Transition Networks
SM24T6DPA Web User Guide
33664 Rev. B
Page
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Troubleshooting
Most problems are caused by the following situations. Check for these items first when
starting your troubleshooting.
Basic Troubleshooting Tips
Connecting to devices that have 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 SM24T6DPA behaves 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 SM24T6DPA 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 the switch may not be operating as you expect because it has been put into a
“ blocking” state by Spann
ing 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.
