Troubleshooting

Unusual Network Activity

QoS-Related Problems

Loss of communication when using VLAN-tagged traffic. If you cannot communicate with a device in a tagged VLAN environment, ensure that the device either supports VLAN tagged traffic or is connected to a VLAN port that is configured as Untagged.

Radius-Related ProblemsThe switch does not receive a response to RADIUS authentication

requests. In this case, the switch will attempt authentication using the secondary method configured for the type of access you are using (console, Telnet, or SSH).

There can be several reasons for not receiving a response to an authentication request. Do the following:

Use ping to ensure that the switch has access to the configured RADIUS server.

Verify that the switch is using the correct encryption key for the desig­ nated server.

Verify that the switch has the correct IP address for the RADIUS server.

Ensure that the radius-server timeout period is long enough for network conditions.

Verify that the switch is using the same UDP port number as the server.

RADIUS server fails to respond to a request for service, even though

the server’s IP address is correctly configured in the switch. Use show radius to verify that the encryption key the switch is using is correct for the server being contacted. If the switch has only a global key configured, then it either must match the server key or you must configure a server-specific key. If the switch already has a server-specific key assigned to the server’s IP address, then it overrides the global key and must match the server key.

C-18