Filter
Top Products
3. Troubleshooting Functional Failures in Operation
60
(d) Identifying the extent of the failure (performed from this system)
If no failure is found on this system, a failure may exist somewhere in the route between this system and the remote
system. The procedure to locate the failure in the route to the remote system and identify the failure range is as follows:
1. Log in to the system.
2. If a router is provided between the DNS server and DHCP server, use the ping command to verify communication
of the system (router) between the DHCP server and the other system (DNS server) to which communication is
disabled. If communication to the other party cannot be verified with the ping command, use ping to check
communication toward clients starting from the system closest to this system. For an example of issuing ping and
how to interpret the result, see the manual "Configuration Settings."
3. If the DNS server and DHCP server 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.
(e) Checking route information
Check the route information acquired by this system if communication is not possible even when the address resolution
with the neighboring system is achieved, or if communication is disabled in the midway to the other party, or if the
route 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.
(f) Checking filtering/QoS setting information
Only certain packets may have been discarded by filtering, or packets may have been discarded through bandwidth
monitoring, 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 if
bandwidth monitoring, discarding control, or shaper has been set up appropriately for system operation in system
configuration, on this system and on the relay equipment located between the DNS server and DHCP server. For the
procedure, see "3.23.1 Checking Filtering/QoS Setting Information."
(g) Checking layer 2 network
If no setting error or failure is found in steps (a) to (f), the layer 2 network may have problem. Check the layer 2
network, referring to "3.5 Layer 2 Network Communication Failure."