E1 Port Verification
By placing a physical loopback connection on the E1 port, a valid signal can be detected by each individual E1 port to verify its operation. Without the fiber looped, the ALARM LED for the looped E1 port will show RED/GREEN indicating there is a problem at the far end of the fiber transport (In this case the far end unit is missing) and the STAT LED is RED because the fiber is in LOS. With the fiber looped, the E1 port will only show a normal GREEN STAT LED.
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