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Labrajaws
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High Latency question on M100

I have been running Broadband Quality Monitor for a few days and have noticed random spikes in latency. Some occur around 3am when the connection is not being used (as far as I know!).

Can anyone explain why this would happen?

Capture.JPG

https://www.thinkbroadband.com/broadband/monitoring/quality/share/44989a31ad689af7b7a26ea3295774007c...

Note: The red column was a known Broadband issue in my area this morning.

Thanks

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DJ_Shadow1966
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Re: High Latency question on M100

Hello

Could have been that the network was generally busy in your area, what symptoms are you experiencing, when I have checked mine from last night this AM I can see spikes at pretty much the same time.

Mike

I dont work for VirginMedia all opinions are my own.
39 years in IT.
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Andruser
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Re: High Latency question on M100

I can't explain why the random spikes occur, although they seem to occur for most users, but what I can say is: Yuck! Your BQM is truly awful, not only is the latency spiking atrocious, but if you enlarge the graphic you'll see some evidence of minor but repeated packet loss between 12pm and 9pm.  The various communication protocols and error correction of the hub will sort out the dropped packets, but even at very, very low levels packet loss can interrupt streaming and connection speed.

Compare your BQM to mine below, for a Hub 3 on a 200 Mbps connection.  Normally mine will show about three spikes per 24 hours at random, and up to about 100ms on those spikes - the chart below just happened to be an exceptionally "clean" day, but it does show a Hub 3 operating at its best. 

What hub do you have, and if it is a Hub 3, what firmware is it running?  Potentially a Hub 3 running latest firmware might fix this, but if you already have one, then I think your connection may have a problem with SNR, power levels or error performance.  The good news is that these are usually easily fixed if they can be diagnosed.

My Broadband Ping - VM number 2

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Labrajaws
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Re: High Latency question on M100

Thanks for the replies. I have the Hub 3 with latest firmware I think (only had Virgin for a few weeks now). Due to the useless wifi coverage, I have the 2G and 5G hub wifi channels disabled and a wired connection to a BT Whole Home 3 disc mesh system, which gives good coverage all over the house.

I have been advised to get a 'proper' router and use the Hub in Modem mode, but am reluctant to do this as my only real issue is with a Ring Elite Stick Up Cam that is powered/connected by PoE/Ethernet. I often find the recorded videos have clipped sound and stall for several seconds in some recordings. Otherwise the kids are happy when gaming on the XBox or PC  (Fortnite/Roblox/Minecraft so mainly low bandwidth requirement games) in different rooms and at the same time and we don't have any issues with Streaming Netflix, Youtube etc in HD.

The Ring camera issue was not present when we had Talk Talk Fibre (@35/10 DL/UL) so I don't think it's a hardware issue or a fault with the Ring servers.

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Andruser
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Re: High Latency question on M100

Fab detail, that really helps.  We can rule out wifi as a cause or concern.  As an aside if the Hub 3/BT disks are working well don't change them - the argument that the Hub 3 router isn't up to much is true, but that is academic if the setup works for you.  IoT devices like cameras and PoE kit are notorious for being picky, whilst often restricting themselves to crummy 2.4 GHz connections - a new router might fix that, but I wouldn't personally recommend a £200 router as a guaranteed fix.  If you were buying a router anyway, buying a good one makes sense, but when it comes to tech advice, it is always worth remembering the well proven equation that blokes + technology = (anorak talk)^2

I suggest we have a look and see what your hub status is.  As a start, connect to the hub 3, don't log in, just click Check router status and post the upstream, downstream and logs tabs here.  That'll show if there's an obvious SNR or power issue.  Also, log in to the hub, and under Advanced settings>Tools>Network status have a look at the pre-RS and Post RS errors.  If the pre-RS figures are single to triple digit there's probably not much to worry about, and ideally you'd have all post-RS error values at zero, or at least low double digit numbers. As a comparison, my Hub 3 is showing pre-RS numbers in the range 3-25, and post RS of zero on all channels.  RS refers to Reed Solomon error correction, and this is an algorithm that enables certain faulty data sets to be successfully reconstructed even if some bits are missing.  It was this that enabled the optical disk, and without RS CDs would never have worked.  For the odd bit missing here and there, RS will fix it without problem, but as the number of errors rise, the time taken for error correction may become significant, but usually the number of uncorrectable errors rises - the internet & DOCSIS communications protocols then re-request the faulty data, and that causes slower speeds and can mess up streaming.  If there's loads of errors, then post the numbers here as well.

