Cisco 7000 Series Hardware Installation And Maintenance Manual page 267

LED DTE Signal
Conn Connected
The labels on each LED indicate the signal state when the FSIP port is in DTE mode. However, the
direction of the signals is reversed when the FSIP port is in DCE mode. For example, a DCE device
usually generates a clock signal, which it sends to the DTE device.
Therefore, when the Receive Clock (RxC) LED goes on, on a DTE interface, it indicates that the
DTE is receiving the clock signal from the DCE device. However, when the RxC LED goes on, on
a DCE interface, it indicates that the DCE is sending a clock signal (RxC) to the DTE device.
Because of limited space on the FSIP faceplate, only DTE mode states are labeled on each port.
Figure B-11 shows the signal flow between a DTE and DCE device and the LEDs that correspond
to signals for each mode. The following LED state descriptions include the meanings for both DTE
and DCE interfaces.
•
RxC— On DTE interfaces, this LED is on when the port is receiving a transmit clock signal
(TxC) from the remote DCE device, which is usually a DSU or modem.
On DCE interfaces, this LED indicates TxC (Transmit Clock). This LED is on when the DCE
port is sending a transmit clock (TxC) signal to the remote DTE device.
•
RxD (Receive Data)—On DTE interfaces, this LED is on when the port is receiving data signals
(packets) from the network through the remote DCE device. This LED is also on when it detects
an idle pattern that is commonly sent across the network during idle time.
On DCE interfaces, this LED indicates TxD (transmit data). During normal DCE operation, this
LED is on when the DCE port is receiving data packets from the network through the remote
DTE device.
•
TxC (Transmit Clock)—On DTE interfaces, this LED is on when the port is receiving the
transmit clock signal from the remote DCE.
On DCE interfaces, this LED indicates receive clock (RxC). During normal DCE operation, this
LED is on when the DCE port is sending the internal clock signal (which the FSIP generates) to
the remote DTE device, which is usually a host, PC, or another router.
•
Conn (connected or loopback)—On both DTE and DCE interfaces, this LED is on to indicate
normal operation: the FSIP is properly connected to the external device, and TA (DTE available)
and CA (DCE available) are active. When this LED is off, the FSIP is in loopback mode or is not
connected to the network or external device. (See Table B-2.)
Figure B-11 DTE to DCE Signals
DCE Signal
Connected
Interface Processor LEDs
Reading LED Indicators B-9