Chapter 20: Networks and Communications^511
As you might guess, there are different levels and types of networks. Networks are
classified by the size and scope of the area they serve. The most common classifications
for networks are as follows: Local area network (LAN) Usually computers connected to a network that
is confined to a single office or building. The network in an office or a school’s
computer lab is typically a LAN.
Campus area network (CAN) A variation of a LAN that extends to include
computers in buildings that are in close proximity to one another, such as in
an office park or campus setting. The network that connects the buildings of
a college or a manufacturing company’s buildings is an example of a CAN.
Wide area network (WAN) Interconnects LANs and computers that
are located over a large geographical area. Typically, the WAN is built on
dedicated high-speed communications lines. The big WAN is the Internet,
which is actually a network of networks (something called a nexus), but
the network that connects the New York office of a company to its plant
in Washington State is also a WAN.
Metropolitan area network (MAN) A type of WAN that interconnects LANs
and computers within a specific geographical area, such as a city or a cluster
of campuses or office parks. Several cities, including Cleveland, Chicago,
and Spokane, have established MANs to provide connectivity to downtown
businesses.Network Structures
As indicated above, creating a network can be as simple as connecting two PCs together
or connecting together thousands, even millions, or other networks. Depending on the
needs of the users, a network can be quite simple or it can be very complex. There are two
basic network structures: Peer-to-peer (peer-based) networks Two or more computers directly
connected to one another for the sole purpose of directly sharing data and
hardware resources. The very simple network shown in Figure 20-1 shows
a peer-to-peer network. Tom and Sally are directly connected by a cable and
are able to grant permission to each other to open and use files and programs
stored on their PCs and to share CD-ROM drives, printers, and other hardware.
On a peer-based network, each user is responsible for the security and access
of his or her PC because there is no central administrator. A peer-to-peer
network is practically limited to not more than ten PCs arranged as a LAN.
Server-based (client/server) networks A network of connected computers
and peripherals with a centralized server that facilitates the sharing of network
data, software, and hardware resources. A client/server network typically has