Basic Internet Connectivity And Modem Help

[fredhorch]

We are having the same issue here in Brunswick, Maine. Internet is almost unusable. Connection dropping every few minutes.  Seems to have gotten worse over the last week.

[EG]

What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1

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

[fredhorch]

My modem is at http://10.0.0.1

Downstream Channel Bonding Value

Index 1 2 3 4

Lock Status Locked Locked Locked Not locked

Frequency 692.998 MHz 698.999 MHz 705.001 MHz  

SNR 37.936 dB 37.636 dB 37.936 dB  

Power 6.457 dBmV 6.532 dBmV 6.015 dBmV  

Modulation 256 QAM 256 QAM 256 QAM

Upstream Channel Bonding Value

Index 1 2 3 4

Lock Status Locked Not locked Not locked Locked

Frequency 35800000 Hz     29400000 Hz

Symbol Rate 5120 KSym/sec     5120 KSym/sec

Power Level 37.7500 dBmV     37.7500 dBmV

Modulation 64QAM     64QAM

Channel ID 5     4

[fredhorch]

Here is an excerpt from the logs:

Lost MDD Timeout;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:28:01 warning SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:27:57 critical Lost MDD Timeout;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:27:31 warning SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:27:26 critical Lost MDD Timeout;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:27:03 warning SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:26:56 critical No Ranging Response received - T3 time-out;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:26:27 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:26:19 critical Lost MDD Timeout;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:25:37 warning SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:25:33 critical Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:25:25 critical Lost MDD Timeout;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:24:27 warning SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:24:22 critical No Ranging Response received - T3 time-out;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 07:23:43 critical

[EG]

The signal stats at the moment in time were in spec. That address looks to be one for a combo modem / gateway device (perhaps an SMC ?) If it is, is it only wireless connections that drop or do hard wired ethernet connections to it drop as well ?

[fredhorch]

Everything drops.

[fredhorch]

The log is one hour off (e.g. it's now 4:16 pm but the log date stamps show 15:16) and full of warnings and critical error messages.

Sample:

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 15:11:38 critical

No Ranging Response received - T3 time-out;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 15:09:35 critical

Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 14:16:14 critical

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b8:9b:c9:9c:af:70;CMTS-MAC=1c:df:0f:02:2d:3a;CM-QOS=1.1;CM-VER=3.0; 2012/09/18 12:32:48 critical

[EG]

Is it an SMC ? Exact make and model number would be more helpful to both you and I rather than a "one liner" answer ? This may be a firmware problem that we have been seeing here as of late. It may also be a hardware defect. These SMC's are basically junky devices.

If wired connections "drop" as well, then this may indeed be an RF signal / connection quality issue on the Comcast side even though the stats that can be displayed by the modem are in spec. There is more to the story.

There are two additional signal stats which can't be read at the modem level. They can only be read from their end by them polling the CMTS (Cable Modem Termination System) at the local headend facility.

They are the 'Upstream Receive Power Level' and the 'Upstream uSNR' (upstream Signal To Noise Ratio). Both of these are as equally important in diagnosing connectivity issues as are the modem's stats.

You can call in and ask what these figures are. The Upstream Receive Power Level should fall within the range of -10dB to +10dB with 0dB being in the middle and perfect.

The Upstream SNR should be least 30dB, and the higher it is the better. You could have a noise ingress issue in the upstream channel/s (path).

Don't worry about the time. It doesn't affect performance. Modems don't adjust for daylight savings / standard time.