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Networks
QUME 185
Introduction to Computer
Applications
Fundamental Concepts
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Network: two or more
computers, or other
devices, connected
together.
Connections: cables,
wireless or other means.
Network communications
follow rules: protocols
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Networks: large and small
LAN, WAN, Internet, Intranet
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LAN – Local Area Network
WAN – Wide Area Network
Internet (public)
Intranet (private)
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Benefits of LANs and WANs
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Increased efficiency and lowered costs
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sharing equipment (printers etc)
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sharing of files and documents (group work)
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sending messages (e-mail, conferencing)
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sharing databases (access to customer lists, price
and inventory information)
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administering shared software
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Client/Server model
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Most networks rely on the client/server
model
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the client is the requesting program or user
(usually a personal computer)
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the server is the computer that:
 manages
network resources
 receives the request from client
 delivers the requested file (or other service) to the
client
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Servers
Servers can have many roles, and often serve
multiple roles. They can be one or any of
the following:
File Server
 Print Server
 Database Server
 Web Server
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The Internet
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The Internet is a group of networks
linked together with routers in a
way that allows any computer on any
network to be able to communicate
with another computer on any other
network.
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The Internet

Corporate LANs and WANs also connect to the
Internet
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Components & Protocols
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Network Components:
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Transmit and receive data
Conform to a common set of rules that enable them to
communicate with each other. These rules are called
protocols
Network Protocols check to see if a connection is
free to send data, and ensure that data do not
collide on the network
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TCP/IP
These two protocols form the basis of
Internet technology
 Powerful and flexible
 Used on the Internet to enable data to be
sent from one computer to another across
multiple networks
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IP – Internet Protocol
Each computer, or other device,
attached to the Internet has an IP
address that uniquely identifies it from
the millions of other computers on the
Internet
 Typical format: 142.25.103.249
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(This is the IP address for viu.ca)
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TCP – Transmission Control Protocol
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Divides large data files into packets
Each packet is transmitted separately
Packets are reassembled at the destination so
that they are understandable as an e-mail
message, Web page or other file type
Process is controlled by TCP
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Transmission process
Data packets are forwarded from one
network gateway to another across the
Internet
 The packets don’t necessarily all take the
same route
 Therefore, may not arrive at their
destination in the same order they were
sent
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Keeping Track of Packets
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Each packet carries:
IP address of sender
 IP address of destination
 Where it belongs in the larger file
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Summary of TCP/IP
Simply stated, TCP/IP allows for the
"handshake" that introduces distant
and different computers to each
other. ... TCP controls and keeps
track of the flow of data packets, IP
addresses and forwards individual
packets. TCP/IP, which became the
required protocol of ARPANET in
1983, also allowed ARPANET to
expand into the Internet,
facilitating features like remote
login via Telnet --- and, later, the
World Wide Web.
FROM: http://web.mit.edu/invent/iow/cerf.html
Vinton Cerf – Developed TCP/IP
http://www.ibiblio.org/pioneers/
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The World Wide Web
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Just one application of the Internet
Web pages are stored on servers
throughout the world
The application software used to access
web pages is called a Browser (such as
Firefox, Safari, Internet Explorer and Opera)
Web browser = Web client
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Some Web Acronyms
HTTP – Hypertext Transfer Protocol
 URL – Uniform Resource Locator – the
unique address of the web page
http://www.viu.ca/index.asp
protocol | domain name | web page
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Corporate Intranets / Extranets
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Organizations use TCP/IP networking protocols
and web technology to create private, corporate
networks
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Intranets – for use within the organization itself: InVIU
for example
Extranets – for use by the organization and, for
example, its suppliers or customers
These networks use the same network
infrastructure (hardware) as the LAN or WAN, but
send the data using internet protocols.
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Networking – just the basics
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Networking is a very complex topic
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This was a very simple overview
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Best to refer to networking
specialists
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Class discussion exercise
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What do you think are the basic
computer skills that a person needs
for 2012 and beyond?
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How a web server works on the Internet