Loop detection protocols like EAPS (Extreme Automatic Protection Switching)/ERPS (Ethernet Ring Protection Switching) want to depend upon CFM to detect link status for faster failover recovery.
They register with LMEP and RMEP objects created by CFM in order to receive the link status event notifications to take the necessary action.
Currently LMEP is identified with domain, association, port, MEPId quadruples. And RMEP is identified with domain, association, LMEP, RMEPId quadruples. Each LMEP can be tied up to multiple RMEPs. So applications need to configure domain, association, LMEP and RMEPs through a client/server interface.
To simplify this, CFM provides a simple API to client applications to register/deregister CFM with a specified string name. The string name can be identified as a CFM group that binds an LMEP to multiple RMEPs. The group name is unique across the switch. Each application can create its own group for a required LMEP/RMEP combination.
You can associate a group to each LMEP created on a port. There exists a one-to-one relationship between LMEP-port-group. Whenever CFM stops receiving CCMs on this port, it informs a group DOWN event to registered clients like ERPS/EAPS. Whenever CFM starts receiving the CCMs again on this port, a group UP event is sent to registered clients.
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