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oliverwoodings
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Intermittent packet loss/total connection dropout, high latency

Hi,

I recently signed up to virgin broadband at our new property (on the 8th Jan). Ever since getting set up, I have been experiencing intermittent packet loss/high latency/complete dropouts. These occur every few minutes and is making it very hard to do my job. I have reseated all cables multiple times, restarted the modem to no avail. I believe this issue is outside of my home for several reasons:

1. Ping from inside out shows latency spikes and total dropouts, like so:
Screenshot 2021-01-19 at 16.17.40.png

2. Monitoring from ThinkBroadband shows packet loss (please ignore the total outages today, the power was off to the house):

b03fda6fd13a7fa4ccaeda1cdc4eb1e181542594-19-01-2021.png

3. Router status page shows high numbers of downstream errors (see stats dump below)

4. Router network log shows lots of 'critical SYNC Timing Synchronization failure - Loss of Sync' (see log dump below)

 

From looking at the forum, it seems like this is most likely caused by congestion or a configuration issue on the street, and that an engineer probably needs to come out?

Thanks,

 

Oli

oliverwoodings
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Re: Intermittent packet loss/total connection dropout, high latency

Here is the status dump:

Cable Modem StatusItem Status Comments

Acquired Downstream Channel (Hz)
139000000
Locked
Ranged Upstream Channel (Hz)
32600181
Locked
Provisioning State
Online

 

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

1139000000-2.435256 qam1
2147000000-235256 qam2
3155000000-2.235256 qam3
4163000000-1.935256 qam4
5171000000-1.735256 qam5
6179000000-1.735256 qam6
7187000000-1.535256 qam7
8195000000-1.535256 qam8
9203000000-1.535256 qam9
10211000000-1.735256 qam10
11219000000-1.235256 qam11
12227000000-0.935256 qam12
13235000000-0.735256 qam13
14243000000-0.736256 qam14
15251000000-0.536256 qam15
16259000000-0.236256 qam16
17267000000-0.436256 qam17
18275000000-0.436256 qam18
19283000000036256 qam19
202910000000.236256 qam20
21299000000036256 qam21
223070000000.236256 qam22
233150000000.936256 qam23
24323000000136256 qam24



Downstream bonded channels

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

1Locked35480314721866
2Locked35.724626510243
3Locked35.748358633923
4Locked35.5569966214486
5Locked35.73309157
6Locked35.52994135
7Locked35.53110110
8Locked35.7386499
9Locked35.5174317
10Locked35.712797
11Locked35.58030
12Locked35.575610
13Locked35.74790
14Locked36.31440
15Locked36.61180
16Locked36.6830
17Locked36.61360
18Locked36.3870
19Locked36.6240
20Locked36.3210
21Locked36.3160
22Locked36.6110
23Locked36.3210
24Locked36.3190

 

Upstream bonded channels

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

13260018152512016 qam5
23940023352512016 qam4
34620034052512016 qam3
45370021051512032 qam2



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0040
2ATDMA0030
3ATDMA0020
4ATDMA0000

 

 

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oliverwoodings
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Re: Intermittent packet loss/total connection dropout, high latency

General Configuration

Network access
Allowed
Maximum Number of CPEs
1
Baseline Privacy
Enabled
DOCSIS Mode
Docsis30
Config file
cmreg-vmdg505-bbt062-b.cm



Primary Downstream Service Flow

SFID2607772
Max Traffic Rate402500089
Max Traffic Burst42600
Min Traffic Rate0



Primary Upstream Service Flow

SFID2607771
Max Traffic Rate38500089
Max Traffic Burst42600
Min Traffic Rate0
Max Concatenated Burst42600
Scheduling TypeBestEffort

 

 

Network Log

Time Priority Description

19/01/2021 16:24:47criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 16:16:23criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 15:57:7criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 14:53:33Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 14:43:32criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 14:43:7Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 14:34:28criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:31:51criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:31:27criticalUnicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:31:27criticalRanging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:25:3criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:24:39criticalUnicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:24:39criticalRanging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:18:15criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:17:51criticalUnicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:17:51criticalRanging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:11:26criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:11:2criticalUnicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:11:2criticalRanging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/01/2021 08:04:38criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

 

 

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hughp60
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Re: Intermittent packet loss/total connection dropout, high latency

