Working with a communications trace

You can start or stop a communication line trace on a configuration object.

After you run the trace, the data can be formatted. You can view the formatted data by printing it.

You can use communications trace for the following situations:
  • To isolate errors that you cannot isolate by using the communications verification procedure
  • To collect more data when the problem analysis procedures do not provide enough information on the problem
  • If you suspect a violation of the communications protocol or some other communications line problem
  • If you suspect line noise
  • When the error messages indicate that there is an SNA BIND problem

Running and interpreting the communications trace requires detailed knowledge of communications protocols. To obtain the most accurate sample of your line status, whenever possible, start the communications trace before you vary on the lines.

Note: Use the online help from the Work with Communications Trace display to view a list of protocols.

Options and function keys

The Work with Communications Traces display has the following options and function keys:
  • Start trace (F6)

    This function key starts the tracing of the data on a communications configuration object. The Start Trace display appears after you press this function key. For more information, see Starting a communications trace.

  • Stop trace (option 2)

    This option appears only on the Work with Communications Traces display. With this option, you can end the trace and stop collecting data. A trace must be stopped before you can format, print, or delete the data. To ensure that the trace is stopped, press the Refresh function key and check the Trace Status field.

  • Delete trace (option 4)

    The trace must be stopped (option 2) before you can use this option. Select this option to delete the trace information when you no longer need the data. Traces are not automatically deleted when you leave a communications trace function. This option releases system space so that you can start other traces without having to increase the maximum amount of storage that is provided for the communications trace. Traces that are not deleted are listed on the Work with Communications Traces display.

  • Format and print trace (option 6)

    Use this option to format and print the trace. For more information about this option, see page Format and print trace.

  • Display message (option 7)

    Use this option to view a message that indicates the status of the trace that stopped because of an error.

  • Restart trace (option 8)

    Use this option to start a trace that stopped.

  • Change size (F10)

    Use this function key to change the amount of storage that all traces use. You might want to increase the amount of storage, if your system has many active traces or traces that will be active for a long time.

  • Display buffer size or display trace status (F11)

    With this function key, you can select and alternate between buffer size and trace status.

  • Refresh (F5)

    This function key updates the data on the display.

Status conditions

After the Work with communications trace option is selected from the Start a Service Tool display, the Work with Communications Traces display is shown.
Figure 1. Example of the Work with Communications Trace display
                        Work with Communications Traces
 
Type choice, press Enter.
2=Stop trace          4=Delete trace   6=Format and print trace
7=Display message     8=Restart trace
 
Configuration
Opt     Object       Type   Trace Description       Protocol   Trace Status
_     LosAngeles    Line   Test LosAngeles Line    SDLC       Active
_     Mpls          NWI    Test Mpls               ISDN       Stopped
_     Tucson        Line   Test Tucson Line        ASYNC      Waiting
 
 
 
 
 
 
 
 
 
 
F3=Exit    F5=Refresh      F6=Start trace   F10=Change size
F11=Display buffer size    F12=Cancel

Details of the trace, including status, are displayed. The trace status can be one of the following options:

Condition description

Waiting
The trace is waiting for the configuration object to be varied on (not collecting data).
Active
The trace data is being collected.
Stopping
The trace is stopping.
Stopped
The trace stopped (not collecting data).
Error
An error occurred on the configuration object while the trace was collecting data. The data might or might not be collected. The trace stopped.
Starting
The trace is being started by another user. You cannot stop or delete this trace.
Formatting
Trace is being formatted.

Starting a communications trace

An example of a Start Trace display follows. 
                                   Start Trace
 Configuration object . . . . . . . . .  _________
 
Type . . . . . . . . . . . . . . . . .  1  1=Line  2=Network interface
3=Network server
 
Trace description  . . . . . . . . . .  ____________________
 
Buffer size (in kilobytes) . . . . . .  1  1=128, 2=256, 3=2M, 4=4M,
                                           5=6M, 6=8M, 7=16M, 8=32M, 9=64M
 
Stop on buffer full  . . . . . . . . .  N  Y=Yes, N=No
 
Data direction   . . . . . . . . . . .  3  1=Sent, 2=Received, 3=Both
 
Number of bytes to trace
Beginning bytes  . . . . . . . . . .  *CALC  VALUE, *CALC
Ending bytes   . . . . . . . . . . .  *CALC  VALUE, *CALC
 
Type choices, press Enter.  
 
F3=Exit   F5=Refresh   F12=Cancel
Enter the name of a communications configuration object description in the Configuration object field.

Describe the trace in the Trace description field. This field can help you identify the trace.

You can select a buffer size to hold the communications data that the trace collects. The default buffer size is 1=128 KB. Base the size of the buffer on the speed of the communications line and on the amount of time necessary to trace the data. For high-speed lines or long periods of tracing, use a larger buffer size.

If you specify Yes in the field, the trace stops when the buffer is full. This option is useful for viewing the initial data that is coming across a line. If you specify No, the trace continues until you stop it. In this case, the data in the buffer is written over each time the buffer is full.

You can select the direction of data to be traced by specifying one of the three selections in the Data direction field:
  • Only data that the system is sending (option 1)
  • Only data that the system is receiving (option 2)
  • Both the data that is sent and received by the system (option 3)
Note: If you specify option 1 (Sent) for lines that are in SDLC short-hold mode, the trace does not include controller names.

You can select how much data is traced in a frame of data. The value that is entered is the amount that is saved as part of the trace. The minimum value that is allowed for both the beginning and the end value is 36 bytes. Those 36-byte minimum values include the protocol header. The configuration object that you are tracing determines the maximum value that is allowed.

Notes:
  1. The BSC protocol ignores the beginning and ending byte values.
  2. The SDLC, high-level data link control (HDLC), X.25, frame relay, Ethernet, distributed data interface (DDI), ATM, and token-ring protocols ignore the ending byte value.
  3. The minimum value that is allowed for the beginning byte value for local area network (LAN) protocols (including frame relay protocols and ATM protocols) is 72 bytes.

When all required options are complete, press the Enter key. The Work with Communications Trace display is shown.

If the communications object being traced is in varied off status when you start the trace, the trace remains in waiting status until you vary on the communications object. If the object is varied on, the trace immediately goes to the active state, and the system collects trace data.

The trace remains active until one of the following occurs:
  • You select the option to stop the trace on the Work with Communications Traces display.
  • You vary off the configuration object that is being traced.
  • The configuration object that is being traced has an error.
  • The trace buffer is full, and the option to stop on buffer full was selected.
Note: You can exit the communications trace function to do other work while the trace is active.

Traces are not automatically deleted when you exit a communications trace function. To return to the communications trace, complete the following steps:

  1. Select the Start a service tool option from the service tools (SST or DST) display.
  2. Select the Work with communications traces option.
  3. From the Work with Communications Traces display, you can check the status of the trace or select to stop the trace.

Format and print trace

You must select the Stop Trace option before you format or print the trace. With the Format and print trace option, you can select various formatting options and prepare the trace data for printing. The options vary for each protocol. An example of the Format Trace Data display follows.
Figure 2. Example of Format a Trace Data display
                                  Format Trace Data
 
Configuration object . . . . . .  TRNLINE
 
Type . . . . . . . . . . . . . .  LINE
 
Type choices, press Enter.
 
Controller . . . . . . . . . .  *ALL      *ALL, name
 
Data representation  . . . . .  3           1=ASCII, 2=EBCDIC, 3=*CALC
 
Format RR, RNR commands  . . .  N           Y=Yes, N=No
 
Format Broadcast data  . . . .  Y           Y=Yes, N=No
 
Format MAC or SMT data only. .  N           Y=Yes, N=No
 
Format UI data only  . . . . .  N           Y=Yes, N=No
 
Format TCP/IP data only  . . .  N           Y=Yes, N=No
 
 
F3=Exit   F5=Refresh    F12=Cancel
Notes:
  1. To view all the data that is associated with the trace, press the Enter key without changing to the default values on the Format a Trace Data display. The information is not in any special format.
  2. Select the option to format and print only the data that you want to see.
  3. All options available for formatting depend on the protocol of the line that is being traced. Only valid choices are shown for each protocol.
  4. Not all combinations of options are valid for all protocols. If you select an option that is not valid, messages appear. If an error message appears, you must change your selections. Press F5 (Refresh) function key to restore all options to their default values.
  5. For more information about these options, use online help.

When the format of the trace data is complete, the output can be printed on the console printer (the printer that is attached to the same I/O processor as the console). Only SCS-type data streams are supported.

