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M100 performance problem

Hi,

Posting here hoping the Forum staff can pick up if there is a problem we can sort.

My broadband has been experiencing periods of abysmal performance that is starting to seriously impact things like work Video and Audio calls and the like.  It appears to have started around a week ago and is now generally underperforming but intermittently, with no discernible pattern, performance becomes so bad that calls drop out and everything stops until it recovers.

When this first happened last week performance dropped down through the floor and I could get maybe 8-12Mb/s download and 1-2Mb/s upload and periodically the upload would drop out completely, this would be regardless of time of day or usage and true even if I connected the laptop directly to the hub rather than the Cisco router it normally connects to.  It got slightly better on saturday morning with downloads returning to above 50Mb/s speeds but uploads still being limited.

Running the online tests reports nothing wrong but did offer an upgrade to a hub 3 (the service was still on a hub 1).  Installing the hub3 on Saturday night seemed to have improved things in that overall speeds improved dramatically and I was able to get up around full speed again but this then progressively got worse and today has been very bad again.

I've had a broadband quality monitor running since last week and the live link is;

https://www.thinkbroadband.com/broadband/monitoring/quality/share/4a9136a21f9b53e4ffd97d3bf609e77dd8...

and you can generally see that where the problems occur latency goes through the roof and dropped packets get to the point where traffic is killed.  I had thought this might be a problem higher up the line, or perhaps impedance due to water seeping into the junction box outside or somesuch, but interestingly in one of the most recent events I was able to run a series of flood pings internally across the local link to the 192.168.100.1 address of the hub3 and I was observing high packet loss there as well whereas normally it is 100% clean.  There's zero errors on the Cisco during any problem event.

The connection is 100% wired, I've tried both with the Cisco router in place and with a laptop directly in the hubs port 1 (it's in modem mode) and the downstream/upstream stats + log are below.

If anyone can see anything that points to a specific cause that I can request someone to look into then any comments welcome.

Jacqui

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID
1 139000000 -0.4 34 256 qam 1
2 147000000 -0.7 36 256 qam 2
3 163000000 0.2 34 256 qam 4
4 171000000 -0.7 37 256 qam 5
5 179000000 -1.2 33 256 qam 6
6 187000000 -0.4 34 256 qam 7
7 195000000 -0.2 40 256 qam 8
8 203000000 -1.2 38 256 qam 9
9 211000000 -1.9 40 256 qam 10
10 219000000 -1.5 38 256 qam 11
11 227000000 -1 40 256 qam 12
12 235000000 -1.9 40 256 qam 13
13 243000000 -2.7 40 256 qam 14
14 251000000 -2.9 38 256 qam 15
15 259000000 -1.5 40 256 qam 16
16 267000000 -1.9 38 256 qam 17
17 275000000 -3 40 256 qam 18
18 283000000 -2.7 38 256 qam 19
19 291000000 -1.5 40 256 qam 20
20 299000000 -1.7 40 256 qam 21
21 307000000 -3.5 38 256 qam 22
22 315000000 -2.7 38 256 qam 23
23 323000000 -1.7 40 256 qam 24

Downstream bonded channels
Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors
1 Locked 34.9 13762374 10589531
2 Locked 36.8 1807208 699210
3 Locked 34.4 13609559 13799102
4 Locked 37.9 476374 307184
5 Locked 33.9 18324502 6064426
6 Locked 34.6 17456523 3975251
7 Locked 40.9 14224 15255
8 Locked 38.9 28150 16787
9 Locked 40.3 2478 16536
10 Locked 38.9 2937 16430
11 Locked 40.9 2857 15055
12 Locked 40.3 17351 16671
13 Locked 40.3 2195 17199
14 Locked 38.9 3778 17268
15 Locked 40.9 3061 14075
16 Locked 38.9 240243 15793
17 Locked 40.3 28776 14808
18 Locked 38.6 7451 16017
19 Locked 40.3 8726 7360
20 Locked 40.3 7203 10262
21 Locked 38.9 21167 16244
22 Locked 38.6 6321 11619
23 Locked 40.3 10948 6189


Upstream bonded channels
Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID
1 46200000 5.025 5120 64 qam 3
2 39400000 5.025 5120 64 qam 4
3 53700024 5.1 5120 64 qam 2
4 60300000 5.1 5120 32 qam 1

 

