use I can't really say I see any problems other than the fact my IP Profile isn't what it should be and interleaving is in place which wasn't the case from August 2010 to January 2011.
« Last Edit: October 26, 2011, 09:45:11 AM by .Griff. »
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Bald_Eagle1

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Re: VDSL2 Errors
« Reply #3 on: October 26, 2011, 09:58:45 AM »

Hi Paul and thanks for the welcome.

I am indeed griff_90 from TBB.

I'm kind of stuck in limbo at the moment however as my ISP really don't seem to have any interest in the errors, huge that they are, however Ms Garfield at OR has taken an interest so I may yet get somewhere.

One of the reasons I signed up here was it's been an invaluable source of information for me and I was hoping one of the resident experts would jump up and confirm the amount of errors I'm accumulating is definitely not normal. It would give me more confidence to fight my corner with my ISP even more.


I'm definitely a resident expert.
Unfortunately, my expertise only extends to noting how BT engineers can completely ruin a previously good connection, & how BT & my ISP refuse to sort it out once & for all.

Paul.

P.S.
Do you recognise this attached graph?
 
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.Griff.

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Re: VDSL2 Errors
« Reply #4 on: October 26, 2011, 10:04:19 AM »

Yeah I recognise it.

Here's mine for comparison -

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Bald_Eagle1

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Re: VDSL2 Errors
« Reply #5 on: October 26, 2011, 10:23:20 AM »


Yeah I recognise it.



Haha, & so you should recognise it, it is actually from your own stats anyway, just presented via a slightly updated script.

If you want to know why/how, send me a PM.

Paul.
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.Griff.

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Re: VDSL2 Errors
« Reply #6 on: October 26, 2011, 10:30:39 AM »

Haha.. That would explain why it's virtually identical. Clearly the updated script has resulted in a slight difference.

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Bald_Eagle1

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Re: VDSL2 Errors
« Reply #7 on: October 26, 2011, 12:59:23 PM »

Haha.. That would explain why it's virtually identical. Clearly the updated script has resulted in a slight difference.

Different days?

One from 6th Sept & the other from 8th?

Paul.
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.Griff.

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Re: VDSL2 Errors
« Reply #8 on: October 26, 2011, 01:08:41 PM »

I only supplied the log file once so I'm assuming both graphs have been extrapolated from the same raw data.
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Bald_Eagle1

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Re: VDSL2 Errors
« Reply #9 on: October 26, 2011, 05:48:34 PM »

I only supplied the log file once so I'm assuming both graphs have been extrapolated from the same raw data.

Hi Griff,

Just in case you don't notice (easily missed), I have sent you a PM.

Paul.
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