3. Troubleshooting Functional Failures in Operation543.6.2 IP Addresses Cannot Be Assigned Using DHCP Function(1) DHCP/BOOTP relay communication failureThere are three possible causes for DHCP/BOOTP relay communication failures:1. Configuration relating to DHCP/BOOTP relay has changed2. Network configuration has changed3. DHCP/BOOTP server failuresFor 2 above, check for the differences in the network configuration provided before and after the change. Check for anydifference disabling communication.Assuming that client settings (network card setting, cable connection, etc.) have been verified, this section describes theprocedure for locating the faulty part and cause in the cases described such as "IP addresses are not assigned from theDHCP/BOOTP server as a result of changing the configuration." and "Although the configuration and networkconfiguration are correct, IP addresses are not assigned and IP communication is disabled" as in above No. 1 and 3.To locate the faulty part and cause, follow the flow below.Figure 3-8: Troubleshooting on DHCP/BOOTP RelayVerify if there is a failure occurrence using the show logging command or the show ipinterface command.No failureexists.< IP addresses cannot be assigned to clients.>A failure exists.Identify the extent of failure using theping command.See the manuals "Message LogReference" and "3.6.1 Communication IsDisabled or Is Disconnected" and performthe actions described in [Action]associated with each log message.Communication betweenthe neighboring host androuter is disabled.Communication betweenremote host and router isdisabled.Verify the status of addressresolution using the show ip arpcommand.SolvedUnresolvedVerify the route information usingthe show ip route command.No routeinformationexists.The routeinformationexists.The next-hopaddress is invalid.Verify the IP network of remotesystem. Otherwise, go to"3.4 Network InterfaceCommunication Failure."Analyze the failure on eachrouting protocol.(RIP, BGP, etc.)Verify the settinginformation of filter andQoS.Verify the settinginformation of DHCP andBOOTP.
