SNA Link/iX Node Managers Guide (30291-90507)

112 Chapter5
SNA Link Troubleshooting
The Tracing Facility
The Tracing Facility
Tracing provides data for analysis, and can be done on many levels. The
highest level of tracing is at the services level (see the Node Manager’s
Guide for each service for which tracing is available). SNA tracing is
done at the SNA Transport level (an intermediate level) and at the link
level (the lowest level). All of these functions are controlled through
MPE commands (see Chapter 6 , “MPE Commands,” in this manual).
SNA Transport Tracing
The tracing facility for SNA Transport performs two types of tracing:
intrinsic tracing and node tracing.
Intrinsic Tracing
Intrinsic tracing records the interface between SNA Transport and the
SNA services (LU-LU traffic). The interface consists of procedure calls
to the SNA Transport intrinsics. These procedures are used to establish
and maintain user sessions. Intrinsic tracing is turned on with the
INTRINSIC parameter of the SNACONTROL TRACEON MPE command, and
off with the INTRINSIC parameter of the SNACONTROL TRACEOFF
command. (It also is stopped when the link is brought down with the
SNACONTROL STOP command.) Intrinsic tracing is written to a disk file.
The trace file name can be specified as an argument to the INTRINSIC
parameter when tracing is turned on. Naming the file this way allows
the contents of the file to be overwritten each time a new trace is
started (no warning is issued). Or you can let the default name be
assigned: NMTC
nnnn .PUB.SYS, where nnnn is a number from 0000
through 9999.
NOTE Regardless of whether you specify a trace file name or let the default
name be assigned, the trace file that is opened when tracing is started
is used until tracing is stopped. This means that if the file becomes full
before tracing is stopped, the current contents of the file are
overwritten with the new trace information, starting at the beginning
of the file (no warning is issued). You should keep this in mind if you
usually run tracing for long periods without stopping. If you want to
keep the contents of a trace file from being written over, stop tracing
before the file is full, and then restart it.
The trace file can be formatted through the NMDUMP utility. Using
NMDUMP for SNA links (including an example of the SNA Transport
tracing format) is described later in this chapter. More-detailed
information about NMDUMP is contained in Using the Node
Management Services Utilities.