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#55297 by drujaz
Tue May 11, 2010 12:31 pm
Hello All,

I am hoping for some assistance here. I currently have Comcast Cable internet with speed rated at 12Mbps (up) and 3Mbps (down).


Cable Modem -> ooma -> router -> multiple PCs (wired and wireless).

Every few days, my cable modem will go offline with logs stating:

"No Ranging Response received - T3 time-out"

the send signal keeps blinking and the online light shows the modem is offline. Calling Comcast support is useless as all they offer is to disconnect the coax cable and the power, wait 30 seconds, and then reconnect. If that fails, you are SOL and need a new modem.

I am noticing that if I disconnect the ethernet cable, and powercycle the cable modem with the steps above mentioned by Comcast Support, it will come back up and online.

I need to figure out what is causing it to go offline in the first place, and then what is interfering with it coming back online once it goes offline....

Thanks in advance.
#55300 by drujaz
Tue May 11, 2010 12:50 pm
Thanks for that lbmofo, but I have done every reset under the sun, including factory reset on the modem... Based on Comcast's recommendations, I had also replaced the modem and still the same problem occurs. I wouldn't doubt that something's going on on the Comcast side. I decided to go back to DSL since I have never really had any issues with DSL. I am hoping its not an ooma problem that will follow me to the DSL also.

One option was changing my config to connect the ooma behind the router instead of inbetween the modem and the router...
#55305 by drujaz
Tue May 11, 2010 1:11 pm
I had tested the line with's test app quite a few times and all numbers would be within acceptable parameters. The jitter was a bit of concern as it was normally above 4.2 but less then 5.0. QOS was always showing as above 65% (varies with each test).

I can upload the test results when I get home.
#55398 by drujaz
Wed May 12, 2010 7:49 pm
Here are my test results:

VoIP test statistics
Jitter: you --> server: 4.4 ms
Jitter: server --> you: 3.6 ms
Packet loss: you --> server: 0.0 %
Packet loss: server --> you: 0.0 %
Packet discards: 0.0 %
Packets out of order: 0.0 %
Estimated MOS score: 4.0

Speed test statistics
Download speed: 12322496 bps
Upload speed: 2951264 bps
Download quality of service: 90 %
Upload quality of service: 66 %
Download test type: socket
Upload test type: socket
Maximum TCP delay: 29 ms
Average download pause: 2 ms
Minimum round trip time to server: 30 ms
Average round trip time to server: 35 ms
Estimated download bandwidth: 22400000bps
Route concurrency: 1.8178135
Download TCP forced idle: 34 %
Maximum route speed: 17476000bps

and here is my modem information (MOTOROLA SB5101U):

Frequency: 723000000 Hz
Signal To Noise Ratio: 34.8 dB
Power Level: -3.8 dBmV

Channel ID: 3
Frequency: 30600000 Hz
Power: 43.2 dBmV

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