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Avaya CM cmgSyncSignalFault

Jeremy Boilard

Problem Statement

Avaya Communication Manager (Core) reports a Major cmgSyncSignalFault alarm with alarm code ACT, indicating that the synchronization signal was lost for the provisioned clock-sync source on a media gateway or E1/T1 media module.

Impact

Loss of the configured external synchronization reference can cause the gateway or E1/T1 span to fall back to the internal clock source. If unresolved, this may contribute to timing slips or service quality issues on affected trunks. The gateway may still remain up while the sync alarm is active.

Alarm

cmgSyncSignalFault - Synchronization signal lost; Alarm Code: ACT; Severity: Major

Troubleshooting Steps

  1. Confirm the affected Avaya Communication Manager core and media gateway are reachable and that the gateway is up.
  2. Access the Media Gateway Processor (MGP) CLI for the affected gateway.
  3. Run `show sync timing` to verify the currently provisioned clock-sync source and whether the source has a good signal and is active.
  4. If the synchronization source is an E1/T1 media module such as MM710, confirm that the E1/T1 media module has been added properly on the server.
  5. If the E1/T1 media module has not been added, use the System Access Terminal (SAT) and run the appropriate `add DS1` command before attempting MGP CLI synchronization commands.
  6. From the MGP CLI, configure the primary and secondary clock sources for the E1/T1 span using the `set sync interface` command. The internal/local clock is built in and is not administrable from the CLI.
  7. Use the `set sync source` command to select the specific E1/T1 media module to be used as the active clock reference.
  8. Run `show sync timing` again to confirm that the intended synchronization source is provisioned and active.
  9. If local visual inspection is available, check the Yellow LED on the MM710 media module. Yellow LED on for approximately 2.7 seconds and off for 0.3 seconds indicates active mode using an external synchronization source. Yellow LED on for approximately 0.3 seconds and off for 2.7 seconds indicates active mode using the internal on-board clock, meaning the external sync timing was not successfully applied.
  10. If the external source does not show a good signal, investigate the upstream E1/T1 provider circuit, cabling, media module, and configured clock source before reapplying synchronization settings.

Resolution

Restore or correctly provision the external synchronization source, then verify with `show sync timing` that the desired clock reference is active. The cmgSyncSignalFault alarm should clear after the gateway detects a valid synchronization signal. If the source remains unavailable, keep the gateway on internal clock as a temporary state only and escalate to the circuit or Avaya support team for further investigation.