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As a technology, ATM represents a shar p departur e from LAN
alternatives such as traditional Ethernets th at typically rely on
shared transmission media. That is, with Ethernet, several nodes
often contend for the right to transmit over shared cable segments
that support only one transmission at a time. When a node
successfully captures the media, it transmits its message at the
maximum allowed speed, complet ely consuming the media.
However, even in the best of circumst ances, it is not unusual for tw o
or more nodes to be gin transmitting at the same time a nd interfere
with each others transmission. Ethernet’s design anticipates and
compensates for unpredictable transmission collisions that occur.
How ATM Works
In contrast to other method s, ATM isolates network nodes by fo rc i ng
them to attach to ATM switches using dedicated connections. ATM
switches then interconnect and cooperate wi th each other to form a
network and provide communication connections. While an ATM
node has full use of its switch attachment link, nodes share the
capacity of the links connecting the switches. Unlike Ethernet
networks, this sharing is largely in visible to the nodes. Because of
this and other considerations, ATM provides numerous advantages
and capabilities that are difficult or impossible to obtain with legacy
LAN approaches. Perhaps the most important ATM benefits are its