Transcript kjjhghgff

Lesson 7
Networks
Computer Concepts
BASICS 4th Edition
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Objectives
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Describe the benefits and disadvantages of
networks
List and describe the types of networks
List and describe communications hardware
List and describe communications media
Describe the different network topologies
Describe network architecture and protocols
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Computer Concepts BASICS
Vocabulary
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baseband
broadband
bus topology
client/server
network
client
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communications
channel
data communications
Ethernet
local area network
(LAN)
Computer Concepts BASICS
Vocabulary (continued)
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modem
peer-to-peer
network
ring topology
router
server
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star topology
token ring
topology
transmission media
wide area network
(WAN)
Computer Concepts BASICS
Network Building Blocks
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A network is a group of two or more
computers linked together
Data communications is the transmission of
data from one location to another. The five
components of data communications are:
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sending device, signal conversion device,
communication path, receiving device, and
communications software
Computer Concepts BASICS
Network Building Blocks (continued)
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Advantages of a Network:
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Information Sharing, Hardware Sharing, Software
Sharing, and Collaborative environment
Disadvantages of a Network:
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Vulnerable to malicious code, Equipment
problems, Investment in hardware and software,
and Need for maintenance
Computer Concepts BASICS
Network Types
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The two most common types of networks:
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Other types of networks:
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local area networks (LANs)
wide area networks (WANs)
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metropolitan area networks (MANs)
personal area networks (PANs)
home area networks (HANs)
campus area networks (CANs)
Computer Concepts BASICS
Network Types (continued)
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Most local area networks (LANs) connect
personal computers and devices in a limited
geographical area
Each device on the network is called a node
and shares resources such as a printer,
programs, or other hardware
A wireless LAN (WLAN) is similar to a LAN,
but uses no physical wires
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Computer Concepts BASICS
Network Types (continued)
Client/server local area network
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Computer Concepts BASICS
Network Types (continued)
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A wide area network (WAN) covers a large
geographical area. The largest WAN is the Internet.
Most WANs are two or more LANs connected by
routers.
Two variations on a WAN are intranets and
extranets.
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An intranet is designed for the exclusive use of people
within an organization
An extranet allows specified users outside the organization
to access internal information systems
Computer Concepts BASICS
Network Types (continued)
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MANs, PANs, HANs, and CANs:
Metropolitan area network (MAN): Connects users
in a geographic area bigger than a LAN, but smaller
than a WAN
Personal area network (PAN): Connects personal
digital devices within a range of about 30 feet
Home area network (HAN): Contained within a
user’s home
Campus area network (CAN): Collection of LANs
within a limited geographical space, such as a
university campus
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Computer Concepts BASICS
Network Types (continued)
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Network Architectures:
Popular LANs: client/server and peer-to-peer
Client/server network: One or more computers act as
a server. Network operating system software and
software applications are stored on the server. All
other computers on the network are called clients.
Peer-to-peer network: All computers are equals
Internet peer-to-peer: Also called P2P, users connect
directly to each other over the Internet
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Computer Concepts BASICS
Network Hardware
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Communications Devices:
Communications devices facilitate the transmitting
and receiving of data. A list of common
communications devices follows over the next slides:
Dial-up modem: Enables data transmission over
analog telephone lines
DSL and ISDN modems: DSL (digital subscriber line)
and ISDN (integrated services digital network)
modems allow digital transmission over telephone
copper wires
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Computer Concepts BASICS
Network Hardware (continued)
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Communications Devices (continued):
Cable modem: Uses coaxial cable to send and
receive data
Wireless modem: Many mobile devices, such as
a PDA, contain a wireless modem
Network interface card (NIC): Each computer on
a network must have a NIC. Most computers
have a built-in NIC.
Gateway: Software and hardware linking two
different types of networks that use different
protocols
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Computer Concepts BASICS
Network Hardware (continued)
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Communications Devices (continued):
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Router: An intelligent device that directs network
traffic
Wireless access point: Connects wireless
communications devices together to
create a wireless network
Hub: A place of convergence where
data arrives from one or more
directions and is forwarded in
one or more other directions
Wireless Access Point
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Computer Concepts BASICS
Communications Media
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A communications channel is the link that allows data
be transferred from one computer to another
Bandwidth is the transmission capacity of a
communications channel
High bandwidth media, such as cable, fiber, and DSL,
are generally referred to as broadband, whereas a
standard telephone line is referred to as baseband
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Computer Concepts BASICS
Communications Media (continued)
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At one end of the communications channel, you have
a sending device
A communications device, such as a modem,
converts the signal to a form that transmits over a
standard dial-up telephone line or a dedicated line
A switch, located at the telephone, establishes a link
between the sender and receiver
At the receiving end, another modem converts the
signal back into a format that the receiving device can
understand
To send the data through the channel requires some
type of transmission media, physical or wireless
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Computer Concepts BASICS
Lesson 7
Communications Media (continued)
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Physical Media:
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Twisted-pair cable is used in telephone systems. There
are two wires: one carries the signal and the other
absorbs signal interference.
