[ Previous | Next | Contents | Search ]
AIXLink/X.25 1.1 for AIX: Guide and Reference

Appendix D. CCITT Causes and Diagnositics

The following information includes the X.25 clear and reset causes and diagnostic codes as defined by the CCITT.

X.25 Clear and Reset Codes

Each clear-indication or reset-indication packet includes a 1-byte cause code and a 1-byte diagnostic code in the received data. The API subroutines take no specific action on any of the cause or diagnostic codes.

Origins of the Clear or Reset

X.25 clear-indication and reset-indication packets may be generated by the X.25 code, the remote data terminal equipment (DTE), or the X.25 network itself. The relationship between cause codes and diagnostic codes is shown in a table in the annexes to ISO 8208. The following sections discuss X.25 clear and reset codes:

CCITT Restart Causes

The CCITT meanings for the restart cause codes are:

Hex Meaning
00 Originated by the remote X.25 data terminal equipment (DTE).
01 Local procedure error.
03 Network congestion.
07 Network up.

X.25 Logical Channel States

This information lists the CCITT logical channel states referred to in "X.25 Diagnostic Codes".

State Meaning
d1 Flow control ready.
d2 DTE reset request.
d3 DCE reset indication.
p1 Channel ready.
p2 DTE call request.
p3 DCE incoming call.
p4 Data transfer.
p5 Call collision.
p6 DTE clear request.
p7 DCE clear indication.
r1 Packet level ready.
r2 DTE restart request.
r3 DCE restart indication.

X.25 Diagnostic Codes

Diagnostic codes give additional information about the reason for sending a clear-indication or reset-indication. (The reason is also indicated in the cause code.) The meaning of each diagnostic code depends on whether X.25 is being used as a medium for SNA communications, by means of qualified logical link control (QLLC), or being used directly. If SNA is being used, refer to the "SNA Diagnostic Codes"; if X.25 is being used directly, refer to the "CCITT/ISO Diagnostic Codes" that follows.

In addition, some diagnostic codes are used by the xtalk command.

[ Previous | Next | Contents | Search ]