The OSAENTA trace process

Trace data is collected as frames enter or leave an OSA adapter for a connected host. The actual collection occurs within the device drivers of OSA cards, capturing the data at the point where it has just been received from or sent to the network.

Frames that are captured have extra information added to them before they are stored. This extra information, such as timestamps, is used during the packet formatting. The captured data reflects exactly what the network sees. For example, the trace contains the constituent packets of a fragmented packet exactly as they are received or sent.

The selection criteria for choosing packets to trace are specified through the OSAENTA statement or OSAENTA command. See z/OS Communications Server: IP Configuration Reference for more information about the OSAENTA statement and see z/OS Communications Server: IP System Administrator's Commands for more information about the OSAENTA command.

The OSAENTA trace can have performance implications if you do not specify sufficient trace filters before enabling the trace. OSAENTA can reduce the amount of traffic the OSA-Express® feature can process and the amount of traffic that can be accelerated through that OSA-Express. Also, host processing to collect the OSAENTA trace records can increase host CPU consumption. Specify sufficient filters to limit the amount of traffic that is traced to only what is necessary for problem diagnosis.

Figure 1 illustrates the overall control and data flow in the OSAENTA tracing facility.