Migrating X.25 over PSI to X.25 over TCP/IP (XOT)

2 X.25 Overview
The HP-UX X.25 link solution provides the hardware and software components that enable HP
9000 systems and Integrity systems to communicate with other HP and non-HP systems over X.25
packet switching networks.
The X.25 link implements the CCITT X.25 Recommendations and includes the components necessary
to connect HP 9000 systems and Integrity systems to a public or private packet switching network
or to another system in a back-to-back configuration that conforms to the CCITT X.25
Recommendations (1980, 1984 or 1988).
The CCITT X.25 Recommendations specify the protocols to be used between a Data Terminal
Equipment (DTE) and a Data Circuit terminating Equipment (DCE) in a Packet Switched Public Data
Network (PSPDN), when accessed by a dedicated circuit.
HP-UX X.25 provides X.25 CCITT Socket APIs to write user applications. It also supports IP datagram
transmission on the X.25 protocol. The X.25 architecture implements three layers of the OSI model.
The three layers in the X.25 architecture are the physical layer, the data link layer, and the packet
layer. Figure 1 illustrates the X.25 architecture.
Figure 1 X.25 Link Architecture
5