Verilink C100 (880-502893-001) Product Manual - Manual (Page 88)

Performance Monitoring with the Console Port
8-12 Verilink C100 and C150 T1/FT1 CSU/DSU 6/15/99
Chan TX and RX LEDs
The two asterisks next to TX and RX represent LEDS which reflect the
status of transmit and receive data on the Channel Interface. These
indicators are on when data spacing and off when data is marking.
Chan CD LED
The asterisks next to CD represents the status of the Carrier (RLSD)
control signal being sent to Synchronous Channel. When On, Carrier is
high and when off, Carrier is low.