Chapter 5:
Computer Networks
What Is a Network?
*Network: A connected system of objects or people
*Computer network: A collection of computers and
other hardware devices connected together so
that users can share hardware, software, and
data, as well as electronically communicate with
each other
*Internet: Largest computer network in the world
*Examples of networks
-Business networks
-Phone networks
Networking and
Communications Applications
1- Mobile phones (wireless phones)
*Cellular (cell) phones
- Must be within range of cell tower to function
*Satellite phones
- Used where cell service isn’t available
Networking and
Communications Applications
Networking and
Communications Applications
Global positioning system (GPS): Uses satellites
to determine the exact geographic location of
the receiver
-Commonly found in cars today
-Available as handheld units
-Used by the military, travelers,
and others who need to know their
precise location
Network Topologies
Topology: How the devices in the network (called
nodes) are arranged
1-Star networks: All devices connect to a central device
or hub)
2-Bus networks: All devices connect to a central cable
3-Ring networks: Devices connect to one another in a
ring
4-Mesh networks: Multiple connections between
devices
Some networks use a combination of topologies
Network Topologies
Types of Networks
1-Local area network (LAN): Small geographical
area (office, campus, etc.)
2-Wide area network (WAN): Large
geographical area (Internet)
3-Intranet: Private network set up by an
organization for use by its employees
4-Extranet: Intranet that is at least partially
accessible to authorized outsiders
Data Transmission Characteristics
*Transmission directions
-Simplex transmission (one way only)
-Half-duplex transmission (one way at a time)
-Full-duplex transmission (both ways at the same
time)
Wireless Network Transmission
Media
*Use radio signals
- Short-range (such as Bluetooth)
wireless keyboard
- Medium-range (such as Wi-Fi)
wireless LANs ,portable PC users to the Internet .
-Longer-range (Wi-MAX)
wide geographic areas
Communications Protocols
*Communications protocol: An agreed-upon
standard for transmitting data between two
devices on a network
TCP/IP and Wireless Application
Protocol (WAP)
*TCP/IP (Transmission Control
Protocol/Internet Protocol): Used for
transferring data over the Internet
-Uses packet switching
*Wireless Application Protocol (WAP):
A standard for delivering Internet
content to mobile devices
Networking Hardware
1-Modem: Device that connects a computer to
the Internet or to another computer
Networking Hardware for Connecting
Devices and Networks
* Hub: Central device that connects all of the
devices on the network
* Gateway: A devices that connects two
different networks
- Bridge: Usually connects wired LANs
- Router : Can be wired or wireless
Other Networking Hardware
*Repeater: Amplifies signals along a network
*Antenna: Used when Wi-Fi networks need to
go further than hardware normally allows
Networking Hardware
Summary
*What Is a Network?
*Networking and Communications Applications
*Types of Networks
*How Does Data Travel Over a Network?
*Networking Standards and Communications
Protocols
*Networking Hardware