3Com 3C13636 Configuration Manual page 262

3Com Router 3000 Ethernet Family
Configuration Guide
operating mode is incorrect, i.e. one party of the connection is working in full duplex
mode while the other party in half duplex mode, fault will occur. That is, when the
network traffic increases, the party operating in half duplex mode shows frequent
network collisions. For example, if Hub is connected, all the other devices in the whole
network segment will have serious network collisions. The party operating in full duplex
mode will receive a large amount of error messages, accompanied with serious
message losses at both parties. In this case, use display interface ethernet command
to view the error ratio of transmitting and receiving messages on the Ethernet interface.
Usually, the collision can be observed through the state LEDs of the Ethernet interface.
Step 4: Check that flow-control mode of Ethernet interface is correct.
By default, negotiation flow-control is adopted in Ethernet interface. If forced
flow-control mode is used at the peer end, the interface might not be able to go up. In
this case, please keep the flow-control mode the same at both ends. Restart the
interface using the shutdown and undo shutdown commands.
Contact our technical support engineers if you still cannot locate the problem by using
the above methods.
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Chapter 2 LAN Interface Configuration