Availability Guide for Change Management

Making Communications Subsystem Changes
Online
Availability Guide for Change Management–125506
5-3
Overview of Communications Products
Overview of Communications Products
The communications products provided by Tandem can be organized in the following
categories:
•
The Expand network
•
Device-specific connections
•
SNA network connections
•
OSI network connections (including X.25)
•
Local area network (LAN) connections
•
TCP/IP network connections
Expand
The Expand subsystem is the Tandem network software used to connect NonStop
systems. It extends the operation of the Tandem NonStop Kernel to dispersed nodes.
The Expand subsystem can logically connect as many as 255 geographically distributed
NonStop systems—up to a total of 4,080 processors—into an integrated network.
One important feature of an Expand network is its availability. The Expand subsystem
is designed to support applications requiring 24-hour-a-day, 7-day-a-week, 365-day-a-
year operations. If a communications line fails, communications are rerouted
automatically; there is no need for operator or application intervention.
Device-Specific Connections
Device-specific connections include communications software that permits
communication between Tandem applications and a variety of devices. The devices can
range from workstations to automatic teller machines, factory robots, gasoline pumps,
and hand-held devices.
SNA Network Connections
SNA network connections include products and facilities that allow Tandem systems and
networks to communicate with IBM SNA systems and networks. These interfaces
include batch and interactive SNA device emulation and distributed OLTP. The Tandem
SNAX product family is the group of products that enables Tandem OLTP applications
to be incorporated into an existing SNA network.
OSI Network Connections
Open Systems Interconnection (OSI) network connections include products that
implement the standards of the OSI architecture, including the ITU-T recommendation
for packet-switching networks (X.25). These products enable Tandem networks to
integrate with systems and devices of other vendors providing OSI and X.25
implementations.
Note. If you are already familiar with Tandem’s communications products, you may want to
skip the following information and proceed to “Common Communications Subsystem Changes”
on page 5-4.