received - on for a space and off for a mark.
DSU Data Service Unit (DSU) LED lights when the unit is in the
NS The No Signal (NS) LED lights when no signal is received from the network or when the signal is too weak for normal operation.
OOS The Out Of Service (OOS) LED lights when an outage condition occurs. This happens when there is a failure in the digital service that is detected by the network and the telco sends a repetitive OOS sequence.
CD The Carrier Detect (CD) LED lights when a carrier signal is received from the network.
Trunk
CN Congestion (CN) LED lights when congestion is detected on the trunk.
LK Link (LK) LED blinks slowly when there is no link management connection with the network. Blinks quickly when link management is established with the network. Remains solid ON when the network indicates the PVC is active.
CD Carrier Detect (CD) LED lights when a carrier signal is detected from the network.
TD Transmit Data (TD) LED blinks when data is being transmitted - on for a space and off for a mark.
RD Receive Data (RD) LED blinks when data is being received - on for a space and off for a mark.
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