X25AM Configuration and Management Manual

X25AM Configuration and Management Manual—523424-004

2-1

Overview of the X25AM Subsystem

This section provides a brief introduction to the X25AM communications subsystem

and describes the various configuration and monitoring programs that can be used with

the X25AM product.

Introduction to the X25AM Subsystem

The X25AM communications subsystem connects Integrity NonStop NS-series or

NonStop S-series servers to public or private packet switching data networks (PSDNs)

or other computer systems using the X.25 standard set of networking conventions.

The X25AM subsystem works with any public or private PSDN that supports the 1980

or 1984 ITU-T X.25 Recommendations. X25AM has been certified for use with many

public networks around the world, including all those operated by European countries

that require certification of access software.

The X25AM subsystem supports Link Access Procedure-Balanced (LAPB), the

Data-Link Layer procedure generally used for X.25 connections. LAPB allows a

point-to-point connection between two stations, where each station can establish and

disconnect the link and initiate data transfers.

The X25AM subsystem can be configured for either data circuit-terminating equipment

(DCE) or data terminal equipment (DTE) operation, allowing

NonStop Integrity NS-series or NonStop S-series servers to be used as either end of a

switched or leased-line X.25 connection.

Subsystem Components

The X25AM subsystem consists of the following components (Figure 2-1 on page 2-3).

X25AM I/O Process

An X25AM I/O process is a program, running on an Integrity NonStop NS-series or

NonStop S-series server, that controls an X25AM line and all its subdevices. One

X25AM I/O process is required for each X25AM line; multiple lines require multiple

X25AM I/O processes.

Applications communicate with remote entities in a network by means of an X25AM I/O

process through file-system procedures. Other processes (including other HP

products) can also communicate with an X25AM I/O process for different types of

connectivity.

Multiple applications or other processes can communicate with a single X25AM I/O

process. For example, an Expand process, a SNAX process, and multiple user