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The Tracing Facility

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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: NMTCnnnn.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.

NOTE: Although the format of the default trace file name is the same for all types of tracing, the same default file name will not be assigned for more than one trace. This is because the default trace file name is automatically assigned in numerical order. For example, suppose the last default trace file name assigned was NMTC0004.PUB.SYS. If you started SNA Transport intrinsic tracing, and did not specify a trace file name, the default name NMTC0005.PUB.SYS would be assigned. Then, if you started SNA Transport node tracing without specifying a trace file name, the default name NMTC0006.PUB.SYS would be assigned. Finally, if you started link-level tracing, and did not specify a file name, the default name NMTC0007.PUB.SYS would be assigned.

Remember, this applies only when you are using the default file-naming scheme.

Node Tracing

Node tracing records state transitions and events internal to SNA Transport for each SNA node (PU-SSCP, LU-SSCP, and a portion of LU-LU traffic). It is turned on with the NODETRACE parameter of the SNACONTROL START MPE command. Once node tracing is active, it remains active until the link is brought down with the SNACONTROL STOP command. Node tracing is written to a disk file.

SNA Transport tracing is not normally necessary unless recommended by the HP systems engineer for special problem-solving.

The trace file name can be specified as an argument to the NODETRACE 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: NMTCnnnn.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.

NOTE: Although the format of the default trace file name is the same for all types of tracing, the same default file name will not be assigned for more than one trace. This is because the default trace file name is automatically assigned in numerical order. For example, suppose the last default trace file name assigned was NMTC0004.PUB.SYS. If you started SNA Transport intrinsic tracing, and did not specify a trace file name, the default name NMTC0005.PUB.SYS would be assigned. Then, if you started SNA Transport node tracing without specifying a trace file name, the default name NMTC0006.PUB.SYS would be assigned. Finally, if you started link-level tracing, and did not specify a file name, the default name NMTC0007.PUB.SYS would be assigned.

Remember, this applies only when you are using the default file-naming scheme.

Link-Level Tracing

The data link-level protocol is traced by the link driver (for the SDLC and token ring links) and the module configurator (for the X.25 link). Link-level tracing is turned on with the LINKTRACE parameter of the SNACONTROL START or SNACONTROL TRACEON MPE command, and off with the SNACONTROL STOP command or the LINKTRACE parameter of the SNACONTROL TRACEOFF command. Link-level tracing has two options: trace all bytes of each link frame (full tracing), and trace only the first 16 bytes of each link frame (partial tracing). Since full tracing uses more resources, partial tracing is the recommended default. Link-level trace output is written to a disk file.

We recommend that you use link-level tracing only for problem-solving purposes when requested by the HP systems engineer.

The trace file name can be specified as an argument to the LINKTRACE parameter when tracing is started. 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). Note that if you start link-level tracing with the SNACONTROL START command, and specify a name for the trace file, the file must be written to the SYS account. That is, if you specify an account name within the trace file name, it must be SYS. If you do not specify an account name, the file will automatically be written to the SYS account. This applies only when link-level tracing is started with the SNACONTROL START command.

You also can let the default name be assigned: NMTCnnnn.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 examples of the SDLC link and X.25 link tracing formats) is described later in this chapter. More-detailed information about NMDUMP is contained in Using the Node Management Services Utilities.

NOTE: Although the format of the default trace file name is the same for all types of tracing, the same default file name will not be assigned for more than one trace. This is because the default trace file name is automatically assigned in numerical order. For example, suppose the last default trace file name assigned was NMTC0004.PUB.SYS. If you started SNA Transport intrinsic tracing, and did not specify a trace file name, the default name NMTC0005.PUB.SYS would be assigned. Then, if you started SNA Transport node tracing without specifying a trace file name, the default name NMTC0006.PUB.SYS would be assigned. Finally, if you started link-level tracing, and did not specify a file name, the default name NMTC0007.PUB.SYS would be assigned.

Remember, this applies only when you are using the default file-naming scheme.



Chapter 5 SNA Link Troubleshooting

The Logging Facility