2–22
DECbridge 500/600 Problem Solving
2.4.6.4
Running the Loopback Test and Observing the Results
1. Reconnect the power cord to the ac outlet.
2. Observe the state of the LED indicators on the FI module after the self-test
diagnostic is complete.
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If the FI port fault disappears (that is, if the FI_BAD indicator turns off,
measure the transmit power and receive power at the bridge using the
SDU power meter (Section 2.4.7). If the power levels are within specifi-
cation, reconnect the interface cables and rerun the bridge self-test.
–
If the FI port fault indication persists, the problem is in the bridge. Make
sure the FI module is fully seated. Replace it if necessary.
3. Observe the state of the NI_BAD indicator on the NI module.
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If the NI_BAD indicator turns off, the problem is external to the bridge.
Check the interface cable and the device connected to the other end of the
cable. The LED on the loopback connector should be on.
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If the NI_BAD indicator remains on, the problem is in the bridge. Make
sure the NI module is fully seated. Replace it if necessary.
2.4.6.5
Returning to Normal Operation
When you have completed loopback testing of the ports, follow these steps to return
the bridge to normal operation:
1. Disconnect the power cord from the ac outlet.
2. Set the Enable External Loopback switch (switch 7) to the OFF (up) position.
3. Remove the FI loopback connector and reconnect the FI interface cable(s).
4. Remove the NI loopback connector from the NI interface selected by the
AUI/ThinWire switch, and reconnect the NI interface cable to that port.
5. Reconnect the power cord to the ac outlet.
