X.25 Services; X.25 Characteristics - Intel ER8100STUS - Express 8100 Router Reference Manual

X.25 Services

In this chapter

X.25 Characteristics

Introduction to X.25
Packet Switched Data
Networks (PSDNs)
32
X.25 is available in the Express 8100 Router with X.25
The WAN port must be configured as an X.25 port before it can be used for X.25
services.
As X.25 uses virtual circuits, a number of links (virtual circuits) can be made via
the same X.25 port.
This chapter gives an introduction to X.25 services in the Intel Express 8100
Router.
X.25 is an internationally agreed protocol for communications between a LAN
device (for example a router connected via a modem) and the Packet Switched
Data Network (PSDN) node. The packet switched data network can be either a
Public Data Network (PDN) or a privately owned network. X.25 is independent
of the internal protocols used within the Packet Switched Data Network (PSDN).
X.25 uses the OSI standard reference model, and defines standards for layers 1,
the physical layer; layer 2, the data link layer and layer 3, the network layer.
Packet Switched Data Networks work on a store-and-forward principle; data
packets received at a node in the PSDN are stored until it is convenient for the
network to forward them. This is a cost-effective arrangement as PDNs need not
reserve network bandwidth for packet switched connections; packets can be for-
warded when the bandwidth becomes available. PSDNs can therefore offer com-
petitive rates for data transfer.
Chapter 5