Coaxial cable is used for cable television. The heavily
shielded cable is less prone to interference than
twisted-pair cable.
Fiber-optic cable is made from thin, flexible glass
tubing. They have higher bandwidth than metal wires,
and are less susceptible to interference.
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Communications Media (continued)
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Wireless Media:
Microwave signals are sent in the
form of electromagnetic waves in
straight lines between microwave
stations
Communication satellites are placed
in orbit and maintain a constant
position above one point of the
Earth’s surface
IrDA media (also called infrared
transmission) send signals using
infrared light waves.
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Satellites
Computer Concepts BASICS
Communications Media (continued)
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Wireless Media (continued):
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Bluetooth technology uses radio waves to connect
mobile devices such as cell phones, PDAs, and
notebook computers within 30 feet of each other.
Wi-Fi, or wireless fidelity, identifies any network
based on the 802.11 family of standards governing
wireless transmissions.
WAP is short for Wireless Application Protocol. This
protocol specifies how users access information
instantly through mobile devices such as
smartphones and pagers.
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Network Topologies
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Network configurations are referred to as topologies.
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Within the bus topology, all devices are connected to and
share a master cable called the bus or backbone. There is
no single host computer, and data can be transmitted in
both directions.
With a ring topology the devices are connected in a circle.
Data travels from device to device around the ring.
Star topology: Within a star topology, all devices are
connected to a central hub or computer. All data that
transfers from one computer to another must pass through
the hub.
Computer Concepts BASICS
Communications Protocols
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A protocol is an agreed-upon set of rules and
procedures for transmitting data between two or
more devices. Within networking and LANs, the two
most widely used protocols are:
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The Ethernet protocol which is based on the bus topology,
but can work with the star topology as well
With a token ring all of the computers are arranged in a
circle and a token, a special signal, travels around the ring
On the Internet, the major protocol is TCP/IP which
is the acronym for Transmission Control
Protocol/Internet Protocol
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Computer Concepts BASICS
Network Operating Systems Software
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All computers, including network servers, require an
operating system. Network operating systems
provide features such as administration, file
management, print, communications and security.
Two types of operating systems are necessary in
computer networking:
the desktop operating system, such as Windows or Mac OS
the network operating system
Some desktop operating systems have built-in
networking functions.
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Computer Concepts BASICS
Lesson 7
Summary
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In this lesson, you learned:
 Data communication is the transmission of data from one
location to another.
 A network is a group of two or more computers linked
together.
 The Internet is the biggest network of all.
 Networks have advantages and disadvantages.
 A local area network generally is confined to a limited
geographical area.
 A wide area network is made up of several connected
local area networks.
 The two popular types of LANs are the client/server
network and peer-to-peer network.
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Computer Concepts BASICS
Summary (continued)
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Other types of specialized networks include metropolitan
area networks (MANs), personal area networks (PANs),
home area networks (HANs), and campus area networks
(CANs).
You can use a network for information sharing, hardware
sharing, software sharing, and as a collaborative
environment.
The link through which data is transmitted is the
communications channel.
Transmission media can be either physical or wireless.
Physical media include twisted-pair cable, coaxial cable,
and fiber-optic cable.
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Computer Concepts BASICS
Summary (continued)
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Most networks consist of a network server and computer
clients.
Communications devices facilitate the transmitting and
receiving of data, instructions, and information.
Communications devices include dial-up and cable
modems, DSL and ISDN modems, network interface
cards, gateways, routers, wireless access points, and
hubs.
Network interface cards enable the sending and receiving
of data between the PCs in a network.
A router directs the Internet or network traffic.
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Computer Concepts BASICS
Summary (continued)
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Wireless media includes microwaves, satellites, IrDA,
Bluetooth, and Wi-Fi.
Network topologies include bus, ring, and star.
A protocol is an agreed-upon set of rules and procedures
for transmitting data between two or more devices.
The Ethernet protocol is one of the most popular LAN
protocols.
Token ring is the second most widely used LAN protocol.
TCP/IP is a protocol used by both LANs and WANs to
connect to the Internet.
All computers on a network require an operating system,
and networks require network operating systems.
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Computer Concepts BASICS