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3. Troubleshooting Functional Failures in Operation
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Figure 3-7: Failure Analysis Procedure When IPv4 Communication Disabled
(1) Checking log
Communication may be interrupted by a line failure (or damage). The following procedure displays hardware error
messages among this system's log messages.
For details about the log, see the manual "Message Log Reference."
1. Log in to the system.
2. Display the log using the show logging command.
3. The date and time when an error occurred are displayed in the log. Check to see if a log was displayed at the date/
time when communication was disabled.
4. For detailed information about the failure in the log displayed at the time and date of the communication interruption
and the actions for failures, see the manual "Message Log Reference." Follow the instruction.
5. If there is no log recorded at the time and date when communication was disabled, go to "(2)Checking interface
status."
Verify if there is a line failure log message.
A line failure log message exists.
No line failure log message exists.
Check the Up/Down status of the interface.
See the manual"Message Log Reference"and
perform the action described in [Action]
associated with each log message.
Identify the extent of the failure using the ping
command.
Go to "3.4 Network Interface Communication
Failure."
Communication between the neighboring host and router is disabled.
Communication
between remote
host and router is
disabled.
Verify the status of address resolution using the show ip arp command.
Solved
Verify the route information using the
show ip route command.
Unresolved
No route information
exists or the next hop
address is invalid.
Go to "3.7 IPv4 Unicast Routing Communication
Failure"
The route
information exists.
Verify the IP network of remote system.
Otherwise, go to "3.4 Network Interface
Communication Failure."
<IPv4 communication is disabled.>
Confirm Option License OP-NPAR.
VRF interface is not displayed
down
up
Go to "3.6.2 IP Addresses Cannot Be Assigned
Using DHCP Function" and "3.23.1 Checking
Filtering/QoS Setting Information."