724-746-5500 | blackbox.com
Page 29
Chapter 7: Troubleshooting
7. Troubleshooting
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 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 100 Mbps, 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 Gigabit Managed PoE+ Switches 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 Gigabit Managed PoE+ Switch 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 and mis-wired 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 5 cable tester for every 100Base-TX and 1000BASE-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, make sure that your network topology contains no data path loops.
• Check the port configuration. A port on your Gigabit Managed PoE+ Switch may not be operating as you expect because it
has been put into a “ blocking” state by Spanning Tree, GVRP (automatic VLANs), or LACP (automatic trunking). (Note that the
normal operation of the Spanning Tree, GVRP, and LACP features may put the port in a blocking state.) Or, the port just may
have been configured as disabled through software.
Table 7-1. Troubleshooting Chart.
Symptom Action
POWER LED is Off • Check connections between the switch, the power cord and the wall outlet.
• Contact Black Box Technical Support at 724-746-5500 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 types 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.
To Next Page
Loading...
