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Packet Loss

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Frequent Visitor

Packet Loss

I've been dealing with an INTERMITTENT issue regarding loss of connectivity. It will be fine for a few days, and then come back on and off randomly for a few days. Sometimes it is as bad as 30% packet loss. I was attempting to explain this to a support tech who was insisting it was a faulty cable modem (it is a known-good modem), and wanted to send a tech to replace it.

 

The support tech "Shubham" then simply disconnected from the support session when I showed him that the issue with packet loss on my connection appears on COMCAST's end, not my own end.

 

I have MTR logs that seem to show the packet loss was coming from Comcast's device at IP 96.120.28.129.

 

Here are some screen shots of my MTR results and my cable modem signals:
MTR: https://imgur.com/BNE4do9 
Modem: https://imgur.com/OCWAsUm 

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Expert

Re: Packet Loss

The signal stats that you posted are o/k. Are there any more downstream channels being shown ? If so, please post the balance as only 11 through 18 are visible in your pic.



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Frequent Visitor

Re: Packet Loss

I have an SB6141, which is an 8x4 channel modem... Not the quickest modem, but it's fast enough for the plan I am on. But looking at it now, it is different: https://imgur.com/T1e0gfShttps://imgur.com/aLEHqAg https://imgur.com/T1e0gfShttps://imgur.com/T1e0gfS

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Expert

Re: Packet Loss

O/k thanks for that info. Eight channels are indeed being shown, it's just that they are not labeled as being one thru eight. The frequencies of the channels, however, are different (the labeling doesn't matter) shows that the modem has now locked on to a different set of channels. And these channel's signal stat numbers are also o/k.

 

FWIW, packet loss can also be being caused by a local capacity / congestion problem and also by upstream / return path noise ingress.

 

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

 

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !



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Official Employee

Re: Packet Loss

Good evening, frosty0024. Thank you for awaiting my reply. It's frustrating to hear about your connectivity trouble. I would like to take a look at a few diagnostics on this end to see if we can narrow down the cause of the issue. Please send me a PM with your first and last name and we will continue from there. 

 

To send a private message, please click my name "ComcastMorgan" then select "Send a Message" on the right side.

 

I will meet you there. Thank you!

 

 


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Frequent Visitor

Re: Packet Loss

I sent Morgan a PM and got no response.

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Official Employee

Re: Packet Loss

I  am still with you. Please get back with me via PM. 


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Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
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Frequent Visitor

Re: Packet Loss

A bunch of my neighbors are now posting on the neighborhood Facebook group about these problems.

 

https://imgur.com/7bs5IVv