The microwave link Fast Fault Detection (FFD) capability allows a 7705 SAR-8 Shelf V2 or 7705 SAR-18 to directly detect MPR-e radio or microwave link faults using proprietary messaging. The following fault types are detected by FFD:
a radio signal failure
an MPR-e radio hardware failure
an incompatible MPR-e radio setting
a High Bit Error Rate (HBER) condition
a Remote Defect Indication (RDI) condition
FFD does not cause the SSU to disqualify the microwave link as a clock source if a fault condition is detected; SSM must be enabled in order to provide this function.
The microwave link hold time (hold-up time and hold-down time) must be configured in order to suppress link flapping. The hold-up and hold-down times delay advertising the transition of the microwave link status to the upper layer applications, including IP/MPLS and SSU. The hold-time range is between 0 and 900 s.
If microwave link faults are detected, an event is logged and the link is disabled. Some detected faults may be selectively suppressed using the suppress-faults command. When faults are suppressed, the event is still logged, but the microwave link is not disabled. Operators can suppress HBER faults, RSL threshold crossing faults, and/or RDI faults. By default, the system does not suppress faults for FFD.