CFM Alarms

If CFM detects a fault in an end-to-end link, it triggers an alarm. The alarm is sent to the network management system (NMS) so that a network administrator can take appropriate measures to rectify the fault.

Alarm Anti-jitter

On an unstable network enabled with CC, multiple alarms and clear alarms may be generated. These alarms consume system resources and deteriorate system performance. RMEP activation time can be set to prevent false alarms. Alarm anti-jitter time can be set to limit the number of alarms generated.

**Table 1** Alarm anti-jitter
Function	Description
RMEP activation time	The RMEP activation time helps prevent false alarms. It is actually the time reserved for users to configure RMEPs. A local MEP with the ability to receive CCMs can accept CCMs only after the RMEP activation time elapses. If the local MEP does not receive CCMs in three consecutive intervals for sending CCMs, the local device considers that a connectivity fault has occurred between the local MEP and the RMEP. The local device then generates an RMEP connectivity fault alarm.
Alarm anti-jitter time	If a MEP detects a connectivity fault: After the anti-jitter time elapses, it sends an alarm to the NMS. If the fault is rectified before the anti-jitter time elapses, it does not send an alarm.
Clear alarm anti-jitter time	If a MEP detects a connectivity fault and sends an alarm: If the fault is rectified within the clear alarm anti-jitter time, it sends a clear alarm. If the fault is not rectified within the clear alarm anti-jitter time, it does not send a clear alarm.

Alarm Suppression

If different types of faults trigger multiple alarms, CFM alarm suppression allows only the alarm with the highest level to be sent to the NMS. If other alarms remain after the highest-level alarm is cleared, the alarm with the second highest level is sent to the NMS. This process repeats until all alarms are cleared.

The rationale behind CFM alarm suppression is as follows:

High-level alarms require immediate troubleshooting.
A single fault may trigger alarms of different levels. After the highest-level alarm is cleared, these lower-level alarms may be cleared without further input required.