Identifying and resolving network problems

Detecting network problems

You can detect network problems by going to the NetCache appliance console and using the ping command. The ping command verifies whether the NetCache appliance can communicate with other hosts on the network and whether other hosts can communicate with the NetCache appliance.

How to troubleshoot network problems

If you expect that the NetCache appliance should be able to connect with a host but ping does not respond with a message indicating that the host is alive, complete the following steps to troubleshoot the problem.

Step	Action
1	Check that the network cable is tightly connected to the proper interface connector.
2	Use the `ifconfig -a` command at the console to verify that the IP address and netmask are set correctly, and the up and running flags are displayed.
3	Use the `arp -a` command at the console to confirm that the NetCache appliance has the correct IP-to-Ethernet address map for the host you are trying to reach.
4	Use the `netstat -i` command at the console to check for excessive errors on the interfaces. If you see excessive input errors (ierrs) or output errors (oerrs), check the network connections on both ends of the connection. Bad transceivers or network hubs can sometimes introduce errors into the network. Collisions reported by the `netstat` command are a concern only if the NetCache appliance detects a substantial percentage of collisions, as compared to the total packet throughput. The goal is to keep collisions below 5 percent, but a network can operate properly (but slowly) with collision rates as high as 30 percent.
5	Run the `netstat -r` command to examine the routing tables.
6	Run the `route -s` command to find out the status of the default router.
7	Run the `ifstat -a` command to display statistics for all of the network interfaces on this NetCache appliance, including the virtual host and the loopback address.
8	Run the `traceroute` command to display the route that packets take to a network host.

Note
An improperly set up network router can also cause network problems. If a router is not working correctly or is not configured with the NetCache appliance's IP address, clients or hosts on the other side of the router cannot access the NetCache appliance through that router.

Contact technical support about other network problems

If you encounter other network problems, contact Network Appliance Technical Support for help, as described in Section G, Contacting Network Appliance Technical Support.