25 Over Isdn Submenu - Funkwerk bintec R4100 User Manual

8
X.25 over ISDN Submenu
8 X.25 over ISDN Submenu
X.25 The TCP/IP protocol family penetrates applications being classically in the do-
main of the X.25 protocol family.
For example, Point-of-Sales (POS) applications have historically been set up
with X.25. The terminals were using an asynchronous, serial protocol to transfer
standardized POS messages to the POS server. The terminals where connect-
ed to an X.25 PAD with a RS232 (V.24) connection. The X.25 PAD established
X.25 calls via a generic X.25 network to a server connected directly to X.25.
Today, there are only few generic X.25 networks in use. Most servers still speak
X.25, but today most terminals are connected to the Public Switched Telephone
Network (PSDN) by either analogue (POTS) or digital (ISDN) connections.
bintec gateways are able to route X.25 calls between the PSTN and other X.25
carrying networks (i.e. X.21, Ethernet, TCP, ...). They are often used as dialin-
node for example for POS purposes. All ISDN capable bintec gateways can
work with digital connected terminals. Analogously connected terminals can
serve bintec gateways with built-in digital modems.
bintec gateways may not only route X.25 calls. They are also capable to termi-
nate X.25 calls and convert them to TCP. This can be achieved by using the fea-
ture "X.25 to TCP conversion" (see "X.25 to TCP conversion Submenu" on
page 47).
This document provides for information about the "X.25 over ISDN" feature of
bintec gateways.
Principles ISDN, or more generally speaking of PSTN, can be seen as an X.25 carrying
physical network (layer 1 of the OSI model). Physical networks are set up as so-
called "interfaces" within bintec gateways. Interfaces can be hardware-oriented
or virtual. The X.25 switch routes X.25 calls between different interfaces.
Hardware oriented interfaces correspond to real hardware units. The Ethernet
interfaces of the bintec router corresponds exactly to the physical plug repre-
senting the Ethernet connection. If there are multiple Ethernet plugs, there are
also multiple Ethernet interfaces. Ethernet is a typical example of a hardware-
oriented interface.
X.25 bintec User's Guide 61