A trace file is used to search for and correct errors. It logs in detail - the higher the trace level (see Option -V<tracelev>), the more detailed the information - what SAProuter does. From this, you can see in which function an error occurred, why a connection was not established, etc.

When you start SAProuter, you can specify a trace file:

UNIX/NT: saprouter -r -T <tracefile>
AS/400: saprouter '-r -T <tracefile>'

A trace file always exists. If the option is not used, the trace file dev_rout in the working directory is used. It resides in the working directory of the SAProuter.