Indicates the status of the interface.
FR_STATUS_START is the state during rebooting or initial
start of circuit
FR_STATUS_RUNNING is the sate after the circuit is up (either LMI
successful or there is no DLCMI and the system just comes up).
FR_STATUS_FAULT is a transient state indicating that errors have
caused the circuit to be disabled until DLCMI recovery.
FR_STATUS_RECOVERED indicates that an the system has been in the
FR_STATUS_FAULT mode before, but has since recovered.