Troubleshooting guide

3. Troubleshooting Functional Failures During Operation
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(c) Identifying the range for a failure (from the Switch)
If a failure has not occurred on the Switch, a failure might have occurred somewhere on the
route between the Switch and the remote device. To identify the range for a failure in order
to determine the fault location on the route, do the following:
 Log in to the Switch.
 If there are devices such as an L3 switch between the client and the server, use the
ping operation command to check the communication between the L3 switch and
the remote device (DHCP client). If the communication with the remote device
cannot be verified by using the
ping operation command, execute the ping
operation command again to check communication with each of the devices up to
the client, beginning with the device closest to the Switch. For details about
examples of using the
ping operation command and how to interpret the execution
result, see the Configuration Guides.
 If the server and the client are directly connected, check the hub and cable
connections.
(d) Checking the filtering and QoS configuration information
If communication is not possible even when there is no physical failure on the Switch,
certain packets might have been discarded by the filtering functionality or packets might
have been discarded by the shaper of the QoS functionality. Therefore, on the Switch and
relay device between the client and server, check in the system configuration whether the
setting conditions for the filtering functionality and QoS control in the configuration are
correct and whether the shaper is used appropriately. For details about the procedure,
see
3.13.1 Checking the filtering and QoS control configuration information.
(e) Checking the Layer 2 network
If you do not find any incorrect settings or a failure in the steps (a) to (e), there might be a
problem with the Layer 2 network. Check the Layer 2 network according to
3.5 Layer 2
network communication failures.
3.7.3 Communication failures occurring when MAC-based authentication is
used
If communication is not possible when IMAC-based authentication is used, isolate the
cause of the problem according to the failure analysis method described in the following
table.
Table 3-29 Failure analysis method when MAC-based authentication is used
No. Items to check and commands Action
1 Check whether communication with
the terminal is possible.
 If authentication in local authentication mode is not possible,
go to No. 2.
 If authentication in RADIUS authentication mode is not
possible, go to No. 3.
 For other cases, go to No. 6.
2 Use the show
mac-authentication
mac-address operation command
to make sure the MAC address and
VLAN ID are registered.
 If the MAC address is not registered, use the set
mac-authentication mac-address operation
command to register the MAC address and VLAN ID. After
registration, use the commit mac-authentication
operation command to check the information for the
operation.