3Com 9100 User Manual page 151

Using the Command-Line Interface 151
attempt to log in and the maximum number of Telnet sessions are being
used, you should receive an error message indicating so.
Traps are not received by the SNMP Network Manager:
Check that the SNMP Network Manager's IP address and community
string are correctly configured, and that the IP address of the Trap
Receiver is configured properly on the system.
The SNMP Network Manager or Telnet workstation can no longer
access the device:
Check that Telnet access or SNMP access is enabled.
Check that the port through which you are trying to access the device has
not been disabled. If it is enabled, check the connections and network
cabling at the port.
Check that the port through which you are trying to access the device is
in a correctly configured VLAN.
Try accessing the device through a different port. If you can now access
the device, a problem with the original port is indicated. Re-examine the
connections and cabling.
A network problem may be preventing you accessing the device over the
network. Try accessing the device through the console port.
Check that the community strings configured for the device and the
Network Manager are the same.
Check that SNMP access was not disabled for the system.
Permanent entries remain in the FDB:
If you have made a permanent entry in the FDB (which requires you to
specify the VLAN to which it belongs and then delete the VLAN), the FDB
entry will remain. Though causing no harm, you must manually delete the
entry from the FDB if you want to remove it.