Operation
3-6 3160-A2-GB21-80
March 1999

Table 3-1. System LEDs

Name Color Meaning
OK Green Indicates the current operational state of the DSU/CSU.
ON:
The DSU/CSU is operational and has power.
OFF:
The DSU/CSU is performing a power-up self-test or a
system failure has occurred.
BLINKING:
A software download is in progress.
FAST BLINK:
The carrier-mounted DSU/CSU is currently
selected by the SDCP.
FAIL Yellow Indicates a system failure or a self-test.
ON:
A device error/fault is detected or a reset has just
occurred.
OFF:
No system failures are detected.
BLINKING
: A self-test is in progress.
TEST Yellow A system test is in progress.
ON:
A loopback or pattern test has been initiated either
locally, by the network, or externally.
OFF:
No tests are active.

Table 3-2. Network Interface LEDs (1 of 2)

Name Color Meaning
SIG Green Monitors the signal being received from the network.
ON:
A recoverable signal is being received from the
network.
OFF:
The signal cannot be recovered from the network (a
Loss of Signal condition exists).
OOF Yellow Monitors Out Of Frame (OOF) conditions on the received
network signal.
ON
: At least one OOF was detected on the signal during the
sampling period.
OFF:
No OOFs were detected on the signal during the
sampling period.