Creeping Latency

My latency seems to be climbing out of control.

A few weeks ago it was about 17-18ms, it jumped to 26-27ms and after a high number of connection drops is now up to 33ms.

Here are the BQM snapshots for the last couple of latency "jumps"

BQM 22nd February
BQM 28th March

On the days preceding these there were quite a few drops in the connection, and it seems that upping the base latency is stabilising, but how far cab that go?

BTW this is not just BQM, I'm also seeing the same on the stats from my Unifi router.

And current line stats

---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
Running Mode : 17A
State : SHOWTIME
DS Actual Rate : 32400000 bps
US Actual Rate : 6149000 bps
DS Attainable Rate : 44701656 bps
US Attainable Rate : 6277390 bps
DS Path Mode : Interleave
US Path Mode : Interleave
DS Interleave Depth : 1557
US Interleave Depth : 129
NE Current Attenuation : 23 dB
Cur SNR Margin : 7 dB
DS actual PSD : 4. 9 dB
US actual PSD : 12. 4 dB
NE CRC Count : 16
FE CRC Count : 12122
NE ES Count : 1
FE ES Count : 6444
Xdsl Reset Times : 0
Xdsl Link Times : 24
ITU Version[0] : fe004452
ITU Version[1] : 41590000
VDSL Firmware Version : 05-07-06-0D-01-07 [with Vectoring support]
Power Management Mode : DSL_G997_PMS_L0
Test Mode : DISABLE
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 33 dB
Far SNR Margin : 6 dB
CO ITU Version[0] : b5004946
CO ITU Version[1] : 544ed086
DSLAM CHIPSET VENDOR : < IFTN >

The drops in connection might be indicative of a line fault, the changes in latency might be you noticing DLM tweaks to stabilise the line.

Have you asked your service provider to test your line and FTTC connection ?

ISP (Plusnet) say no faults found, as they do

And yes I assume it is DLM tweaking to try to stabilise, but can it keep going? There were a couple drops today, so it's still not got there yet! So I assume its going to carry on doing its stuff.

Also my daughter is now starting to moan about ping times, as would be expected, with a change from 17-34ms to the base latency.

When you spoke to PlusNet did you speak about the regular drops of connection rather than the latency - it is the connection drops that are more likely to be recognised as a fault? Are you sync speeds reducing each time the connection drops or is it just the latency that is affected?

What is it your daughter is using that is latency sensitive? Very few things will see much of a difference between 17ms and 34ms latency - even gaming shouldn't care about that sort of change.

It was about the connection drops I spoke to them, but they just said the "systems" were putting in measures to stabilise, which I assumed meant DLM. And when they did their check the line had no drops for 7 days, they timed it perfectly

She's into the FPS games and says its made a difference, but I'm not a gamer and just want a stable line.

Your best bet of getting somewhere with Plusnet is to post in their users forums, explain the problem and ask one of the moderators to run a GEA Test for you and take it from there.

It's a while since I was a Plusnet customer, but there used to be some very helpful staff members on the user forums that would go the extra mile.

https://community.plus.net/t5/Forum/ct-p/Forum

I pushed them and they said they did a GEA test, and all was ok


Test Outcome Pass
Test Outcome Code GTC_FTTC_SERVICE_0000
Description GEA service test completed and no fault found .
Main Fault Location OK
Sync Status In Sync
Downstream Speed 32.4 Mbps
Upstream Speed 6.1 Mbps
Appointment Required N
Fault Report Advised N
NTE Power Status PowerOn
Voice Line Test Result Pass
Radio Frequency Ingress Not Detected
Repetitive Electrical Impulse Noise Not Detected
Cross Talk Not Detected
Estimated Line Length In Metres 854.2
Upstream Rate Assessment Reasonable
Downstream Rate Assessment Low
Interference Pattern Regular Interference Observed Daily
Service Impact No Impact Observed
Interference Duration Longest Occurrence From09:00to07:00
Interference Location Customer Premise
Interference Observed In Days 0
Home Wiring Problem Not Detected
Downstream Policing Discard Rate 0.0
Customer Traffic Level Upstream and Downstream traffic detected
Technology VDSL
DP Type External
Profile Name 0.128M-35M Downstream, Interleaving High - 0.128M-7.2M Upstream, Error Protection Off
Time Stamp 2021-04-06T03:00:00
0.0
Parameters MIN MAX AVG
Down Stream Line Rate 7.0 Mbps 34.9 Mbps 32.7 Mbps
Up Stream Line Rate 2.2 Mbps 7.1 Mbps 6.4 Mbps
Up Time 754.0 Sec 900.0 Sec 899.1 Sec
Retrains 0.0 6.0

But it isn't OK. It is rubbish. Your line profile is banded, that is capped at 35Mbps and it has high interleaving.

Is your sync speed still 32.4Mbps, that is an even lower banded speed.
The profile shown on the test was on 6th April so is a bit out of date.

You must have had drops on the line as there is a downstream speed of 7Mbps recorded at some point. Upstream is banded as well and also shows a low speed of 2.2Mbps.

Try posting on the forum you won't get any useful help from phone support. It definitely looks like you have line fault that needs investigation.

Agreed. Low and erratic upstream sync speed normally points to a line fault.

Edited by Grimers (Thu 08-Apr-21 17:05:59)