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Chapter 8: Troubleshooting
8. Troubleshooting
8.1 Basic Troubleshooting Tips
Most problems are caused by the following situations. Check for these items first when starting your troubleshooting:
• Connecting to devices that have a fixed full-duplex configuration.
The RJ-45 ports are configured as “Auto”, that is, when connecting to the attached devices, the switch will operate in one of
two ways to determine the link speed and the communication mode (half-duplex or full-duplex):
- If the connected device is also configured to Auto, the switch will automatically negotiate both link speed and communication
mode.
- If the connected device has a fixed configuration, for example 10 Gbps, at half- or full-duplex, the switch will automatically
sense the link speed, but will default to a communication mode of half-duplex.
Because the LGB5510A switch devices behave in this way (in compliance with the IEEE 802.3 standard), if a device connected to
the switch has a fixed configuration at full duplex, the device will not connect correctly to the switch. The result will be high
error rates and very inefficient communications between the switch and the device.
Make sure all devices connected to the LGB5510A switch devices are configured to autonegotiate, or are configured to connect
at half-duplex (all hubs are configured this way, for example).
• Faulty or loose cables. Look for loose or obviously faulty connections. If they appear to be OK, make sure the connections are
snug. If that does not correct the problem, try a different cable.
• Non-standard cables. Non-standard cables may cause network collisions and other network problems, and can seriously impair
network performance. Use a new correctly-wired cable for pinouts and correct cable wiring. We recommend using a Category
6a cable tester for every 1000BASE-TX and 10GBASE-T network installation.
• Improper Network Topologies. Make sure you have a valid network topology. If you no longer experience the problems, the
new topology is probably at fault. In addition, you should make sure that your network topology contains no data path loops.
Table 8-1. Troubleshooting chart.
Symptom Action
System LED is Off • Check connections between the switch, the power cord, and the wall outlet.
• Contact Black Box Technical Support at 7234-746-5500 or info@blackbox.com.
Link LED is Off • Verify that the switch and attached device are powered on.
• Be sure the cable is plugged into the switch and corresponding device.
• If the switch is installed in a rack, check the connections to the punch-down block and patch panel.
• Verify that the proper cable type is used and its length does not exceed specified limits.
• Check the adapter on the attached device and cable connections for possible defects. Replace the
defective adapter or cable if necessary.
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