Comcast XFINITY → [Connectivity] Question on T3 Timeouts

I have had major Internet and Cable TV outages in the last few weeks so I called Comcast and after replacing everything in the house, and I mean everything, cables, connectors, splitters, and Modem, Comcast rolled 3 trucks to my neighborhood and found they had to Balance the "node" as the Lineman stated the signals were so high it raised the noise level to the point it was corrupting signals in both directions. The balancing has corrected all problems but one.

What I am now left with is T3 errors on the Modem. I wrote a script to monitor the modem status page for a channel change, and if changed, capture the most recent T3 error time stamp from the modem log. Every download channel change results in a T3 error and I simultaneously run Fping with time stamps and capture Internet outages. I have a 100% match of 3 to 5 Internet outages an hour of 5 to 12 seconds during the day, peaks at 8 to 9 PM, and non-existent from 1 AM to about 9 AM, so they must be load balancing related.

Unfortunately, these presumed "load balancing" outages break my VOIP Phone, VPN to work, and occasionally my wife's Outlook get set to Offline operation, streaming sometimes stops, and it is very frustrating as the 5 to 12 seconds usually results in much longer outage to VOIP and VPN to allow recovery. I upgraded to a SB6121 DOCSIS 3.0 modem assuming it would fix this issue, but no luck. All signals on my end are rock solid and right in the "sweet spot" as recommended by Comcast.

A few questions, If I get Comcast back out here to fix the T3 errors, will this fix my 5 to 12 second Internet outages, or are these outages by poor design of Load Balancing. Should I be pressing to get DOCSIS 3.0 channel bonding working in my neighborhood, as it is currently not available? I have trouble believing it is DOCSIS standard to interrupt VOIP, VPNs, Streaming, etc. for load balancing in such a crude method.

I have posted in the Comcast Direct forum but so far no response.

I would appreciate any ideas the forum members can offer.

Odd. Switching to a D3 modem should prevent the channel hopping, which should eliminate the cutouts (I did the same a few years ago as I also work from home.)

Are the downstream channels changing on the D3 modem, or are the staying the same? Posting your signal levels may help, too.

Can you post a screen shot of your signals and log pages?
Have you called in and asked what your upstream SNR is?
I wouldn't say the outages are nessesarily load balacing problems, ToD based occurances can be heat related or due to electrical or other interferance, so I would think maintaince, upgrades, failing equipment, extreme heat should be considered.
Even load balancing SHOULD leave the majority of users on the initial channel while moving a small percentage to another channel, if this is not happening then CC needs to troubleshoot that process.

Thank you for your comments. First, my area is a DOCSIS 2.0 area as there are 2 downstream channels, 9 and 10, and 1 upstream channel, channel 3 and there is no channel bonding.

Signal levels without any attenuation is upstream 34 and downstream are 10 db with SNR of 38. All signals are solid on both channels. I have inserted an attenuator to reduce the signals to the Comcast recommended "Sweet spot" and they are currently:

Channel ID 10
Frequency 537000000 Hz
Signal to Noise Ratio 38 dB
Downstream Modulation QAM256
Power Level 3 dBmV

Channel ID 3
Frequency 20000000 Hz
Ranging Service ID 8215
Symbol Rate 2.560 Msym/sec
Power Level 43 dBmV
Upstream Modulation [3] QPSK [2] 16QAM

I have not called to get my upstream uSNR but will.

Log since modem reset yesterday: NOTE: new T3 timeouts do not create a new log entry, but simply update the time stamp on the latest T3 log entry.

Jul 05 2012 13:40:07 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:6e:2f:46;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

Jan 01 1970 00:00:12 6-Notice Cable Modem Reboot from GUI/Configuration page ;CM-MAC=a4:7a:a4:6e:2f:46;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

My script output for thus far today (NOTE: Log time is EST, - 1 hour)

Microsoft (R) Windows Script Host Version 5.8
Copyright (C) Microsoft Corporation. All rights reserved.

Channel 10 7/5/2012 8:15:02 AM, T3 Error Log Time= Jul 05 2012 07:15:04
Channel 9 7/5/2012 10:19:59 AM, T3 Error Log Time= Jul 05 2012 09:20:03
Channel 10 7/5/2012 10:50:03 AM, T3 Error Log Time= Jul 05 2012 09:50:06
Channel 9 7/5/2012 11:20:03 AM, T3 Error Log Time= Jul 05 2012 10:20:03
Channel 10 7/5/2012 11:45:04 AM, T3 Error Log Time= Jul 05 2012 10:45:05
Channel 9 7/5/2012 12:00:02 PM, T3 Error Log Time= Jul 05 2012 11:00:04
Channel 10 7/5/2012 12:10:03 PM, T3 Error Log Time= Jul 05 2012 11:10:05
Channel 9 7/5/2012 12:25:02 PM, T3 Error Log Time= Jul 05 2012 11:10:05
Channel 10 7/5/2012 12:50:00 PM, T3 Error Log Time= Jul 05 2012 11:50:04
Channel 9 7/5/2012 1:00:01 PM, T3 Error Log Time= Jul 05 2012 12:00:04
Channel 10 7/5/2012 1:25:04 PM, T3 Error Log Time= Jul 05 2012 12:25:04

Every Channel Change is associated with a 5 to 12 second ping failure, reflecting the modem outage.

Again, thanks for your comments.

Odd. I thought Comcast was pretty much 100% D3 by now.

Until they get channel bonding, you won't be able to do much about the channel hopping. That's what is causing most of your issues.

The T3's could be due to the changes they made when fixing things earlier. Maybe a bad connection somewhere?

Ok I might be a little worried at those values, please recognize the attenuators only change the apparent value and don't improve signal quality, so it is possible that comcast should further adjust the plant/tap value.
You should not have to add any attenuation yourself, if needed CC should provide top quality devices.
also T3's are often associated with upstream noise and your fairly low "native" output means an upstream SNR check/montoring is vital.
Intermittents are they most diffcult to troubleshoot, but your logging has already narrowed the time window and you should continue to look for patterns. for insance it appears to be happening at exact multiples of 5 minute intervals, some thing hard to blame on sunshine patterns on an amp, more like a timed motor or charger type load or some network signal or process?
I think further tech visits are in your future.

That's for the upstream / transmit / return power. They basically only make that figure look prettier. They can and do help to lower the actual forward power hitting the modem which can result in an actual performance improvement if need be, for example, if the modem's front end receiver is being saturated.

It is lowering the value, but ANY device inserted increases the possiblity of noise, and acustomer purchased item may not meet the quality standard or specs needed. also when you add a deivce like that if they poll local modems and adjust the plant to fit the average, that average may no longer be the best profile for an unaltered drop.
It really is best to let the techs adjust outside values as close as possible and provide any need amps etc. Self help should only be a last desperate step.

Can't argue that tshirt !!