3. Troubleshooting Functional Failures in Operation713.9 IPv6 Network Communication Failure3.9.1 Communication Is Disabled or Is DisconnectedThere are three possible causes that result in communication failure on the IPv6 network using this system.1. Configuration on IPv6 communication has changed2. Network configuration has changed3. Network component failuresFor 1 and 2 above, check for the differences in the configuration and network configuration provided before and afterthe change. Check for any difference disabling communication.This section describes procedure to identify the failed part and to isolate the problem, mainly for the cases of "IPv6communication is disabled although the configuration and network configuration are correct." and "IPv6communication had been normally running but it is disabled now." as described in 3 above.To locate the faulty part and cause, follow the flow below.Figure 3-13: Failure Analysis Procedure When IPv6 Communication DisabledVerify if there is an occurrence of line failure using the showlogging command.No physical failuremessage exists.A physical failuremessage exists.Check the Up/Down status of the interfaceusing the show ipv6 interface command.see the manual "Message Log Reference"andperform the action described in [Action]associated with each log message.Identify the extent of failure using theping ipv6 command.Go to "3.4 Network InterfaceCommunication Failure."Communication between theneighboring host and routeris disabled.Communication between theremote host and router isdisabled.Unicast communicationSolvedUnresolveThe routeinformationexists.Verify the status ofaddress resolutionusing the show ipv6neighbors command.Verify the routeinformation using theshow ipv6 routecommand.Verify RA addressdistribution.Distributed NotdistributedNo route information exists or thenext hop address is invalid.Verify the IP network ofremote system. Otherwise, goto "3.4 Network InterfaceCommunication Failure."Analyze the failure on eachrouting protocol. (RIPng,BGP4+, etc.)Verify the filtersettings.Verify the RAsettings.
