HP X.25/9000 Programmer's Guide

36 Chapter3

Establishing and Terminating a Socket Connection

Connection Establishment for the Client Process

NOTE The ﬁrst initialized interface is the one that is ﬁrst initialized when the

sub-system is restarted after all cards are stopped.

You can use the

x25ifname

ﬁeld to control performance. Each interface

used to connect to a particular network can only support a ﬁxed number

of circuits. When selecting the network interface you should also

consider bandwidth, throughput, and response-time factors.

NOTE Facilities such as call user data (or the circuit’s D bit) must be speciﬁed

before issuing the connect() call. Facilities are speciﬁed with

ioctl(X25_WR_FACILITIES), and call user data is speciﬁed with

ioctl(X25_WR_USER_DATA). The D bit can be set with

ioctl(X25_SEND_TYPE). These ioctl() calls are described in the

following chapters.

If the client and server are using protocol IDs for address matching prior

to issuing the connect() call, the client must specify the server's

protocol ID with the ioctl(X25_WR_USER_DATA) call (see “The

ioctl(X25_WR_USER_DATA) Call” in Chapter 5). The example below

describes how to use ioctl(X25_WR_USER_DATA) to specify a remote

protocol ID.

Example (client specifying the protocol ID)

The example below shows the system calls a client must execute if the

protocol ID is to be speciﬁed in the CALL REQUEST packet.

/* put the protocol ID in the call-user data field */

struct x25_userdata userdata;

...

userdata.x25_cud_len = 1; /* one byte for PID */

userdata.x25_cu_data[0] = 0x05; /*PID is 0x05 */

result = ioctl(s, X25_WR_USER_DATA, &userdata);

...

result = connect (s, &peeraddr, sizeof(struct x25addrstr));

Refer to the connect(2) entry in your man pages for more information.

36960-90061.bk Page 36 Friday, November 10, 2000 3:42 PM