Troubleshooting tips

These troubleshooting tips enable you to solve basic TCP/IP problems.

You can find out how to check logs and verify that your interfaces and other network components are active.

If you are experiencing problems related to TCP/IP, you should check for error messages in the QTCP message queue located in library QUSRSYS. Many errors relating to TCP/IP functions get logged in this message queue. To display the QTCP messages, enter DSPMSG QUSRSYS/QTCP on the command line.

Server table
You can use this server table as a reference to find out how servers, server jobs, job descriptions, and subsystems are mapped to one another.
Checking jobs, job logs, and message logs
You can view jobs, job logs, and messages to identify problems and make adjustments to solve them.
Checking for active filter rules
Your network communications might be failing because IP packet filters are stopping your incoming or outgoing data. You can find out if filter rules are limiting your communication.
Verifying system startup considerations for networking
You need to start subsystems, TCP/IP, interfaces, and servers in the correct order and know how to locate problems associated with startup.
Varying on lines, controllers, and devices
Your line descriptions, network server descriptions, and network interface descriptions should be configured to vary on when you start TCP/IP interfaces. The configuration allows these objects to start as part of starting TCP/IP interfaces. You vary on these objects by specifying these objects not to be online at IPL time.
Verifying the logical partition configuration
You might need to verify that the logical partition (LPAR) configuration is correct.
Troubleshooting IPv6–related problems
If you are using IPv6 for network connectivity, you can use several of the same troubleshooting tools as you do for IPv4. For instance, you can use trace route and Ping to test connections and routes for both types of networks. In addition, you can use the Netstat and communications trace functions for IPv6.

Parent topic: Troubleshooting tools and techniques