Computer Hardware / Software
Networks
Computer Hardware / Software
Networks
What is a Computer Network?
A computer network is two (2) or more
computers that are connected to each other
(either by wire or by wireless signal) so that they
can share information
Computer Hardware / Software
Networks
Why create a Computer Network?
To share data
– Files that are created on one computer can be used or
edited on other computers on the network
To share resources
– Hardware resources such as Printers, Scanners, or
even Hard Drives can be configured to be shared over
a Network
To share programs
– With special configurations, you can run programs on
a local computer, but the programs are installed on a
remote computer.
Computer Hardware / Software
Networks
Types of Computer Networks
Local Area Networks (LAN)
Usually involve a small
number of computers
Wide Area Networks (WAN)
Involve lots of computers
The computers are close
together
The computers can be close
together, or can be spread
–This means they can be directly over large distances
connected via wires, or even
wireless
Involves a small amount of
data
–The connection is usually over a
collection of wires
Involves a large amount of
data
Computer Hardware / Software
Networks
Computer Network Setups
CLIENT / SERVER
Peer-to-Peer
Computer Hardware / Software
Networks
Computer Network Set-ups
CLIENT / SERVER
–
–
–
This is where the data and resources of 1
main computer (the SERVER) are shared
with several different other computers (the
CLIENTS)
The SERVER is therefore SERVING its data
and resources to different CLIENTS
This is the most common arrangement of
computer networks
This is also how the largest computer
network in the world is arranged: the
INTERNET
Personal computers connect to several
different server computer systems that share
files, information and programs
Computer Hardware / Software
Networks
Computer Network Set-ups
Peer-to-Peer
–
In a peer-to-peer network, each
computer acts as both a server and a
client.
They offer its own resources, as well as
use the resources of other computers
on the network
–
–
This is the most common network in
very small networks (e.g., homes).
Home computers generally share files
and printers with each other
On a large scale, this type of network
is most common in file sharing (e.g.,
bitTorrent).
Computer Hardware / Software
Networks
Typical Home Networks
Computer Hardware / Software
Networks
Typical Home Computer Network Setups
Modem
Most homes already connect to a phone or cable
television network (or both).
These networks can also be used as part of a computer
network, but require special hardware to make the
connection.
–
–
This is called a modem.
A modem can usually connect directly to a single computer using
a USB cable.
Some modems, with a built-in router, can also connect using a
network cable. Very old modems used to be installed inside the
computer.
Computer Hardware / Software
Networks
Typical Home Computer Network Setups
Modem
Originally modems used sound to connect to the network,
and so it was impossible to use the phone at the same
time
–
Current modems use a series of filters to allow us to use the
telephone and connect to the network at the same time
To hear what it sounded like, check out
http://www.freesound.org/samplesViewSingle.php?id=16475
Computer Hardware / Software
Networks
Typical Home Computer Network Setups
Router
To connect multiple computers to a modem, a router is
required.
–
This is such a common configuration that many high-speed
modems have a built-in router.
The router organizes all of the computers or devices
under its control (i.e., those in the house)
As each computer sends or receives information, the
router directs information
–
from computer to computer, or through the modem.
Computer Hardware / Software
Networks
Typical Home Computer Network Setups
Wired vs Wireless Routers
Most networks are still physically connected using
network cable.
–
This is a wired network and is the easiest to set up. Wired
connections also tend to be faster and more stable.
As portable computing (e.g., laptops, iPods, cell phones)
has become more popular, demand has grown for
wireless network connections.
–
A wireless router uses radio waves to carry information between
computers.
Most wireless routers also have some wired connections
available.
Computer Hardware / Software
Networks
Typical Home Computer Network Setups
Network Interface Card
For a physical (wired) connection to the network, a
computer requires a network interface card (NIC).
The NIC has a plug that accepts a network cable.
–
Older computers required a NIC as an expansion card, but most
newer computers have a NIC built-in to the motherboard.
For a home network with a single computer, a NIC may
not be necessary (e.g. if the modem connects directly to
the computer via a USB connections)
–
Otherwise, a cable from the NIC generally plugs directly into the
router.
Computer Hardware / Software
Networks
Typical Home Computer Network Setups
Wireless Network Adapter
For a wireless connection, the computer requires a
wireless network adapter.
For most desktop systems, this requires an expansion
card.
For more portable computers (e.g., laptops, netbooks,
iPods), the wireless technology is built in to the hardware.
Older wireless hardware often has a fairly large antenna
to carry the signal. Newer hardware has the antenna
hidden inside the hardware case.