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

112 Chapter3
NetIPC Intrinsics
IPCRECVCN
Protocol-Specific Considerations
The following Table 3-9 outlines parameters that are specific to the
particular protocol you are accessing.
X.25 Considerations
IPCRECVCN is used with switched virtual circuits (SVCs) only.
The call user data field returned in the
opt parameter (code=5) is used
by X.25 as follows. The first four bytes of the call user data field is used
to determine the destination call (source) socket. The incoming call is
sent to the call socket whose relative protocol address matches the first
four bytes of the call user data. See the discussion for IPCCREATE for
more information on protocol relative addresses.
Call acceptance can be affected by the X.25 configuration of the security
field in the SVC path table which can limit access to a node by
specifying which remote X.25 addresses are allowed to communicate
with the node. See the X.25 XL System Access Configuration Guide for
more information about security features.
Table 3-9 IPCRECVCN Protocol Specific Parameters
Parameters TCP X.25
flags
0 Protected connection n/a
21 Enable checksum n/a
25 n/a Discarded
opt
3 Maximum send size n/a
4 Maximum receive size n/a
5 n/a Received CUD
141 Calling node’s IP
address
Calling node’s X.25
address
144 n/a Bit 7:fast select
Bit 8: fast select
restricted
Bit 14: PAD
Bit 16: calling node
address available flag
145 n/a Facility field