3. Troubleshooting Functional Failures in Operation58communication to the other party cannot be verified with the ping command, use ping to check communicationtoward clients starting from the system closest to this system. For an example of issuing ping and how to interpretthe result, see the manual "Configuration Settings."3. If the server and the client are directly connected, check the HUB and cable connections.4. Depending on the extent of failure detected by the ping command, that is the neighboring system or remote system,proceed to the next step in the failure analysis flow.(d) Checking route informationCheck the route information acquired by this system if communication is not possible even when the address resolutionwith the neighboring system is achieved, or if communication is disabled in the midway to the other party, or if theroute to the other party is abnormal. Use the following procedure:1. Log in to the system.2. Execute the show ip route command to check the route information acquired by this system.(e) Checking filtering/QoS setting informationOnly certain packets may have been discarded by filtering, or packets may have been discarded through bandwidthmonitoring, discarding control, or shaper of the QoS control.Check to see if the conditions of filtering and QoS control in the configuration have been set up correctly and ifbandwidth monitoring, discarding control, or shaper has been set up appropriately for system operation in systemconfiguration, on this system and on the relay equipment located between the client and server. For the procedure, see"3.23.1 Checking Filtering/QoS Setting Information ."(f) Checking layer 2 networkIf no setting error or failure is found in steps (a) to (e), the layer 2 network may have problem. Check the layer 2network, referring to "3.5 Layer 2 Network Communication Failure"3.6.3 DynamicDNS Cooperation in DHCP Function Is Disabled(1) DHCP server communication troubleFollowing are three possible causes for DHCP server communication failures.1. Configuration error2. Network configuration has changed3. DHCP server failureFirst, check 1 above. This section describes configurations that are easily misconfigured. For 2 above, check for thedifferences in the network configuration provided before and after the change. Check for any difference disablingcommunication. If the DNS server/DHCP server settings (network card setting, cable connection, etc.) have beenconfirmed to be normal, and if the configuration and network configuration are correct but IP communications areunavailable because IP addresses cannot be assigned to clients, as described in 3 above, see "(b)Checking timeinformation" through "(f)Checking filtering/QoS setting information" for details.To locate the failed part and cause, follow the flow below.
