this slides gives beginners the basic knowledge under networking

1. Overview of Computer
Networking

2. Definition of Network
• A network is any collection of independent computers that
communicate with one another over a shared network
medium. A computer network is a collection of two or
more connected computers.
• When these computers are joined in a network, people can
share files and peripherals such as modems, printers,
scanners, tape backup drives, or CD-ROM drives which are
called nodes.
• When networks at multiple locations are connected using
services available from phone companies, people can send
e-mail, share links to the global Internet, or conduct video
conferences in real time with other remote users.

3. Characteristics of a Network
• Every network must have the following features:
– At least two computers- a Server and a Client or
workstation.
– Each computer must have Networking Interface
Card's (NIC)
– A connection medium, usually a wire or cable,
although wireless communication between networked
computers and peripherals is also possible.
– Network/server Operating system software, such as
Windows 2008 Server, Unix, or Linux.

4. Types of Network
• Local Area Network
• Metropolitan Area Network
• Wide Area Network
• Internet
• Intranet and Extranet
• Virtual Private Network
• Cloud Computing

5. Local Area Network (LAN)
• LANs are networks usually confined to a small
geographical area, such as single room
building or a college campus.
• LANs can be small, linking as few as three
computers, but often link hundreds of
computers used by thousands of people.

6. Local Area Network

7. Metropolitan Area Network (MAN)
• This refers to a network within a city. For
example a network covering the city of Accra
or Kumasi.

8. Metropolitan Area Network

9. Wide Area Network
• A Wide Area Network combines multiple LANs that are
geographically separate. It sometimes covers the entire
world and an example is the internet. This is
accomplished by connecting the different LANs using
services such as dedicated leased phone lines, dial-up
phone lines, satellite links, and data packet carrier
services.
• Wide area networking can be as simple as a modem
and remote access server for employees to dial into, or
it can be as complex as hundreds of branch offices
globally linked using special routing protocols and
filters to minimize the expense of sending data sent
over vast distances.

11. The Internet
• The Internet is a system of linked networks
that are worldwide in scope and facilitate data
communication services such as remote login,
file transfer, electronic mail, the World Wide
Web etc. With the meteoric rise.
• The Internet was initially restricted to military
and academic institutions, but now it is a full-
fledged conduit for all forms of information
and commerce.

12. How the Internet Works
• First, you open your Web browser and
connect to a Web site. When you do this, your
computer sends an electronic request over
your Internet connection to your Internet
service provider (ISP). The ISP then routes the
request to a server further up the chain on the
Internet. Eventually, the request will hit
a domain name server (DNS).

13. How Internet works
• The DNS will look for a match for the domain
name you've typed in (such as
www.upsa.edu.gh).
• If it finds a match, it will direct your request
to the proper server's IP address. If it doesn't
find a match, it will send the request further
up the chain to a server that has more
information.

14. How the Internet Works
• The request will eventually come to UPSA Web server.
The server will respond by sending the requested file
in a series of packets. Packets are parts of a file that
range between 1,000 and 1,500 bytes.
• Packets have headers and footers that tell computers
what's in the packet and how the information fits with
other packets to create an entire file.
• Each packet travels back up the network and down to
your computer. Packets don't necessarily all take the
same path -- they'll generally travel the path of least
resistance.

15. How Internet Works
• Due to the fact that packets can travel through multiple
paths to get to their destination, it's possible for
information to route around congested areas on the
Internet. In fact, as long as some connections remain,
entire sections of the Internet could go down and
information could still travel from one section to
another -- though it might take longer than normal.
• When the packets get to you, your device arranges
them according to the rules of the protocols. It's kind
of like putting together a jigsaw puzzle. The end result
is that you see this article.

16. How the Internet Works
• This holds true for other kinds of files as well.
When you send an e-mail, it gets broken into
packets before zooming across the Internet.
• Phone calls over the Internet also convert
conversations into packets using the voice
over Internet protocol (VoIP).

17. Internet Infrastructure

18. Internet Infrastructure

19. Intranet
• An intranet is a private network utilizing Internet-
type tools, but available only within that
organization. For large organizations, an intranet
provides an easy access mode to corporate
information for employees.
• "intra-" is Latin for "within.“ which makes sense
because an intranet works exactly like the
Internet, except it's a network confined within a
company, school, government or organization.

20. Extranet
• Some companies and organizations allow
business partners and clients to access their
intranet sites from remote locations outside of
the company LAN. These extensions of the
intranet are called extranets.
• An Extranet is part of a company‘s intranet that is
accessed by other people or businesses. Usually
this is used in a business-to-business (B2B)
situation, where suppliers or partner/affiliate
companies can share information, forecasts, or
even order products or services

21. Virtual Private Network (VPN)
• VPN uses a technique known as tunneling to
transfer data securely over the Internet to a
remote access server on your workplace
network. Using a VPN helps you save money
by using the public Internet instead of making
long–distance phone dial-up calls to connect
securely with your private network.

22. Tunneling Protocols
• Tunneling enables the encapsulation of a
packet that is sent over the VPN connection
and also encrypts the data. There are two
major types of Tunneling protocols:
– Point-to-Point Tunneling Protocol (PPTP)
– Layer 2 Tunneling Protocol (L2TP)

23. VPN Connection Allowing Remote Access to a Secured
Network

24. VPN Connecting Two Networks

25. Categories of Networks
• Networks can be divided into two main
categories:
– Peer-to-Peer
– Server-Based Architecture

26. Peer-to-Peer
• In its simplest form, a peer-to-peer (P2P) network is
created when two or more PCs are connected and share
resources without going through a separate server. A P2P
network can be an ad hoc connection i.e. a couple of
computers connected via a Universal Serial Bus or cable to
transfer files.
• A P2P network also can be a permanent infrastructure that
links a half-dozen computers in a small office over copper
wires. Or a P2P network can be a network on a much
grander scale in which special protocols and applications
set up direct relationships among users over the Internet
• Example of peer-to-peer is Skype

27. Client-Server
• The term Client/server refers to the concept of
sharing the work involved in processing data
between the client computer and a powerful
computer known as a server.
• The client/server model is basically an
implementation of distributed or cooperative
processing. At the heart of the model is the
concept of splitting application functions
between a client and a server processor.

28. Benefits of Client-Server Architecture
• Databases and management of applications
such as Spreadsheets, Accounting,
Communications and Document
management.
• Network management.
• Centralized file storage

31. Cloud Computing
• It is the practice of using a network of remote
servers hosted on the Internet to store,
manage, and process data, rather than a local
server or a personal computer.
• In the simplest terms, cloud computing means
storing and accessing data and programs over
the Internet instead of your computer's hard
drive. The cloud is just a metaphor for the
Internet.

32. How Cloud Computing Works

33. END OF LECTURE