X25AM Configuration and Management Manual

Overview of the X25AM Subsystem
X25AM Configuration and Management Manual—523424-004
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X25AM Line
applications can all communicate through a single X25AM I/O process and a single
X25AM line.
An X25AM I/O process is configured as a device using Subsystem Control Facility
(SCF) commands to the WAN subsystem. When you configure an X25AM I/O process,
you can specify basic line characteristics (subscription parameters), such as circuits,
timers, retries, frame size, default window size, default packet size, default throughput
class, and extended packet sequencing capability.
Detailed information about configuring X25AM I/O processes is provided throughout
this manual.
X25AM Line
X25AM lines can theoretically be configured for up to 510 circuits (510 subdevices). An
X25AM line, capable of supporting X.25 communications, is a physical entity attached
to a SWAN/SWAN 2 concentrator. A line is configured and controlled by its X25AM I/O
process.
When you configure an X25AM I/O process for a line you specify the number of circuits
for the line; the number of circuits determines the number of subdevices you can add
to each line. Each circuit can be used for call activity and is associated with a single
subdevice.
You use SCF commands to the X25AM subsystem to start, stop, alter, and monitor
X25AM lines.
X25AM Subdevice
An X25AM subdevice is a logical entity related to an X25AM line. A logical subdevice
can represent a physical object (a terminal or computer), or it can represent some
other software (an application or other process) residing in a computer system. Each
application or physical object communicating over an X25AM line must have a
subdevice defined for it. A subdevice provides a way for an application to communicate
over a switched virtual circuit (SVC) or a permanent virtual circuit (PVC) to another
application.
X25AM subdevices are added to the X25AM line(s), and their characteristics are
defined by using SCF commands to the X25AM subsystem. The maximum number of
subdevices that can be added to a line is determined by the maximum number of
circuits (CIRCUITS modifier) specified for the X25AM I/O process. The maximum
number of circuits allowable depends upon your network subscription.
An X25AM line can be configured for up to 510 circuits (510 subdevices). The number
of configurable subdevices depends on the modifiers PACKETSIZE and L3WINDOW.
For higher packet sizes (more than 256 bytes), the number of subdevices which can be
configured may be less than 510.