During the Last Lecture

(Computer Networks)

We looked at the role of networks in computing
We looked at several different types of networks
We familiarized ourselves with networking topologies and protocols

Computer Network

Multiple computers that are connected together to share information and other resources
Types of Computer Networks according to the network access policy
Private
Public

Types of Computer Networks

according to the distance between nodes

LAN: Local Area Network
WAN: Wide Area Network

Network Topologies

The pattern in which computers are connected to form a network

Popular patterns:

–Point-to-point
–Star
–Bus
–Ring
Networks are also formed by combining 2 or more of these 4 basic patterns

Networking Protocols

Networks use protocols, or rules, to exchange information through shared channels. These protocols
prevent collisions of data caused by simultaneous transmission between two or more computers. Several
protocols are available for various types of networks. Here we discuss two that are popular for LANs:
Ethernet; Token Ring

Types of Communication Channels

Wire
Wireless
Wireless (Radio) LANs Are Becoming Popular

Today’s Goal:

Introduction to the Internet

To become able to appreciate the role of the Internet in today’s computing
To become familiar with the history and evolution of the Internet

an accident!

•This car was involved in that accident

It belongs to … Mr. Tom Peters of Palo Alto, California
Key benefits:
– Set-up time
– Set-up cost
– Maintenance cost
– Cost
Key challenges:
– Security & privacy
– Quality of service
– Cost

After the accident, Mr. Peters …

filled out a form, giving info about:
Himself
–The circumstances of the accident
–Estimated repair expenses
& then …

1/ 7

• Mr. Peters’s fax machine

2/ 7
ACME Insurance Group’s server in New York

3/ 7

Kim eServices (Pvt) Ltd’s server at Davis Rd, Lahore

4/ 7

Claims processing in Lahore

5/ 7

Kim eServices (Pvt) Ltd’s server at Davis Rd, Lahore

6/ 7

ACME Insurance Group’s server in New York

7/ 7

Mr. Peters’s home PC

Key Question!

Why process the insurance claim in Pakistan?

Answer: Everybody Wins!

Tom Peters
ACME Insurance
Kim eServices

Answer: Everybody Wins!

Tom Peters
ACME Insurance
Kim eServices
Answer: Everybody Wins!
Tom Peters
ACME Insurance
Kim eServices

Answer: Everybody Wins!

Tom Peters
ACME Insurance
Lower premium
&
Quicker turnaround
Better margins due to 50% saving
on claim processing costs

Internal rate of return (IRR)
of 60-80%
Kim eServices
The Key Point …
Kim eServices (Pvt) Ltd is …
… supplying a service
… using local, attractively-priced workers
… to a remote, overseas client
… over the Internet … & making good money in the process!

Internet

Enables users located at far-way locations to easily share information with others located all over the
world
Enables users to easily and inexpensively communicate with others located all over the world
Enables the users to operate and run programs on computers located all over the world
The Internet is unlike any previous human invention. It is a world-wide resource, accessible to all of the
humankind.

Internet Users Worldwide

673M in 2002
1B+ in 2005
(48% wireless)
1.2M Internet users in Pakistan in 5/2000
(1% of population)
In early 2002,
54% of Australian population
51% of Singaporean population
39% of Japanese population
3% of Chinese population

Key Characteristics

Geographic Distribution
Global - reaches around the world
Robust Architecture
Adapts to damage and error
Speed
Data can travels at near ‘c’ on copper, fiber, airwaves

Key Characteristics

Universal Access
Same functionality to everyone
Growth Rate
The fastest growing technology ever
Freedom of Speech
Promotes freedom of speech
The Digital Advantage
Is digital: can correct errors
28.1 Internet: Network of Networks
A large number of networks, interconnected physically
Capable of communicating and sharing data with each other
From the user’s point view, Internet – a collection of interconnected networks – looks like a single,
unified network

28.2 Internet Networking Protocols

Communications on the Internet is controlled by a set of two protocols: TCP and IP
TCP/IP Transmission Control Protocol/Internet Protocol
Networking protocol used by all computers and networks on the Internet
Originally developed by the US DoD for Unix, but now available for most other OSes
TCP breaks down the message to be sent over the Internet into packets

IP routes these packets through the Internet to get them to their destination
When the packets reach the destination computer, TCP reassembles them into the original message

Tools & Services Available on the Internet

Electronic mail (POP, IMAP, SMTP)
Instant messaging (ICQ, MSN)
Remote login (telnet)
File transfer (ftp)
Network news (nntp)
WWW (http)

1960's

1969

- DoD-ARPA creates an experimental network – ARPANET – as a test-bed for emerging
networking technologies
ARPANET originally connected 4 universities & enabled scientists to share info & resources across
long distances
ARPANET continued to expand throughout the 70's and 80's

1970's

Networking tools developed in the 70's include:

1972

- The National Center for Supercomputing Apps. (NCSA) develops the telnet application for
remote login, making it easier to connect to a remote computer

1973

- FTP (File Transfer Protocol) is introduced, standardizing the transfer of files between networked
computers

1980's

1983

- The TCP/IP protocols becomes the only set of protocols used on the ARPANET
This sets a standard for all networks, and generates the use of the term Internet as the net of nets
ARPANET splits into two nets to keep military & non-military network sites separate: ARPANET and
MILNET

1980's

In 1982 and 1983, the first desktop computers begin to appear
Many are equipped with an OS called Berkeley Unix, which includes networking SW, allowing easy
connection to the Internet using telnet
The PC revolution continues through the 80’s, making access to computer resources & net-worked info
increasingly available to public

1985-86:

NSF connects the US’s six supercomputing centers together, calling it the the NSFNET, or
NSFNET backbone
To expand access to the Internet, NSF developed regional nets, which were then connected to the
NSFNET backbone
Plus, NSF supported institutions (universities, etc.) in their efforts to connect to the regional nets

1987

- NSF awards a grant to Merit Network, Inc. to operate & manage future development of the
NSFNET
Merit collaborates with IBM & MCI on R&D for fast networking technologies

1989

- The backbone network is upgraded to T1, making it able to transmit data at speeds of 1.5 Mb/s
(approx. 60 pages of text/second)

1990's1990

- The ARPANET is dissolved

1991

- Gopher is developed at the U of MN
It provides a hierarchical, menu-based method for providing & locating info on the Internet

1993

- CERN releases WWW, developed by Tim Berners-Lee
It uses HTTP and hypertext, revolutionizing the way info is presented & accessed on Internet

1993

- The NSFNET is upgraded to T3 (45 Mb/s or about 1800 pages/s)

1993-1994

- Web browsers Mosaic & Netscape Navigator are introduced
Their GUI makes WWW & Internet more appealing to the general public

1995

- NSFNET is replaced by a new architecture, called vBNS which utilizes regional networks and
Network Access Points