2-1
C

HAPTER

2N

ETWORK

P

LANNING

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 mo st important building
blocks for today’s networking technology.
When performance bottlenecks are c aused 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 between any pair of stations; for Fast
Ethernet, the maximum is two. This is know n 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 by means of a
switch, removes this limitation.
A switch can be easily configured in any Ethe rnet or Fast Ethernet
network to significantly boost bandwidth while using conventional
cabling and network cards.