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Chapter 2: Network Planning

Introduction to Switching

A network switch allows simultaneous transmission of multiple packets via
non-crossbar switching. This means that it can partition a network more efficiently
than bridges or routers. The switch has, therefore, been recognized as one of the
most important building blocks for today’s networking technology.
When performance bottlenecks are caused by congestion at the network access
point (such as the network card for a high-volume file server), the device
experiencing congestion (server, power user, or hub) can be attached directly to a
switched port. And, by using full-duplex mode, the bandwidth of the dedicated
segment can be doubled to maximize throughput.
When networks are based on repeater (hub) technology, the maximum distance
between end stations is limited. For Ethernet, there may be up to four hubs betw een
any pair of stations; for Fast Ethernet, the maximum is two; and for Gigabit Ethernet
the maximum is one. This is known as the hop count. However, a switch turns the
hop count back to zero. So subdividing the network into smaller and more
manageable segments, and linking them to the larger network b y means of a switch,
removes this limitation.
A switch can be easily configured in any network to significantly boost bandwidth
while using conventional cabling and network cards.