Fingers crossed for a nice obvious problem, because sometimes there isn't an obvious solution!

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Labrajaws
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Re: High Latency question on M100

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Labrajaws
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Re: High Latency question on M100

Network Log
Time Priority Description
04/10/2019 15:10:56 critical Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
07/10/2019 09:05:13 critical No Ranging Response received - T3 time-out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
08/10/2019 10:55:50 Error DHCP RENEW sent - No response for IPv4;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
08/10/2019 13:10:23 critical No Ranging Response received - T3 time-out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
08/10/2019 23:26:22 Error DHCP RENEW sent - No response for IPv4;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
09/10/2019 11:56:59 Error DHCP REBIND WARNING - Field invalid in response;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
10/10/2019 06:23:36 critical No Ranging Response received - T3 time-out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
13/10/2019 08:55:59 Error DHCP RENEW sent - No response for IPv4;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
14/10/2019 10:17:36 Error DHCP REBIND WARNING - Field invalid in response;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
14/10/2019 13:57:30 critical No Ranging Response received - T3 time-out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 09:14:30 Warning! RCS Partial Service;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 09:14:33 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 09:14:34 Warning! RCS Partial Service;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 09:14:34 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 09:14:38 Warning! Lost MDD Timeout;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 09:16:53 critical Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 10:07:41 Warning! Lost MDD Timeout;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 10:07:54 critical No Ranging Response received - T3 time-out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 10:07:59 Warning! Lost MDD Timeout;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;
15/10/2019 10:12:43 critical No Ranging Response received - T3 time-out;CM-MAC=XX.XX.XX.XX.XX.XX;CMTS-MAC=XX.XX.XX.XX.XX.XX;CM-QOS=1.1;CM-VER=3.0;

 

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Andruser
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Re: High Latency question on M100

Power levels and SNR appear to be fine on both upstream and downstream, but there may be a problem with errors.  Although the pre-RS errors are ones that have been caught and corrected, it looks to me as though there's far too many for a health connection across all channels, and on channel 1 there's a significant number of post-RS errors - that is to say, uncorrected errors, and these will cause latency and possibly speed problems.  The latency issues are probably linked, but this error count is collected since the hub was last rebooted, so that could be over a very short period, or over a very long period.  If you know when the hub was last rebooted then that'd be helpful, if not I suggest you reboot your hub to reset the error counters, let it run for a couple of days, see if these are building up again.

There's not much you can do in the meanwhile other than check to make sure that the cable between the hub and the wall is in good condition and securely attached, so this is where your best bet is to wait for the mods to pick this up and see if they can comment, or arrange a field technician to take a look.  You could try calling the technical support line, personally I wouldn't bother on the basis that I don't expect they'd understand the problem.

Possible causes are many, and could include a faulty hub (yours, or even somebody else's on the same circuit), it could be due to interference within VM's equipment, or configuration or physical connection issues - all should be resolvable, but you'll be reliant upon the field tech knowing their stuff.  Many are very good, some just swap the hub, cross their fingers and get back in the van.

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DarkBahamut
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Re: High Latency question on M100

The biggest surprise for me is that someone thinks that BQM is "truly awful"! Sure, it's a tiny bit ugly, but congested nodes can look much much worse than that.

To the matter at hand, I would say from the posted logs the BQM is almost certainly just area loading. Your channels are shared and all data on them hits your hub (this is why you get spikes even if you don't use your connection). The stats are spot on and while there are some RS errors, the logs also show loss a period where you had loss of sync, so this would easily explain the RS error counts. Remember, figures like '50000' look big, but that's a few seconds worth of data, so even a momentary blip (that loss of sync) can cause that.

IMHO, I don't think there's actually going to be any issues here. Error counts easily explained by momentary loss of connection, stats otherwise spot on and the BQM completely inline with some minor area load, but I would be surprised if the node is anywhere near congested enough for attention from the spikes shown.

What do you peak time speed tests look like?

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Forum Team (Retired) Louis_R
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Re: High Latency question on M100

Hi Labrajaws,

 

Thank you very much for your post. We are sorry to hear that you have been experiencing these issues and we would certainly like to assist further from our side. This will require a private message in order to access the account as well as asking some security questions. We will follow up right away.

 

Many thanks,

 

Louis

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