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

Chapter 1 37
NetIPC Fundamentals
Direct Access to Level 3 (X.25)
Figure 1-11 SVC Server Processing Example
Permanent Virtual Circuits (PVCs)
Permanent virtual circuits are defined as two DTEs with a logical
association permanently held by the network. Since the connection is
permanent, both processes must initiate the connection using the
IPCCREATE intrinsic. Both processes must specify the destination of a
connection request with the IPCDEST intrinsic which requires a node
name corresponding to a configured PVC number.
The possible ordering of intrinsic calls to communicate over a PVC
could be as follows:
1. Create a call socket with IPCCREATE. The call socket descriptor
(
calldesc ) is returned.
2. Create a destination descriptor socket (
destdesc ) with IPCDEST.
3. Establish the virtual circuit socket with IPCCONNECT, supplying the
calldesc and destdesc created by the previous two calls.
4. Send a reset packet (to the DCE) by setting the reset request in
IPCCONTROL.
5. Send an interrupt packet to the remote process by setting the
interrupt request in IPCCONTROL.
6. Send data over the connection with IPCSEND.
7. Receive data over the connection with IPCRECV.
8. Send a reset packet by setting the reset request in IPCCONTROL
when all data has been sent/received.
9. Shutdown the connection with IPCSHUTDOWN. Note that a PVC is a
permanent connection, and the shutdown process releases the
resources associated with the connection.
1) IPCCreate
2) IPCRecvcn 4) IPCRecv 5) IPCSend 6) IPCRecv 7) IPCShutdown
CALL
ACCEPTED
CLEAR
REQUEST
CLEAR
CONF
DATA
DATA
X.25 Protocol
3)
INCOMING
CALL
REQUEST