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There are so many different types of computer networks in
existence, it can be hard to understand the differences between them,
particularly the ones with very similar-sounding names. This lesson explains
the structures and functions of some of the most popular computer networks.
Types of Networks
There are several different types of computer networks.
Computer networks can be characterized by their size as well as their purpose.
The size of a network can be expressed by the geographic
area they occupy and the number of computers that are part of the network.
Networks can cover anything from a handful of devices within a single room to
millions of devices spread across the entire globe.
Some of the different networks based on size are:
Personal area network, or PAN
Local area network, or LAN
Metropolitan area network, or MAN
Wide area network, or WAN
In terms of purpose, many networks can be considered general
purpose, which means they are used for everything from sending files to a
printer to accessing the Internet. Some types of networks, however, serve a
very particular purpose. Some of the different networks based on their main
purpose are:
Storage area network, or SAN
Enterprise private network, or EPN
Virtual private network, or VPN
Let's look at each of these in a bit more detail.
Personal Area Network
A personal area network, or PAN, is a computer network
organized around an individual person within a single building. This could be
inside a small office or residence. A typical PAN would include one or more
computers, telephones, peripheral devices, video game consoles and other
personal entertainment devices.
If multiple individuals use the same network within a
residence, the network is sometimes referred to as a home area network, or HAN.
In a very typical setup, a residence will have a single wired Internet
connection connected to a modem. This modem then provides both wired and
wireless connections for multiple devices. The network is typically managed
from a single computer but can be accessed from any device.
This type of network provides great flexibility. For
example, it allows you to:
Send a document to the printer in the office upstairs while
you are sitting on the couch with your laptop.
Upload the photo from your cell phone to your desktop
computer.
Watch movies from an online streaming service to your TV.
If this sounds familiar to you, you likely have a PAN in
your house without having called it by its name.
Local Area Network
A local area network, or LAN, consists of a computer network
at a single site, typically an individual office building. A LAN is very useful
for sharing resources, such as data storage and printers. LANs can be built
with relatively inexpensive hardware, such as hubs, network adapters and
Ethernet cables.
The smallest LAN may only use two computers, while larger
LANs can accommodate thousands of computers. A LAN typically relies mostly on
wired connections for increased speed and security, but wireless connections
can also be part of a LAN. High speed and relatively low cost are the defining
characteristics of LANs.
LANs are typically used for single sites where people need
to share resources among themselves but not with the rest of the outside world.
Think of an office building where everybody should be able to access files on a
central server or be able to print a document to one or more central printers. Those
tasks should be easy for everybody working in the same office, but you would
not want somebody just walking outside to be able to send a document to the
printer from their cell phone! If a local area network, or LAN, is entirely
wireless, it is referred to as a wireless local area network, or WLAN.
Metropolitan Area Network
A metropolitan area network, or MAN, consists of a computer
network across an entire city, college campus or small region. A MAN is larger
than a LAN, which is typically limited to a single building or site. Depending
on the configuration, this type of network can cover an area from several miles
to tens of miles. A MAN is often used to connect several LANs together to form
a bigger network. When this type of network is specifically designed for a
college campus, it is sometimes referred to as a campus area network, or CAN.
Wide Area Network
A wide area network, or WAN, occupies a very large area,
such as an entire country or the entire world. A WAN can contain multiple
smaller networks, such as LANs or MANs. The Internet is the best-known example
of a public WAN.
Private Networks
One of the benefits of networks like PAN and LAN is that
they can be kept entirely private by restricting some communications to the
connections within the network. This means that those communications never go
over the Internet.
For example, using a LAN, an employee is able to establish a
fast and secure connection to a company database without encryption since none
of the communications between the employee's computer and the database on the
server leave the LAN. But what happens if the same employee wants to use the
database from a remote location? What you need is a private network.
One approach to a private network is to build an enterprise
private network, or "EPN. An EPN is a computer network that is entirely
controlled by one organization, and it is used to connect multiple locations.
Historically, telecommunications companies, like AT&T, operated their own
network, separate from the public Internet. EPNs are still fairly common in
certain sectors where security is of the highest concern. For example, a number
of health facilities may establish their own network between multiple sites to
have full control over the confidentiality of patient records.
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