Lantronix
SM4T4DPA Install Guide
33867 Rev. A
Page
21
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29
Troubleshooting
Basic Troubleshooting Tips
Most problems are caused by the following situations. Check for these items first to start your troubleshooting:
Connecting to devices with a fixed full-duplex configuration
: The RJ-45 ports are configured as “Auto”. That is,
when connecting to 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 100Mbps, 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 SM4T4DPA behave in this way (in compliance with the IEEE802.3 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 SM4T4DPA Switch devices are configured to auto negotiate 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 miswired 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. A category 5 cable tester is a recommended tool for every 100Base-TX and 1000Base-T network
installation.
Improper Network Topologies
: It is important to 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.
Check the port configuration
: A port on your 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 via software.
Troubleshooting Chart
Symptom
Action
POWER LED is Off
◆
Check connections between the switch, the power cord and the wall outlet.
◆
Contact your dealer for assistance.
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