Introduction to Tandem X.25 Capabilities

X25AM Connectivity
Tandem X.25 Features and Capabilities
065307 Tandem Computers Incorporated 2–19
Connecting to other Hosts
via PSDNs
To connect a Tandem system to a computer system of other vendor via a PSDN, you
define an X25AM subdevice for the PTP (process-to-process) protocol. Figure 2-9
shows a Tandem system connected to another manufacturer’s computer system over a
PSDN. In this type of configuration, a user application must be written to the X25AM
process. The PTP protocol allows the application programmer to select from a range
of data-exchange modes, which permit the user application to have a greater or lesser
degree of control over the packet exchange.
The user application indirectly controls the contents of the packet, and sends out a
frame to start up the link by issuing Guardian 90 procedure calls.
Note For testing purposes, you can simulate a remote connection by configuring a local DTE as a PTP
subdevice and attaching it to a local Tandem system via a modem. The local DTE can be a PC that is
equipped with an X.25 card (such as the Eicon card), or it can be another host transmitting X.25 packets.
In this type of configuration, the local DTE communicates with the local Tandem system as though the
local DTE were communicating via a PSDN to a Tandem system at a remote site.
Figure 2-9. Connecting to other Host Computer Systems
Another Host System
Tandem
NonStop System
Packet-Switched
Network
PTP
X25AM
Application
X.25 X.25
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