Troubleshooting guide

3. Troubleshooting Functional Failures During Operation
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Switch is not possible, do the following:
1. Make sure the customer's terminal has the ping functionality.
2. Use the ping functionality to check whether communication between the customer's
terminal and the remote device is possible.
3. If communication with the remote device cannot be verified by using the ping
functionality, use the
ping operation command to check communication with each of
the devices up to the remote device, beginning with the device closest to the
customer's terminal.
4. If you are able to determine the range for the failure by using the ping functionality
and pinpoint the Switch that is likely to have the failure, log in to the Switch and
investigate the cause of the failure based on the failure analysis flowchart.
(5) Checking the ARP resolution information with a neighboring device
If the execution result of the ping operation command indicates that communication with a
neighboring device is impossible, the address might not have been resolved by ARP. To
check the status of address resolution between the Switch and the neighboring device, do
the following:
1. Log in to the Switch.
2. Use the
show ip arp operation command to check the status of address resolution
(whether ARP entry information exists) between the Switch and the neighboring
device.
3. If the address with the neighboring device has been resolved (ARP entry information
exists), see
(6) Checking the unicast routing information.
4. If the address has not been resolved (no ARP entry information exists), check
whether the IP network settings between the neighboring device and the Switch are
identical.
(6) Checking the unicast routing information
You need to check the route information obtained by the Switch if (a) communication is still
disabled after address resolution with the neighboring device is completed, (b)
communication is disabled on the route to the remote device during IPv4 unicast
communication, or (c) the route to the remote device has a problem. To carry out the check,
do the following:
1. Log in to the Switch.
2. Execute the
show ip route operation command to check the route information
obtained by the Switch.
3. If the route information obtained by the Switch contains route information about the
interface that caused the communication failure, the interface might have a problem
with the functionality shown below. That functionality must be checked.
 Filter functionality
See
(7) Checking the filtering and QoS configuration information.
(7) Checking the filtering and QoS configuration information
Certain packets might have been discarded by filtering or packets might have been
discarded by the shaper of QoS control.
Make sure that the setting conditions for filtering and QoS control in the configuration are
correct, and that the shaper is used appropriately in the system configuration. For details
about the procedure, see
3.13.1 Checking the filtering and QoS control configuration
information.