Interesting post, I suspect I am having the same issue, which has been going back a week or so now. I have only run download speedtests on all computers and mobiles, not the detailed analysis you have done, but the speeds are very intermittent, varying from no connection at all, up to 30mbps, but averaging around 1-5mbps. Reassuring to learn that it is most likely a Virgin network issue not within the house. We have an engineer coming Friday, but hopefully Virgin will look at the network issue you have flagged before then.
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carl_pearce
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Re: Intermittent packet loss/total connection dropout, high latency


@oliverwoodings wrote:

Here is the status dump:

Cable Modem StatusItem Status Comments

Acquired Downstream Channel (Hz)
139000000
Locked
Ranged Upstream Channel (Hz)
32600181
Locked
Provisioning State
Online

 

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

1139000000-2.435256 qam1
2147000000-235256 qam2
3155000000-2.235256 qam3
4163000000-1.935256 qam4
5171000000-1.735256 qam5
6179000000-1.735256 qam6
7187000000-1.535256 qam7
8195000000-1.535256 qam8
9203000000-1.535256 qam9
10211000000-1.735256 qam10
11219000000-1.235256 qam11
12227000000-0.935256 qam12
13235000000-0.735256 qam13
14243000000-0.736256 qam14
15251000000-0.536256 qam15
16259000000-0.236256 qam16
17267000000-0.436256 qam17
18275000000-0.436256 qam18
19283000000036256 qam19
202910000000.236256 qam20
21299000000036256 qam21
223070000000.236256 qam22
233150000000.936256 qam23
24323000000136256 qam24



Downstream bonded channels

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

1Locked35480314721866
2Locked35.724626510243
3Locked35.748358633923
4Locked35.5569966214486
5Locked35.73309157
6Locked35.52994135
7Locked35.53110110
8Locked35.7386499
9Locked35.5174317
10Locked35.712797
11Locked35.58030
12Locked35.575610
13Locked35.74790
14Locked36.31440
15Locked36.61180
16Locked36.6830
17Locked36.61360
18Locked36.3870
19Locked36.6240
20Locked36.3210
21Locked36.3160
22Locked36.6110
23Locked36.3210
24Locked36.3190

 

Upstream bonded channels

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

13260018152512016 qam5
23940023352512016 qam4
34620034052512016 qam3
45370021051512032 qam2



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0040
2ATDMA0030
3ATDMA0020
4ATDMA0000

 

 


Based on the highlighted values, and your network log, you appear to have a SNR issue.

Maybe a local area outage?

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carl_pearce
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Re: Intermittent packet loss/total connection dropout, high latency


@hughp60 wrote:
Interesting post, I suspect I am having the same issue, which has been going back a week or so now. I have only run download speedtests on all computers and mobiles, not the detailed analysis you have done, but the speeds are very intermittent, varying from no connection at all, up to 30mbps, but averaging around 1-5mbps. Reassuring to learn that it is most likely a Virgin network issue not within the house. We have an engineer coming Friday, but hopefully Virgin will look at the network issue you have flagged before then.

You can't assume you have the same issue.

You need to create your own thread, with HUB stats and a BQM to be sure.

oliverwoodings
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Re: Intermittent packet loss/total connection dropout, high latency

Thanks for the reply! There are no known outages in my area and this has been happening for 10 days now. Would you mind explaining what an SNR issue is please?

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carl_pearce
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Re: Intermittent packet loss/total connection dropout, high latency


@oliverwoodings wrote:

Thanks for the reply! There are no known outages in my area and this has been happening for 10 days now. Would you mind explaining what an SNR issue is please?


SNR = Signal to Noise Ratio.

If there is too much noise (Interference) it can cause problems with your connection.

High power levels can be the cause, however there are several other reasons.

Only VM can look into this for you.

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hughp60
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Re: Intermittent packet loss/total connection dropout, high latency

Thanks for the quick reply, I think I have found out how to get the hub stats and have started running a BQM, I’ll upload that to a new thread when I have got a full day’s data. The graph from midnight indicates significant dropped packets and high latency but will leave that to the community to interpret effectively. Thanks again for the advice, it’s been an interesting few hours.
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oliverwoodings
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Re: Intermittent packet loss/total connection dropout, high latency

@Chris_W1 I wonder if you might be able to help with this please? If i go on my account and do a test on my line, it puts up a vague message about there potentially being issues in my area, but it has no information about resolution. I currently cannot do my job because the internet connection is so poor.

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