HP X.25/9000 Programmer's Guide

Chapter 2 23

X.25 Addressing

Address Space Conﬂicts

The X.25 subsystem’s programming access prevents any two sockets

from binding to the same address structure. When a bind() call is made,

the subsystem checks the speciﬁed address against addresses that are

already associated with the socket. The bind() call is rejected if there is

a conﬂict in the space allocation of components in the address structure.

The address structure is composed of three components:

• Interface name – the name of the interface or port

• Address/subaddress – the X.121 addresses

• PID – the Protocol Identiﬁcation number

Address conﬂicts occur with bind() calls when the speciﬁed address

structure occupies or overlaps into an address region that has already

been assigned to another socket. In this instance, the system returns one

of two errors:

• EADDRNOTAVAIL – is returned when all of the addresses speciﬁed

in the bind() call includeall of the addresses speciﬁed ina previously

bound socket.

• EADDRINUSE – is returned when the addresses speciﬁed in the bind

include some of the addresses speciﬁed in a previously bound socket.

How to Avoid Address Conﬂicts

Avoid wildcard addresses with “*”, and be cautious of all wildcard

Table 2-4 Addressing Conﬂict Errors

Previous Bind Current Bind errno value

123* 12* EADDRNOTAVAIL

12* 123* EADDRINUSE

1?3* 123* EADDRINUSE

123* 1?3? EADDRNOTAVAIL

36960-90061.bk Page 23 Friday, November 10, 2000 3:42 PM