Computer basics

1. Computer Basics
Lecture 8: Network and Internet
Dr. Mohamed Medhat Dr. Abdelrahman Morsi
m.abdelraheem @aun.edu.eg abdelrahman.morsi@aun.edu.eg
Electrical Engineering Department
Faculty of Engineering
Assiut University
10th Week, 1st Semester 2023 - 2024
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2. Contents:
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1. The Network
2. LANs, MANs, and WANs
3. Network Architectures
4. Network Topologies
5. The Intranet
6. Communication Devices
7. The Internet
8. Connecting to the Internet
9. Access Providers
10. Internet Addresses

3. • Network is a collection of computers and devices connected together via
communications devices and transmission media
• Many businesses network their computers together to facilitate communications, share
hardware, share data and information, share software
• A network can be internal to an organization or span the world by connecting to the
Internet
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The Network

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The Network (Cont.)

5. • Advantages of using network:
1. Facilitating communications
• Using a network, people communicate efficiently and easily via e-mail, …, etc
2. Sharing hardware
• In a networked environment, each computer on the network can have access to hardware on the
network (e.g., shared printer)
3. Sharing data and information
• In a networked environment, any authorized computer user can access data and information stored
on other computers on the network.
• Example: a large company might have a database of customer information
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The Network (Cont.)

6. • Networks can be classified according
to their area coverage to:
1. LAN
2. MAN
3. WAN
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LANs, MANs, and WANs

7. • Local Area Network (LAN):
• It is a network that connects
computers and devices in a limited
geographical area
• Examples: home, school computer
laboratory, office building, …, etc.
• Each computer or device on the
network, called a node
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LANs, MANs, and WANs: Local Area Network

8. • Wireless LAN (WLAN):
• It is a LAN that uses no physical wires
• Computers and devices that access WLAN
must have built-in wireless capability or the
appropriate wireless network card or USB
network adapter
• Very often, a WLAN communicates with a
wired LAN for access to its resources, such as
software, hardware, and the Internet
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LANs, MANs, and WANs: Local Area Network (Cont.)

9. • Metropolitan Area Network (MAN):
• It is a high-speed network that connects local
area networks in a metropolitan area such as
city or town
• A MAN typically includes one or more LANs,
but covers a smaller geographic area than a
WAN
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LANs, MANs, and WANs: Metropolitan Area Network

10. • Wide Area Network (WAN):
• It is a network that covers a large geographic
area (such as a city, country, or the world)
• It uses a communications channel that
combines many types of media such as
telephone lines, cables, and radio waves
• A WAN can be one large network or can
consist of two or more LANs connected
together
• The Internet is the world’s largest WAN
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LANs, MANs, and WANs: Wide Area Network

11. • The design of computers, devices, and
media in a network, sometimes called
the network architecture
• Network architecture is categorized as:
1. Client/Server Network
2. Peer-to-Peer Network
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Network Architecture
Client/Server Peer-to-Peer

12. • On a client/server network, one or more computers act as
a server, and the other computers on the network request
services from the server
• A server, sometimes called a host computer, controls
access to the hardware, software, and other resources on
the network and provides a centralized storage area for
programs, data, and information
• The clients are other computers and mobile devices on the
network that rely on the server for its resources
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Network Architecture: Client/Server Network

13. • Some servers, called dedicated servers, perform a specific
task
• Examples:
• File server: stores and manages files
• Print server: manages printers and documents being printed
• Database server: stores and provides access to a database
• Web server: delivers requested web pages to your computer
• Client/server model is efficient in a network of 10 nodes
(computers) or more
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Network Architecture: Client/Server Network (Cont.)

14. • One type of peer-to-peer network is a simple, inexpensive
network that typically connects fewer than 10 computers
• Each computer, called a peer, has equal responsibilities
and capabilities, sharing hardware (such as a printer), data,
or information with other computers on the peer-to-peer
network
• Each computer stores files on its own storage devices
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Network Architecture: Peer-to-Peer Network

15. • Internet peer-to-peer is another type of peer-to-peer,
called P2P, describes an Internet network on which
users access each other’s hard disks and exchange files
directly over the internet
• This type of peer-to peer network sometimes is called
a file sharing network because users with compatible
software and an internet connection copy files from
someone else’s hard disk to their hard disks
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Network Architecture: Peer-to-Peer Network (Cont.)

16. • A network topology refers to the layout of the
computers and devices in a communications
network
• Three commonly used network topologies are:
1. Star
2. Bus
3. Ring
• Most networks, including the internet, use
combinations of these topologies
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Network Topologies

17. • On a star network, all of the computers and
devices (nodes) on the network connect to a
central device, thus forming a star
• Two types of devices that provide a common
central connection point for nodes on the
network are a hub and a switch
• All data that transfers from one node to other
passes through the hub or switch
• Star networks are fairly easy to install and
maintain
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Network Topologies: Star Network

18. • On a star network, if one node fails, only that
node is affected
• The other nodes continue to operate normally
• If the hub or switch fails, the entire network is
inoperable until the device is repaired
• Most large star networks, therefore, keep backup
hubs or switches available in case the primary
one fails
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Network Topologies: Star Network (Cont.)

19. • A bus network consists of a single central cable,
to which all computers and other devices
connect
• The bus is the physical cable that connects the
computers and other devices
• The bus in a bus network transmits data,
instructions, and information in both directions
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Network Topologies: Bus Network

20. • When a sending device transmits data, the
address of the receiving device is included with
the transmission so that the data is routed to the
appropriate receiving device
• On a bus network, the failure of one device
usually does not affect the rest of the bus
network
• However, the failure of the bus stops the entire
network
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Network Topologies: Bus Network (Cont.)

