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Cisco Network Modules Hardware Installation Guide
OL-2485-20
Chapter 13 Connecting HSSI Network Modules
HSSI Network Module LEDs
Table 13-1 HSSI Network Module LEDs
LED
Meaning
LB/C
(Loopback/Connect)
Green indicates normal operation. The module is connected to the external
DSU, and the signals TA (DTE available) and CA (DCE available) are active.
Yellow indicates that the module is in loopback mode.
If this LED is off, the port is neither connected to the DSU nor in loopback
mode.
RC (Receive Clock)
Module has detected a receive clock signal. During normal operation, this
signal is received from the external DSU. During loopback, it is generated
internally.
RD (Receive Data)
Module has detected a receive clock signal. During normal operation, this
signal is received from the external DSU. During loopback, it is generated
internally.
TC (Transmit Clock)
Module is transmitting a clock signal to the external DSU. During normal
operation, this signal is derived from the DSU’s RT signal. During loopback,
it is generated internally.
TD (Transmit Data)
Module has been detected by and can send packets to the external DSU.