Path Builder S700 Module And Application Overview; Atm Overview; Virtual Circuits - 3Com 3C63400-3AC-C - PathBuilder S700 Switch Reference Manual

4

ATM Overview

Virtual Circuits

P B
ATH UILDER
A
PPLICATION
This chapter provides a brief overview of ATM (Asynchronous Transfer Mode)
technology, describes the features and operation of each of the PathBuilder S700
WAN access switch (PathBuilder S700) modules, and discusses applications
supported by the PathBuilder S700. It contains the following sections:
ATM Overview
n
System Module Overview
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ATM Module Overview
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Application Module Overview
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Supported Applications
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For specifications for the PathBuilder S700 modules, see "Specifications" in
Chapter 1.
ATM provides the means of simultaneously transferring a wide variety of services
with different protocols and bandwidth requirements such as voice, packet data,
and video between end users or user networks. It does so by segmenting the input
data streams into 53-byte cells, assigning the cells to virtual circuits set up in the
ATM network, multiplexing the cells for transmission according to the bandwidth
requirements of the individual data streams, and reassembling the cells into the
original data streams at the receiving end.
For more detail about how to apply the PathBuilder S700 to provide ATM WAN
access, see "Supported Applications" in Chapter 4.
ATM networks are organized into virtual circuits or logical duplex paths between
two ATM unit ports.
Each transmission direction in a virtual circuit is referred to as a virtual channel.
Virtual channels are then grouped into virtual paths between two ports. The
channels and paths are assigned numbers: VPIs (Virtual Path Indicators) and VCIs
(Virtual Channel Indicators). Figure 46 illustrates this scheme.
S700 M
ODULE AND
O
VERVIEW