21. • On a ring network, a cable forms a closed loop (ring)
with all computers and devices arranged along the ring
• Data transmitted on a ring network travels from device
to device around the entire ring, in one direction
• When a computer or device sends data, the data
travels to each computer on the ring until it reaches its
destination
• If a computer or device on a ring network fails, the
entire network potentially could stop functioning
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Network Topologies: Ring Network

22. • An intranet (intra means within) is an internal network
that uses internet technologies
• Intranets generally make company information
accessible to employees and facilitate working in
groups
• An intranet essentially is a small version of the internet
that exists within an organization
• An intranet typically includes a connection to the
internet
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The Intranet

23. • A communications device is any type of hardware capable of transmitting data,
instructions, and information between a sending device and a receiving device
• At the sending end, a communications device sends the data, instructions, or
information from the sending device to a communications channel
• At the receiving end, a communications device receives the signals from the
communications channel
• Examples: dial-up modems, digital modems, network cards, wireless access points,
routers, and switches
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Communication Devices

24. • A dial-up modem is a communications device that can convert
digital signals to analog signals and analog signals to digital
signals, so that data can travel along an analog telephone line
• Remember: an analog signal consists of a continuous electrical
wave, and a digital signal consists of individual electrical pulses
that represent bits grouped together into bytes
• A dial-up modem connected to a sending computer converts the
computer’s digital signals into analog signals
• The analog signals then can travel over a standard telephone line
• The standard data transfer rate of dial-up modem is 56 Kbps
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Communication Devices: Dial-Up Modems

25. • A digital modem is a communications device that
sends and receives data and information to and from
a digital line
• Example of digital modem is the DSL modem
• DSL modem includes built-in Wi-Fi connection
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Communication Devices: Digital Modems

26. • A network card, sometimes called a network
interface card (NIC), is a communication device
that enables a computer to access a network
• Examples:
• Ethernet card
• Wifi card
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Communication Devices: Network Cards

27. • A wireless access point is a central communications
device that allows computers and devices to transfer
data wirelessly among themselves or to transfer data
wirelessly to a wired network
• Wireless access points have high-quality antennas for
optimal signals
• For the best signal, some manufacturers suggest
positioning the wireless access point at the highest
possible location, such as room ceil
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Communication Devices: Wireless Access Points

28. • A router is a communications device that connects
multiple computers or other routers together and
transmits data to its correct destination on a network
• On the largest scale, routers along the internet
backbone forward data packets to their destination
using the fastest available path
• For smaller business and home networks, a router
allows multiple computers to share a single high-
speed internet connection
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Communication Devices: Routers

29. • A switch is a device that provides a central point for cables in a network
• Switches can access more than one network in the same LAN
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Communication Devices: Switches

30. • One of the major reasons business, home, and other users purchase computers is for
internet access
• The internet, also called the Net, is a worldwide collection of networks that links millions
of businesses, government agencies, educational institutions, and individuals
• The World Wide Web, or simply the Web, and e-mail are two of the more widely used
internet services
• Other services include chat rooms, instant messaging, and VoIP (Voice over Internet
Protocol)
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The Internet

31. • The internet has its roots in a networking project started
by the Pentagon’s Advanced Research Projects Agency
(ARPA), an agency of the U.S. Department of Defense
• ARPA’s goal was to build a network that
1. allowed scientists at different physical locations to share
information and work together on military and scientific
projects
2. could function even if part of the network were disabled
or destroyed by a disaster such as a nuclear attack
• That network, called ARPANET, became functional in
September 1969, linking scientific and academic
researchers across the United States
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The Internet: History of the Internet

32. • Many home and small business users connect to the internet via high-speed
broadband internet service
• With broadband internet service, your computer or mobile device usually is connected
to the internet the entire time it is powered on
• Examples of broadband internet service: cable, DSL, fiber, radio signals, and satellite
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Connecting to the Internet

33. • Cable internet service:
• It provides high-speed internet
access through the cable television
network via a cable modem
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Connecting to the Internet (Cont.)
• DSL (Digital Subscriber Line):
• It provides high-speed internet
connections using regular copper
telephone lines

34. • Fiber to the Premises (FTTP):
• It uses fiber-optic cable to provide
high-speed internet access to home
and business users
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Connecting to the Internet (Cont.)
• Cellular radio network:
• It offers high-speed internet
connections to devices with built-in
compatible technology or computers
with wireless modems

35. • Satellite internet service:
• It provides high-speed internet connections
via satellite to a satellite dish that
communicates with a satellite modem
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Connecting to the Internet (Cont.)

36. • An access provider is a business that provides
individuals and organizations access to the internet
free or for a fee
• An ISP (Internet service provider) is a regional or
national access provider
• A regional ISP usually provides Internet access to a
specific geographic area
• A national ISP is a business that provides internet
access in cities and towns nationwide
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Access Providers

37. • The Internet relies on an addressing system much like the postal service to send data and
information to a computer at a specific destination
• An IP address, short for Internet Protocol address, is a number that uniquely identifies
each computer or device connected to the Internet
• The IP address usually consists of four groups of numbers, each separated by a dot
• The number in each group is between 0 and 255
• Example: 72.14.207.99
• In general, the first portion of each IP address identifies the network and the last portion
identifies the specific computer
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Internet Addresses