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CMTS Ranging Failures with Loss of Internet and Voice Services

New Poster

CMTS Ranging Failures with Loss of Internet and Voice Services

Recently, I've been losing my Internet and phone service for a brief period of time, about 15 to 20 minutes each time.  Interestingly, this happens around same time of day each time, between 10:00 AM and 10:30 AM MT.

 

During each outage, my firewall device (Linksys LRT214) is unable to obtain in IP address assignment from the Comcast DHCP server.  This points to the issue being on the Comcast side and not something in-house.

 

When I connect to my cable modem (Netgear CM1150V) and check the Event Log, I see this sequence of events starting at the time I lost my Intenet and voice services:

 

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:d2:94:5a:53:90;CMTS-MAC=00:01:5c:71:60:7a;CM-QOS=1.1;CM-VER=3.1;

 

Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:d2:94:5a:53:90;CMTS-MAC=00:01:5c:71:60:7a;CM-QOS=1.1;CM-VER=3.1;

 

16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=78:d2:94:5a:53:90;CMTS-MAC=00:01:5c:71:60:7a;CM-QOS=1.1;CM-VER=3.1;

 

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:d2:94:5a:53:90;CMTS-MAC=00:01:5c:71:60:7a;CM-QOS=1.1;CM-VER=3.1;

 

My modem is ranging with the Comcast CMTS and that's failing.

 

FYI, my upstream channel 2 dBmV is 44.3, which is within the normal range of 25-54 dBmV.

 

Has anyone else experienced this?  If so, what was the resolution?

 

Thanks,

 

Bill...

 

Expert

Re: CMTS Ranging Failures with Loss of Internet and Voice Services

Please also post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.




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New Poster

Re: CMTS Ranging Failures with Loss of Internet and Voice Services

My downstream power levels are in the range of -5.6 to -3.5 dBmV.

 

My downtream SNRs are in the range of 39.3 to 40.7 dB.

 

My upstream power levels are in the range of 43.0 to 44.3 dBmV.

 

Expert

Re: CMTS Ranging Failures with Loss of Internet and Voice Services

Hmmmm. Those were o/k at that snapshot in time. Perhaps something intermittent is going on. The error logs confirm a handshake with the CMTS issue is present.



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New Poster

Re: CMTS Ranging Failures with Loss of Internet and Voice Services

Yes, it is an intermittent failure.  But one that occurs at around the same time of day when it does happen.  From what I could determine, the power levels, both up and down, all seem OK.  From what I see in the modem log, it looks like the CMTS went on a break.

 

The first time this problem occurred, I power cycled my modem thinking it had gotten itself into some confused state.  But when it came back up, I still couldn't get an IP address from the Comcast DHCP server.  Then, a few minutes later, it all came back to life and was fine until the next failure.

Expert

Re: CMTS Ranging Failures with Loss of Internet and Voice Services

Perhaps there is intermittent noise ingress into the line(s) somewhere. Maybe you should get a tech out to investigate.



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