Configuring Port-Mirroring Instances on M120 Routers
You can associate only one port-mirroring instance with a specific FEB on an M120 router.
To associate a port-mirroring instance with a FEB, include the port-mirror-instance port-mirroring-instance-name statement at the [edit chassis feb slot-number] hierarchy level:
The properties of the port-mirroring instance associated with the FEB override any global port-mirroring properties (configured by including the port-mirroring statement at the [edit forwarding-options] hierarchy level.)
In a FEB redundancy group, you must associate a port-mirroring instance only with the primary FEB. During failover or switchover, the port-mirroring instance is automatically associated with the backup FEB that fails over or switches over as the primary FEB.
For information about configuring FPC-to-FEB connectivity on an M120 router, see Enabling FPC to FEB Connectivity on M120 Routers.