X25AM Configuration and Management Manual

PTrace for the X25AM Subsystem
X25AM Configuration and Management Manual—523424-004
6-9
FIND Command
FIND Command
The FIND command can be very useful for reading X25AM traces. In general, you look
for problems from the higher levels to the lower levels. The three major components of
the X25AM environment are:
•
Level 4 (the application level, with programmatic calls such as READ and WRITE)
•
Level 3 (the packet level)
•
Level 2 (the bit-synchronous frames and modem signals)
If the program is receiving spurious error 140s, take a trace of the problem. Then use
PTrace, SELECT (L3,L4), and the FIND command to look for the string “140”(FIND
“140”). After you find the error, look at the preceding packets to discover its cause. You
may find that the application has not opened the subdevice or that the subdevice was
configured with an incorrect address or port number.
X25AM traces the WRITELINK as well, so you can look for errors using FIND “FE#” in
PTrace. Whenever X25AM returns an error that is not FEOK (0) to an application,
PTrace shows it as a level-4 trace record with “FE #”. Thus, you can easily find all the
errors in PTrace by entering >FIND “FE #”. If there is more than one error, enter F
again to find the rest.
If level 3 can successfully send and receive packets, then there is probably no error on
level 2 (a level-2 data, or I-FRAME always contains a level-3 packet). In this case, you
can scan the traces more quickly by masking off the level-2 trace mask.
Tracing Level 2
The type of CLIP that you use determines how the level-2 protocol is implemented; the
tracing is different as a result of the CLIP. The CLIP can do the busywork prescribed by
the protocol and interrupt the host CPU only when actual data arrives or a significant
event (such as a line error) occurs. To view the relationship of level 2 to the protocol,
set your PTrace select mask for the trace type records shown in Table 6-3
.
What to Look for in Level 2
When you use the SCF START command on an X25AM line, level 2 becomes active.
When you issue the START command, a message is sent to the console: “X.25 LINE
READY.” If you see a “LINE NOT READY” error on the console instead, then you
Table 6-3. PTrace Select Masks
PTrace Mask
SELECT L2
SELECT CLIPDI
SELECT CLIPDO