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Author Topic: Upstream Error Seconds going crazy  (Read 2697 times)

JamesK

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Upstream Error Seconds going crazy
« on: February 22, 2018, 11:39:48 AM »

Hi All,
Since 6pm-ish last night my Upstream Error Seconds have gone through the roof. I've got no idea what's causing it. Downstream E/S and SES are unchanged (for my line), but for some reason upstream is going crazy. I'm JamesK on MDWS.
Would appreciate some insight...
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re0

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Re: Upstream Error Seconds going crazy
« Reply #1 on: February 22, 2018, 12:16:17 PM »

My guess it is something to do with the actual upstream and attainable being so close. I speculate that the modem is unable to bitswap based on the Bit Allocation Table (BAT) it has because it decided that there is nowhere else to allocate at all. I could be completely wrong (I'm still learning :D), so let's see what others have to say. :)

I would say that if this has never happened before then it would be safe (and probably advisable) to reboot the router so it can get a new BAT which hopefully will allow more bitswap maneuver on the upstream. Though, looking at the colours on the traffic lights and taking the thresholds into account, the damage has already been done and the DLM may punish your line. :(
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jaydub

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Re: Upstream Error Seconds going crazy
« Reply #2 on: February 22, 2018, 12:38:40 PM »

There's nothing screaming at me.

Your Bit's Tone allocation has no bits allocated at higher frequencies but that hasn't changed recently.

Your Quiet Line and HLOGs look OK to me.

I would follow re0's suggestion of rebooting your router, just in case it's your modem having an aberration.

It's probably worth leaving it off for 30 minutes as that is less likely to tempt DLM into action.

Do you have any other VDSL kit you can try?
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JamesK

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Re: Upstream Error Seconds going crazy
« Reply #3 on: February 22, 2018, 12:53:43 PM »

I've got a Zyxel VMG1312-B10D I can try on the line. I wonder how hard DLM will hit me for this....
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kitz

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Re: Upstream Error Seconds going crazy
« Reply #4 on: February 22, 2018, 01:54:58 PM »

Something happened at 10pm last night which triggered lots of CRC's which in turn caused the Err/Secs.
Looking at your upstream breakdown U0 is very jittery.   My own line on an ECI cab can also see such bouts but on the downstream.  Occasionally a CRC spike will trigger Err/Secs to go manic and it will get 'stuck' until I power down the modem for a short while.

I've not done a thorough analysis of your line, but your downstream appears to suffer from bouts of REIN and SHINE spikes.   

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JamesK

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Re: Upstream Error Seconds going crazy
« Reply #5 on: February 22, 2018, 02:08:05 PM »

I've not done a thorough analysis of your line, but your downstream appears to suffer from bouts of REIN and SHINE spikes.

I had issues around June last year where I had a huge spike of errors... link to post .This immediately resulted in banding. I think you commented at the time it was agressive behaviour from DLM. Previous to this the line had been stable with relatively few errors.

I've done all I can to ensure everything is 'clean' within my home, yet I repeatedly see big dips in the SNRM dB on the downstream, with no particular pattern to when they occur. Despite getting the line back to fastpath by capping the sync speed, the banding remained. It was only lifted two weeks ago when I moved to Plusnet.

I remotely rebooted the modem about an hour ago, and the US errors have stopped occurring. The waiting game will now be to see how bad the DLM intervention will be, which I assume will happen at some point tomorrow. Any thoughts on how severe DLM will punish the line?
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GaryW

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Re: Upstream Error Seconds going crazy
« Reply #6 on: February 22, 2018, 02:12:17 PM »

Last time I had a "red" day, DLM increased my interleaving for just over a week but no change to banding.  (ECI cab as well)
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Ixel

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Re: Upstream Error Seconds going crazy
« Reply #7 on: February 22, 2018, 02:15:38 PM »

I imagine you'll find only the interleaving will change (INP/delay), banding in my experience has mainly been used for situations of rapid re-syncs in a short timeframe or the MTBR threshold being exceeded.
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JamesK

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Re: Upstream Error Seconds going crazy
« Reply #8 on: February 22, 2018, 02:28:37 PM »

Last time I had a "red" day, DLM increased my interleaving for just over a week but no change to banding.  (ECI cab as well)

Does DLM take action based simply on the fact that you've gone over the 2,800 error threshold? Or does it respond according to how far over the threshold you went?

