User`s guide

ATM Switching

Endtoend ATM

connectivit

5 Networking - ATM

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3EC 17058 AAAA TCZZA Ed. 04

5.1 The ATM Packet Switching Technology

ATM is a connectionoriented packet switching technology using

fixedsize packets, called cells.

These cells consist of a header and a payload and are switched

through a public or private ATM network depending on the

contents of the header.

Endtoend connections are formed by crossconnecting individual

ATM segments in ATM switches.

Each ATM cell carries two labels called Virtual Path Identifier (VPI)

and Virtual Channel Identifier (VCI) as part of its header.

An ATM channel, commonly referred to as Virtual Channel,

is fully identified by these two labels. Therefore, multiple ATM

channels can reside on your DSL line.

All STHome ATM connections are static, i.e. of type Permanent

Virtual Channel (PVC).

The following figure provides an overview of the endtoend

architecture of the ATM connectivity; from your STHome to remote

access devices.

Corporate Access Point

Internet

ISP Access Point

ATM Crossconnect

ADSL Line

Multiple ATM

virtual channels

Ethernet

ATMForum

This channel is not crossconnected

Symbolizes a cross connection.

Hence no endtoend connectivity!

Remote LAN