The properties of the port-mirroring instance associated
with an FPC override any global port-mirroring properties (configured
by including the port-mirroring statement at the [edit
forwarding-options] hierarchy level.)
Layer 2 VPLS port mirroring is supported only for Enhanced
III FPCs on M320 routers.
Ensure that the port-mirroring-instance-name specified at the [edit chassis fpc slot-number] hierarchy level matches the port-mirroring-instance-name configured at the [edit forwarding-options port-mirroring
instance port-mirroring-instance-name] hierarchy