Upstream bonded channels
Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts
1 ATDMA 0 0 0 0
2 ATDMA 0 0 0 0
3 ATDMA 0 0 0 0
4 ATDMA 0 0 0 0


Network Log
Time Priority Description
27/10/2020 16:14:51 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 16:13:12 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 16:13:3 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 16:11:41 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:59:59 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:59:50 notice LAN login Success;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:31:1 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:30:48 critical No Ranging Response received - T3 time-out;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:25:11 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:22:52 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:12:8 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:12:7 critical No Ranging Response received - T3 time-out;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:10:21 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:10:20 Warning! Lost MDD Timeout;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:10:14 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:10:12 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:06:50 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:06:35 Warning! Lost MDD Timeout;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:06:25 Warning! RCS Partial Service;CM-MAC=xxxx;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;
27/10/2020 15:05:4 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xxxx:4b;CMTS-MAC=xxxx;CM-QOS=1.1;CM-VER=3.0;

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Alessandro Volta
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Re: M100 performance problem

Your downstream levels are too low and the upstream levels are too high.

Check that all the coax cables are seated correctly and are tight/secure, reboot the hub, then post the logs back here again.

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Re: M100 performance problem

Interesting - what would be the nominal range expected for VM ?  The downstreams are certainly well within the operating range for DOCSIS 3.0 although it's not my specialist area (I'm a networking architect by profession but typically work with IP and MPLS and optical systems) but if it's out of spec for VM and there is a pointer/link to expected values somewhere it would be highly useful to know.

I rebooted and checked the cables a few times when fitting the new hub3 at the weekend but have re-visited it again and interestingly on reboot for a short period it showed 5 upstream channels locked in before dropping back to 4.  The power levels, however, remain unchanged so if the signals are too low then the likely culprit for signal attenuation may well be the exterior junction box where the incoming cable and legacy phone copper cable were split out (the phone cables have long since entered disuse).

The signal levels on the downstream side are actually lower after checking and rebooting but I do notice that channel 4 on the upstream is now operating and 64QAM and not 32QAM which would potentially indicated it had fallen back the modulation due to noise.

I guess I'll just keep an ongoing eye on the levels and throughput for now and see if the problem continues to happen.

Thanks,

Jacqui

Downstream bonded channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

1259000000-140256 qam16
2251000000-2.538256 qam15
3267000000-1.540256 qam17
4275000000-2.740256 qam18
5283000000-2.538256 qam19
6291000000-1.240256 qam20
7299000000-1.440256 qam21
8307000000-3.238256 qam22
9315000000-2.438256 qam23
10323000000-1.440256 qam24
11347000000-2.740256 qam25
12355000000-2.738256 qam26
13363000000-1.540256 qam27
14371000000-338256 qam28
15379000000-3.438256 qam29
16387000000-2.938256 qam30
17395000000-1.940256 qam31
18403000000-2.938256 qam32
19411000000-3.740256 qam33
20419000000-3.238256 qam34
21427000000-2.240256 qam35
22435000000-3.239256 qam36
23443000000-4.738256 qam37
24451000000-3.238256 qam38



Downstream bonded channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1Locked40.900
2Locked38.900
3Locked40.300
4Locked40.300
5Locked38.6130
6Locked40.900
7Locked40.300
8Locked38.9130
9Locked38.910
10Locked40.300
11Locked40.360
12Locked38.900
13Locked40.300
14Locked38.900
15Locked38.930
16Locked38.6210
17Locked40.300
18Locked38.900
19Locked40.330
20Locked38.920
21Locked40.9150
22Locked39.840
23Locked38.670
24Locked38.680

 

Upstream bonded channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

1462000005.025512064 qam3
2394000005.025512064 qam4
3537000005.1512064 qam2
4603000005.1512064 qam1



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0000
3ATDMA0000
4ATDMA0000
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Re: M100 performance problem

Downstream levels need to be between -3 and +10 but as close to zero as possible ideally. 


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Re: M100 performance problem

A warm welcome to our Community Forum @Jacquigreen and sorry about the connection issues you're having. I've found your details using the information we have on here and can see that @gary_dexter is correct. I'm looking at the live details and your downstream is on the very low side and your upstream power levels for some channels are very high.

 

I've arranged for an engineer to take a look at your connection and you can find the details via your online account where you can re-arrange it if necessary.

 

Do let us know how it goes.

 

Thanks,

 

Lisa

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