Information Technology Reference
In-Depth Information
In summary, large star networks and large Ethernet networks
are made from connecting small networks. In star networks, con
nections run between central machines to form larger networks. In
Ethernet networks, individual machines may be connected to hubs
in a hierarchical structure to form segments, and segments are
joined by bridges. Bridges allow segments to function separately and
independently when only local communications are needed, but
bridges provide connections among segments when broader com
munications are needed.
When you hear the term
wireless technology
, your first thoughts
might involve your experiences with telephones. Not many years
ago, wires connected all telephones to a central hub or switch. With
the development of cordless telephones, a base station maintained
the same wired connection to the central hub, but the base station
communicated with your portable cordless handset using radio
waves. When using cordless phones, you can move around the
house, but your conversations are channeled through the same base
station attached to your telephone connection in your home. More
recently, you can use a cell phone that broadcasts your conversation
to a radio tower in your area, but you are no longer required to be
in range of that specific radio tower. Rather, when you move to a
new area, your cell phone communicates with one nearby tower for
awhile, but then may switch its broadcasts to another tower that
may be closer.
This evolution of telephone communications has parallels with
the development of wireless technology for computers. Because
wireless communications extend Ethernet networks, just as cordless
phones and cell phones extend wired telephones, the starting point
is a wirebased Ethernet network. In Ethernet networks:
Messages are divided into relatively short pieces or packets.
Each packet contains a header that includes such information
as the identification of which machine sent the message and
which computer the message is intended for.
Computers are attached logically to a single Ethernet cable.
