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zerebubuth
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Increased latency and packet loss after upgrade to SH3

Hi,

After many years of good service, with average pings in the 23-25ms range and packet loss generally under 3%, our old SuperHub finally keeled over. Not sure what the problem was - just wouldn't turn on, even with a different (known working) power supply. We got a replacement SH3, but the average pings are now in the 35-45ms range and packet loss around 8-10%. Needless to say, that kind of packet loss is causing a lot of problems with iPlayer, Skype and other streaming services.

I see that there are a lot of other threads blaming the SH3's Puma chipset for this, but there seems to be very little that can be done about it?

I've included the network details below, in case it's actually network-related and the timing is just a coincidence (or perhaps Puma is more sensitive than whatever was in the old SuperHub). I don't understand the details, and Googling the "Lost MDD Timeout" / "RCS Partial Service" messages has left me none the wiser. Please let me know if there's anything that can be done to improve things.

Many thanks!

Modem status

Cable Modem StatusItem Status Comments

Acquired Downstream Channel(Hz)
299000000
Locked
Ranged Upstream Channel(Hz)
39400000
Locked
Provisioning State
Online
 

Downstream

Downstream bonded channelsChannel Frequency(Hz) Power(dBmV) SNR(dB) Modulation Channel ID

12990000002.240.3256 qam21
23230000002.740.3256 qam24
3315000000240.3256 qam23
43070000002.240.3256 qam22
52910000000.940.3256 qam20
62830000002.740.3256 qam19
72750000001.440.3256 qam18
82670000002.440.3256 qam17
92590000002.940.3256 qam16
10251000000240.9256 qam15
112430000003.740.3256 qam14
12235000000240.3256 qam13
132270000002.532.5256 qam12
14219000000226256 qam11
152110000001.940.3256 qam10
162030000003.240.3256 qam9
171950000002.738.9256 qam8
181870000005.140.3256 qam7
191790000005.640.3256 qam6
201710000005.340.3256 qam5
211630000006.940.3256 qam4
221550000005.640.3256 qam3
231470000007.140.9256 qam2
24139000000738.9256 qam1

Upstream

Upstream bonded channelsChannel ID Frequency(Hz) Mode Power(dBmV) Modulation Channel Bandwidth(Hz) Symbol Rate (ksps)

239400000ATDMA41.316 qam64000005120
425800000ATDMA41.316 qam64000005120

Configuration

Operational ConfigurationGeneral Configuration Value

Network access
Enabled
Maximum Number of CPEs
1
Baseline Privacy
Enabled
Docsis Mode
Docsis30
Config file
V0d8310cb0396200.cm
Primary Downstream Service Flow
SFID148007
Max Traffic Rate80500000
Primary Upstream Service Flow
SFID148006
Max Traffic Rate5250000

Network Log

Network LogDate And Time Error Number Event Description

2018-03-14 09:02:27.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:02:29.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:07:44.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:07:44.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:07:54.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:07:56.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:19:55.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:19:59.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:20:40.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:20:44.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:37:56.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:37:56.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:39:51.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:39:52.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:52:29.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:52:29.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:55:14.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:55:14.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:56:09.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-14 09:56:09.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
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jb66
Alessandro Volta
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Message 2 of 8
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Helpful Answer

Re: Increased latency and packet loss after upgrade to SH3

You have a loose fitting or a damaged cable

 

14219000000226256 qam11
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zerebubuth
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Message 3 of 8
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Re: Increased latency and packet loss after upgrade to SH3

Thanks! I checked the cable fitting and it seems tight as far as I can tell. I guess the next thing would be to get someone from Virgin out to do more thorough diagnostics to see where the cable/connector is bad.

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Forum Team
Forum Team
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Re: Increased latency and packet loss after upgrade to SH3

Hi zerebubuth,

I am sorry about this. Tests of your connection from here aren't looking too bad, only a couple of T3 timeouts over the past few days and slightly low modem SNR on a couple of the downstream channels.

However, if you are still getting MDD timeouts, and there has been no improvement in your connection since posting, I should like to arrange for an engineer to visit. Please reply to my PM (purple envelope icon, top right of page) and I shall schedule an appointment for you.

Kind regards,


Jen
Forum Team



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zerebubuth
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Re: Increased latency and packet loss after upgrade to SH3

Hi Jen_A,

Thanks very much! I've been waiting to see if there's any improvement and, sadly, there hasn't been. I'm still seeing messages about MDD timeouts in the log, and they still being generated even after a reboot. E.g:

2018-03-26 08:17:33.0084000700RCS Partial Service;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;
2018-03-26 08:18:02.0084020200Lost MDD Timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.0;

 

Latencies remain higher than with the previous router, and packet loss is still a problem (ignore the gap / 100% bit in the graphs - that's for the period between the old router failing and the new one being installed). Watching BBC iPlayer last night, we generally had at least 3 or 4 periods of buffering during each programme, when it used to be rare to have any at all.

Screenshot from 2018-03-26 09-24-41.pngLatency (ms) over time.

Screenshot from 2018-03-26 09-26-42.pngPacket loss (%) over time.

As far as I can tell, there's nothing wrong with the cable connection to the router, so I'll request a someone to come check whether there's anything wrong with the cable from there to the street.

Many thanks!

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Re: Increased latency and packet loss after upgrade to SH3

Hi zerebubuth,

I'm still only seeing the low downstream modem SNR - all other tests are returned with no issues detected on the network. I'm not convinced the modem SNR on only a couple of downstream channels is responsible for what you describe, but it makes sense to get an engineer out to investigate.

Please see my PM for details of the appointment I've scheduled. And let me know how your connection is following the visit.

All the best,


Jen
Forum Team



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jb66
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Re: Increased latency and packet loss after upgrade to SH3

Low snr on one frequency causes the hub to reboot in my experiance

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zerebubuth
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Re: Increased latency and packet loss after upgrade to SH3

Exactly as jb66 predicted, the problem turned out to be a bad connection. An engineer visited yesterday, located the problem and replaced the connector, and the packet loss average has been <1% since. I haven't seen any buffering while watching iPlayer, and there haven't been any more messages about "RCS partial service". The latency has dropped a little from 35-45ms down to 27-30ms, which isn't back to the 20-25ms that we used to get before we installed the SH3, but it's low enough that it doesn't seem to impact Skype or Hangouts video calls in a noticeable way.

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