Fiber Optic Port Verification
As a troubleshooting aid, the fiber optic ports can be verified by placing a physical loopback optical line on the ports and verify the LED behavior as shown:
The ACT LED will arbitrarily be configured to either the A or B fiber line. The RAI LED is RED/GREEN indicating that there is something wrong at the far end of the fiber line (in this case, the remote unit is missing). The ALARM LED is RED because the T1 port is not connected. The STAT LED is RED when there is no fiber link but turns GREEN when the fiber link is valid.
NOTE
The T1 ports are all sending AIS. However, with the fiber looped, it is because of the LOS on the T1 port. Without the fiber looped, it is because of the LOS of the fiber port.
WARNING
An optical loopback will also loop back the Ethernet port. If the network cannot tolerate this, remove the Ethernet port connection before connecting the fiber loopback.
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