NetIPC 3000/XL Programmer's Reference Manual (5958-8600)

Chapter 1 43
NetIPC Fundamentals
Direct Access to Level 3 (X.25)
Access to X.25 Protocol Features
The NetIPC intrinsics provide access to the following X.25 protocol
features:
• Send and receive interrupt and reset packets.
You can request the X.25 protocol to send an interrupt or reset
packet with IPCCONTROL. When used in this way, the IPCCONTROL
intrinsic will not return until the appropriate confirmation packet is
received by X.25.
• Set no activity timeout.
You can set a no activity timeout value with the IPCCONTROL
intrinsic. This option clears the connection after the specified time if
no data packets are exchanged on the virtual circuit.
• Qualifying X.25 data packets.
The Q bit in the general format identifier field in an X.25 data
packet can be set using the IPCSEND intrinsic. The status of the Q bit
in incoming data packets is returned in the IPCRECV intrinsic. The
Q bit status can be used to indicate whether the data is a user
message (Q bit=0) or a device control message (Q bit=1) from or to a
remote PAD.
• Set end-to-end acknowledgment.
The D bit in the general format identifier field in an X.25 data
packet can be set using the IPCSEND intrinsic. The status of the D bit
in incoming data packets is returned in the IPCRECV intrinsic.
Setting the D bit locally specifies end-to-end acknowledgment of data
packets. IPCSEND does not complete until it receives
acknowledgment that the entire message has been received. For
HP 3000 to HP 3000 communication, IPCRECV initiates the
acknowledgment when the remote HP 3000 process has received the
entire message.
• Set cause and diagnostic codes.
Using IPCSHUTDOWN, you can enter a reason code that will be
included in X.25 clear packets as cause and diagnostic values. This
option is only used with SVCs. Reasons for events or errors are
returned by IPCCONTROL. See Appendix B , “Cause and Diagnostic
Codes,” for a list of diagnostic codes used with X.25 protocol access.
Note that when the DTE sends the clear packet, the cause code is
always set to zero.