Communications trace

You can use communications trace to determine whether your data is being transmitted correctly across the network.

Use the communications trace function to troubleshoot TCP/IP. Communications trace is a service function that allows the data that flows over a communications line, such as a local area network (LAN) or wide area network (WAN), to be captured for analysis. The communications trace traces only the packets received by or sent from i5/OS^®. It does not trace other packets flowing on the network. After the data has been traced, the raw data can be dumped into a stream file, or it can be formatted and placed in a spooled file to be displayed or printed.

If your system is multihomed, data might be sent on one interface and received on a different interface. In this situation, you should trace two communications lines to see packets that are sent and received.

Communications trace can be used for troubleshooting both IPv4 and IPv6 communications.

Use communications trace in these situations:

• Your problem analysis procedures do not give enough information about the problem.

• You suspect that a protocol violation is the problem.

• You suspect that line noise is the problem.

• You want to know if your application is transmitting information correctly across the network.

• You want to know if you have performance problems with network congestion or data throughput.

To use the CL commands to perform a communications trace, have *SERVICE special authority, or be authorized to the service trace function of i5/OS through iSeries™ Navigator. See the chapter on user profiles in iSeries Security Reference for more information about this type of authority.

The trace connection function is an alternative method of getting a trace that is similar to a communications trace. See Trace connection for more information.

To use the communications trace function, perform these tasks.

1. Planning a communications trace
   You need to prepare for the communications trace before using it to determine whether your data is being transmitted correctly across the network.
2. Performing a communications trace
   You can use CL commands in the character-based interface to perform a communications trace. If you want to start a new trace on the same line, first delete the existing communications trace.
3. Tools for analyzing a communication trace
   The Communications Trace Analyzer is designed to analyze a communications trace using either the Start Communications Trace (STRCMNTRC) command or the Trace Connection (TRCCNN) command for various performance, connection, or security problems.
4. Additional communications trace functions
   The Check Communications Trace (CHKCMNTRC) command and Check Communications Trace (QSCCHKCT) API provide additional communications trace functions.

Parent topic:

Related concepts
Trace connection