Troubleshooting VLAN Issues
The following are three steps in troubleshooting VLAN problems:
■ Check the physical connectivity—Make sure the cable, the network
adapter, and switch port are good. Check the port’s link LED.
■ Check the switch configuration—If you see FCS errors or late collisions,
suspect a duplex mismatch. Also check configured speed on
both ends of the link. Increasing collisions can mean an overloaded
link, such as with a broadcast storm.
■ Check the VLAN configuration—If two hosts cannot communicate,
make sure they are both in the same VLAN. If a host cannot connect to
a switch, make sure the host and the switch are in the same VLAN.