6
Chapter 1
Internetworking
The term
bridging
was introduced before routers and hubs were imple-
mented, so it's pretty common to hear people referring to bridges as
"switches." That's because bridges and switches basically do the same
thing--break up collision domains on a LAN. But there are differences.
Switches provide this function, but they do it with greatly enhanced manage-
ment ability and features. Plus, most of the time, bridges only had two or
four ports. You could get your hands on a bridge with up to 16 ports, but
that's nothing compared to the hundreds available on some switches!
You would use a bridge in a network to reduce collisions within broadcast
domains and to increase the number of collision domains in your network,
which provides more bandwidth for users.
Figure 1.1 shows how a network would look with all these internetwork
devices in place. Remember that the router will break up broadcast domains
for every LAN interface, but it also breaks up collision domains as well.
F I G U R E 1 . 1
Internetworking devices
Router
Switch
Bridge
Switch: Many collision domains
One broadcast domain
Bridge: Two collision domains
One broadcast domain
Hub: One collision domain
One broadcast domain
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