Last time DLM intervened for me I got hit with interleaving and banding straight away. My concern with 12,000 upstream errors is I'll get hit hard by it.
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GaryW

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Re: Upstream Error Seconds going crazy
« Reply #9 on: February 22, 2018, 02:39:39 PM »

I can't answer that one I'm afraid - mine was around 1800 ES and 100 SES so not at the same level as yours.
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kitz

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Re: Upstream Error Seconds going crazy
« Reply #10 on: February 22, 2018, 09:34:51 PM »

Looks like power cycling had stopped it in its tracks so thats one thing.

>> Does DLM take action based simply on the fact that you've gone over the 2,800 error threshold?


Can't say for certain, but from observations on downstream action,  it will apply INP regardless of how far over the MTBE it went.
Last year I got ~15k Err/Secs in about 6hrs before I got home and noticed it.  DLM applied INP 3 in exactly the same way as if I'd only slightly gone over.
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JamesK

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Re: Upstream Error Seconds going crazy
« Reply #11 on: February 23, 2018, 11:04:29 AM »

DLM Intervened at 10:00 this morning. Interleaving applied on the upstream. INP 2.50 / delay 8.0. As generally the upstream errors are pretty much zero, would it be a safe bet to assume that DLM will fairly quickly intervene again to remove the upstream interleaving?

Code: [Select]
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Last initialization procedure status:   0
Max:    Upstream rate = 8189 Kbps, Downstream rate = 42828 Kbps
Bearer: 0, Upstream rate = 8175 Kbps, Downstream rate = 39973 Kbps

Link Power State:       L0
Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17a
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        7.5             6.2
Attn(dB):        23.4            0.0
Pwr(dBm):        6.0             6.0
                        VDSL2 framing
                        Bearer 0
MSGc:           18              27
B:              239             79
M:              1               1
T:              64              56
R:              0               16
S:              0.1911          0.3112
L:              10048           2468
D:              1               103
I:              240             96
N:              240             96
                        Counters
                        Bearer 0
OHF:            1117856         262589
OHFErr:         95              0
RS:             0               1153622
RSCorr:         0               0
RSUnCorr:       0               0

                        Bearer 0
HEC:            1271            0
OCD:            50              0
LCD:            50              0
Total Cells:    263516691               0
Data Cells:     4115432         0
Drop Cells:     0
Bit Errors:     0               0

ES:             1773            20
SES:            41              0
UAS:            59              48
AS:             3431

                        Bearer 0
INP:            0.00            2.50
INPRein:        0.00            0.00
delay:          0               8
PER:            3.06            13.12
OR:             62.55           20.12
AgR:            40035.61        8194.65

[Moderator edited to fix broken tags and replace [quote][/quote] with [code][/code].]
« Last Edit: February 23, 2018, 06:53:59 PM by burakkucat »
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re0

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Re: Upstream Error Seconds going crazy
« Reply #12 on: February 23, 2018, 11:23:00 AM »

You had 12,006 ES yesterday on the upstream. :-X Interesting to observe that the problem pretty much went full-on during 21st after 18:00 then ceased after 13:00 on 22nd.

If the problem is no longer present, and if the DLM has not previously intervened recently, then it should remove it if it feels fit pretty soon.

You have to view the information on thresholds for the DLM that are public as a guideline and not precise as there may be unpublished information and changes made to the system.
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JamesK

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Re: Upstream Error Seconds going crazy
« Reply #13 on: February 23, 2018, 12:41:04 PM »

You had 12,006 ES yesterday on the upstream. :-X Interesting to observe that the problem pretty much went full-on during 21st after 18:00 then ceased after 13:00 on 22nd.

It seems for some reason the modem decided to go a bit crazy around 18:00 on 21st, no idea why. As soon as I rebooted it, the issue stopped.
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re0

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Re: Upstream Error Seconds going crazy
« Reply #14 on: February 23, 2018, 05:21:05 PM »

Well, it does seem like there was a slightly elevated level of FECs on the 20th around midday, which of course preceeds the issue you mentioned in regards to high levels of ES. But you didn't start seeing CRCs (which lead to ES) until the 21st as previously mentioned.

While this may be speculative, I thought it was something to do with the Bit Allocation Table (BAT). I have just taken another look and it seems that around the time when the FEC levels started elevating at around appear to coincide with sudden bitswaps on the upstream at around 11:40 and 12:40 on the 20th on a line which, from what I can see, does not experience a lot of bitswaps in that direction.

There is only one reason why I doubt myself and that is because if there is an issue with the BAT (that the modem gets when it syncs) then usually the SNRM is usually on a downward spiral as the average SNRM across the tones in use plummets as it struggles to find and allocate tones that have the required margin.

Hopefully someone can add to, or debunk this speculation. :)
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