Troubleshooting guide

3. Troubleshooting Functional Failures During Operation

Figure 3-14: Failure analysis procedure on IPv6 DHCP relays

(1) Checking the log and interface

One probable cause of disabled assignment of prefixes or addresses to clients is that

communication between the client and the server has been disabled. Check the log displayed by

the Switch or use the

show ipv6 interface command to check whether the interface status is Up

Down. For details about the procedure, see 3.10.1 Communication is not possible or is

disconnected.

(2) Identifying the range for a failure

If a failure has not occurred on the Switch, a failure might have occurred somewhere on the route

between the Switch and the remote devices. To identify the range for a failure in order to determine

the fault location on the route, do the following:

1. Log in to the Switch.

2. Use the

ping ipv6 command to check the communication with the two remote devices that

are unable to communicate. For details about examples of using the

ping ipv6 command and

how to interpret the execution result, see the Configuration Guide.

3. If communication with the remote devices cannot be verified by the

ping ipv6 command,

execute the command again to check communication with each of the devices up to the remote

device, beginning with the device closest to the Switch.

4. If the execution result of the

ping ipv6 command indicates that the failure occurred on the

neighboring device, see (3) Checking the NDP resolution information with a neighboring

device. If the execution result indicates a failure on the remote device, see (4) Checking the

unicast routing information.

(3) Checking the NDP resolution information with a neighboring device

If the result of the

ping ipv6 command indicates that communication with a neighboring device is

disabled, the address might not have been resolved by NDP. To check the status of address

resolution between the Switch and the neighboring device, do the following: