# dectrace overview

dectrace decodes and displays messages sent or received by the NMS ISDN protocol stack that were previously captured in a log file by the board monitoring utility (oammon).

dectrace decodes:

- Q.931/Q.921 messages sent or received by the stack when the stack is running in any mode.

- ACU primitives exchanged by the application and the stack when the stack is running in ACU stack mode.

Note: By default, the log file does not contain stack message data. To provide data in this file that dectrace can process, the agtrace, itrace, or both utilities must be used. For details, see Creating a log file for dectrace.

#### Usage

dectrace [-f srcfile] [-d tmask] [-b brdno] [-a nai] [-g grp] [-c clrf]

where:

Option | Meaning | Default
--- | --- | ---
-a nai | Decodes only the messages on the specified NAI. | All NAIs.
-b brdno | Decodes only the messages from or to board brdno. | All boards.
-c clrf | Decodes only the messages with call reference clrf. | All call references.
-d tmask | Provides a decoding mask for Q.931 decoding. See tmask values. | TIME STAMP + MESSAGE + CALL_REF + IE + IE CONT + ISDN_MSG
-f srcfile | Specifies the file to be decoded. | agerror.log
-g grp | Decodes only the messages for the specified NFAS group. | All NFAS groups.

The following table lists the valid tmask values:

Mask | Mnemonic | Description
--- | --- | ---
8000 | BUFFER | Prints the whole hexadecimal buffer.
2000 | PROTOCOL DISC | Decodes the protocol discriminator.
1000 | CALL REF | Decodes the call reference.
0800 | MESSAGE | Decodes the message type.
0400 | INFO ELEM | Decodes the information element ID.
0200 | INFO ELEM CONT | Decodes the data contents of the IE.
0100 | DATA LINK | Decodes the commands or events at the DL interface.
0080 | TIME STAMP | Includes a time stamp before the messages.
0008 | ISDN_MSG | Decodes the ISDN messages.
0004 | ACU_MSG | Decodes the ACU messages.
0002 | TRACE_PH | Decodes PH primitives.