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286 Part Two Information Technology Infrastructure

TYPES OF NETWORKS

There are many different kinds of networks and ways of classifying them. One
way of looking at networks is in terms of their geographic scope (see Table 7.1).

Local Area Networks
If you work in a business that uses networking, you are probably connecting to
other employees and groups via a local area network. A local area network
(LAN) is designed to connect personal computers and other digital devices
within a half-mile or 500-meter radius. LANs typically connect a few comput-
ers in a small office, all the computers in one building, or all the computers in
several buildings in close proximity. LANs also are used to link to long-distance
wide area networks (WANs, described later in this section) and other networks
around the world using the Internet.
Review Figure 7.1, which could serve as a model for a small LAN that
might be used in an office. One computer is a dedicated network file server,
providing users with access to shared computing resources in the network,
including software programs and data files.
The server determines who gets access to what and in which sequence.
The router connects the LAN to other networks, which could be the Internet
or another corporate network, so that the LAN can exchange information
with networks external to it. The most common LAN operating systems
are Windows, Linux, and Novell. Each of these network operating systems
supports TCP/IP as their default networking protocol.
Ethernet is the dominant LAN standard at the physical network level,
specifying the physical medium to carry signals between computers, access
control rules, and a standardized set of bits used to carry data over the system.
Originally, Ethernet supported a data transfer rate of 10 megabits per second
(Mbps). Newer versions, such as Gigabit Ethernet, support a data transfer
rate of 1 gigabit per second (Gbps), respectively, and are used in network
backbones.
The LAN illustrated in Figure 7.1 uses a client/server architecture where
the network operating system resides primarily on a single file server, and
the server provides much of the control and resources for the network.
Alternatively, LANs may use a peer-to-peer architecture. A peer-to-peer
network treats all processors equally and is used primarily in small networks
with 10 or fewer users. The various computers on the network can exchange
data by direct access and can share peripheral devices without going through
a separate server.
In LANs using the Windows Server family of operating systems, the peer-to-
peer architecture is called the workgroup network model, in which a small group
of computers can share resources, such as files, folders, and printers, over the

TABLE 7.1 TYPES OF NETWORKS

TYPE AREA
Local area network (LAN) Up to 500 meters (half a mile); an office or floor of a building
Campus area network (CAN) Up to 1,000 meters (a mile); a college campus or corporate facility
Metropolitan area network (MAN) A city or metropolitan area
Wide area network (WAN) A transcontinental or global area

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