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user_5w7r31
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Friday, December 15th, 2023 4:06 PM

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SYNC Timing Synchronization failure errors on Motorola MB7621

I've had a few Internet drops in the middle of the night or early morning the past few days, so I looked at the event logs in my Motorola MB7621 to see what was happening. Below is the most recent set of logs. Any idea what's going on? The system uptime is 43 days. I've also added the Downstream Bonded Channels table below.

Fri Nov 10 01:25:40 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:44 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:44 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:46 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:47 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:50 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:50 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:52 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:53 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:56 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:57 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:59 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:25:59 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:26:01 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:26:02 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:26:07 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:26:07 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:15 2023 Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:25 2023 Critical (3) SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:27 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:28 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:31 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:32 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:34 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:35 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:37 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:38 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:41 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:42 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:44 2023 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.0;CM-VER=3.0;
Fri Nov 10 01:27:52 2023 Notice (6) Honoring MDD; IP provisioning mode = IPv6
Mon Nov 20 09:57:21 2023 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=REDACTED;CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.0;

1 Locked QAM256 28 579.0 3.7 40.6 14243 14806
2 Locked QAM256 21 537.0 4.1 42.9 14874 13589
3 Locked QAM256 22 543.0 4.1 37.9 25517 21724
4 Locked QAM256 23 549.0 4.0 43.9 19132 33513
5 Locked QAM256 24 555.0 4.0 44.4 12604 4765
6 Locked QAM256 25 561.0 3.8 43.7 15800 20076
7 Locked QAM256 26 567.0 3.7 42.8 18126 30374
8 Locked QAM256 27 573.0 3.6 41.9 16791 12895
9 Locked QAM256 29 585.0 3.8 39.5 13083 13547
10 Locked QAM256 30 591.0 3.7 38.2 13493 12079
11 Locked QAM256 31 597.0 3.6 37.3 14885 5981
12 Locked QAM256 32 603.0 3.6 38.9 12176 3844
13 Locked QAM256 33 609.0 3.8 40.2 11631 3773
14 Locked QAM256 34 615.0 3.9 41.8 11200 3531
15 Locked QAM256 35 621.0 3.9 42.6 11071 3464
16 Locked QAM256 36 627.0 4.0 43.4 10773 3457
17 Locked QAM256 37 633.0 3.9 45.2 11033 3814
18 Locked QAM256 38 639.0 3.9 45.6 10783 3665
19 Locked QAM256 39 645.0 4.2 45.2 10723 3623
20 Locked QAM256 40 651.0 4.1 45.8 10521 3382
21 Locked QAM256 41 657.0 4.4 45.4 10391 2996
22 Locked QAM256 42 663.0 4.2 44.7 10631 2977
23 Locked QAM256 43 669.0 4.2 45.6 9837 2790
24 Locked QAM256 44 675.0 4.3 46.0 96182 103286
Total             405500 327951
   Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked ATDMA 1 5120 16.4 39.0
2 Locked ATDMA 2 5120 22.8 39.0
3 Locked ATDMA 3 5120 29.2 38.7
4 Locked ATDMA 4 5120 35.6 39.0
5 Not Locked Unknown 0 0 0 0.0
6 Not Locked Unknown 0 0 0 0.0
7 Not Locked Unknown 0 0 0 0.0
8 Not Locked Unknown 0 0 0 0.0

Question

 • 

Updated 

2 years ago

 • Edited

102

2

0

EG

Expert

 • 

111.5K Messages

2 years ago

@user_5w7r31 

Please post the *Upstream Power Level* numbers as well.

2

0

user_5w7r31

2 Messages

@EG​ Added! Let me know if other info would be helpful as well.

2 years ago

0

XfinityEva

Official Employee

 • 

1.8K Messages

@EG  Thank you for assisting @user_5w7r31 and providing that information about the levels. 

 

@user_5w7r31 Please send us a direct message with your full name and service address to get started. We can circle back here once we have more information and/or resolution. 

 

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2 years ago

EG

Expert

 • 

111.5K Messages

2 years ago

Okay, so the signal status values at that snapshot in time were OK but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) /  an upstream channel / return path impairment somewhere.

There are other signal stat values 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 (The Digital Care Team) who are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and those upstream receive signal stats.


You should get a reply here in your topic. Good luck !

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