The format of the trace data follows:
  • An introduction page that contains, for example, configuration object, type, protocol, start and stop dates and times, trace options, and formatting options.
  • A help page to help you understand the output. Help information for a specific protocol is given because the trace data differs for each communications protocol.
The formatted output is shown as follows.
Figure 3. Example of formatted trace data output for SDLC
  Record       Data    Record    Record           Data    Controller              Number   Number    Poll/
 Number  S/R  Length  Status    Timer            Type    Name/Number    Command  Sent     Received  Final
 ------  ---  ------  --------  ---------------  ------  -------------  -------  ------   --------  -----
      7   R       69  00000000  12:29:56.72963   EBCDIC  ZSDLLC30  /01   XID                         ON
         Data . . . . . :  3245056150080000 0084C00000000000  01010B0000010900 00000007000E0DF4   *.&;...D{....................4*
                           DADBCC4BDACBCDCE EFCGC5F31017F116  1101130011F9F4F0 F6F5F0F0F1F0F1F0   *ABC.ABCDEFG..1......94065001010*
                           C4C6C44040                                                             *DFD                             *
      8   S        0  00000000  12:29:56.76081   EBCDIC  ABCLLC30  /01   SNRM                        ON
      9   R        0  00000000  12:29:56.78450   EBCDIC  ABCLLC30  /01   UA                          ON
     52   S      110  00000000  12:29:57.76210   EBCDIC  ABCLLC30  /01   I           0         0     ON
         Data . . . . . :  2D00010200006B81 0031001307B0B051  3107878686870706 0200000000000000   *......,A..........GFFG..........*
                           944300000CDADBCC 4BEAEBCCD3D3C4F3  F02E000902E2D5C1 E2E5C3D4C7090300   *M....ABC.AABCLLD30....SNASVCMG...*
                           00BCF9CAD600000D 04DADBCC4BEAEBCC  D3D3C4F3F00A1300 7B00BCF9CAD60000   *..9.O....ABC.ABCLLD30...#..9.O..*
                           000CDADBCC4BEAEB CCD3D3C4F4F0                                          *..ABC.ABCLLD40                  *
     53   R      110  00000000  12:29:57.80065   EBCDIC  ABCLLC30  /01   I           0         1     ON
         Data . . . . . :  2F00010200006B81 0031001307B0B051  3107878686870706 0200000000000000   *......,A..........GFFG..........*
                           944300000CDADBCC 4BEAEBCCD3D3C4F4  F02E000902E2D5C1 E2E5C3D4C7090300   *M....ABC.ABCLLD40....SNASVCMG...*
                           00BCF9D56600000D 04DADBCC4BEAEBCC  D3D3C4F4F00A1300 7B00BCF9D5660000   *..9N.....ABC.ABCLLD40...#..9N...*
                           000CDADBCC4BEAEB CCD3D3C4F3F0                                          *..ABC.ABCLLD30                  *
 * * * * *   E N D   O F   E X A M P L E   P R I N T O U T   * * * * *

The width of the file is 132 characters. The data is in hexadecimal representation and either American National Standard Code for Information Interchange (ASCII) or EBCDIC character representation. The columns of the trace output that are common to all protocols follows:

Record number
The number of the trace record shows if the record type is sent (S) or received (R).
Notes:
  1. The letter C in this column indicates that an X.21 short-hold mode connection was cleared.
  2. If an M is shown, a modem change occurred.
Data length
The amount of data, in decimal, that the record contains.
Record status
The protocol-dependent return code for the trace record. The value 00000000 is successful; no errors were found. Other return codes are listed in the functional specification for the protocol that is running or in the port manager.
Record timer
The time that each event occurs. Depending on the communications hardware that is being used, the record timer is one of the following values:
  1. A time of day value, HH:MM:SS.NNNNN (where H=hours, M=minutes, S=seconds, and N=subseconds), based on the system time when the trace was stopped.
  2. A relative time in decimal seconds. This timer value provides the relative time between events.
Data type
Shows whether the traced data is printed in ASCII or EBCDIC character representation. If the character representation of the data is mostly periods, you might want to format the data again by using the other option for data representation.
Controller name/number
Indicates which controller originated the frame or record. In some conditions, this data is not available, and the column remains blank.
Note: The formatted trace output is not security protected. Customer passwords are shown when they cross communications lines.