The Internet How it works, and its history Compiled and presented by Alex Righolt for the

Topics in this presentation Who owns the internet? Technical background History of the Internet Future of the internet Network models Packet switching Dynamic Name Servers Connecting

Who owns the Internet? -1 One of the greatest things about the Internet is that nobody really owns it. It is a global collection of networks, both big and small.

Who owns the Internet? - 2 These networks connect together in many different ways to form the single entity that we know as the Internet. In fact, the very name comes from this idea of interconnected networks.

Network models - 1 In this centralized model, all communication goes via one central point. If this point fails, the whole system comes to a halt.

Network models - 2 In a decentralized system, costs can be saved by using shorter paths, and some multi- path connections can be made.

Network models - 3 The Internet uses a distributed network. The stations or nodes are scattered all over the world, and are not owned by one organization.

Packet switching - 1 The Internet began to evolve when packet- switching networks came into operation in the 1960s. When transmitted, data is broken up into small packets, sent to its destination and then reassembled.

Packet switching - 2 How it works:

Packet switching - 3

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Packet switching - 7 In this way a single message can be sent to multiple users, via multiple links. Packets can be compressed for speed and encrypted for security.

Dynamic Name Servers - 1 The DNS system forms one of the largest and most active distributed databases on the planet. Without DNS, the Internet would shut down very quickly.

Dynamic Name Servers - 2 All of the machines connected on the internet use names called IP addresses to refer to one another. For example the Habari domain uses an IP address Domain name servers translate domain names to IP addresses, and vice versa.

Dynamic Name Servers - 3 Easy? – No, because: There are billions of IP addresses currently in use, and most machines have a human- readable name as well. There are many billions of DNS requests made every day. Domain names and IP addresses change daily. New domain names get created daily. Millions of people do the work to change and add domain names and IP addresses every day.

Dynamic Name Servers - 4 The Domain Name System is a distributed database, but there are central name servers at the core of the system. The organization Network Solutions was chosen to administer and maintain Internet domain names and IP addresses. This central database is copied to Top Level Domain (TLD) servers around the world.

Connecting - 1 Every computer that is connected to the Internet is part of a network. It may be a single PC in a home connecting to an Internet Service Provider (ISP). POP = Point of Presence

Connecting - 2 At work or at school, you may be part of a local area network (LAN), that connects to the Internet.

Connecting - 4 When you connect to your ISP, you become part of their network. The ISP may then connect to a larger network and become part of their network. NAP = Network Access Points

Connecting - 5 Most large communications companies have their own dedicated backbones connecting various regions.

History – Vision: use computers as communication medium – Distributed networks, packet switching – Four computers connect through ARPA net – First definition of protocols – First use of TCP/IP – Introduction of DNS 1987 – Increased public use of internet – Invention of HTML – Graphically-oriented World Wide Web – Broadband internet.

History Instead of thinking of computers as giant calculators, Licklider laid out a vision in which computers would fulfill their greatest promise as a "communication medium between people. Paul Baran described a distributed telecommunication system that could survive a nuclear strike. This network could still work effectively even if some legs of the network were damaged or removed. It involved a technique called packet switching.

History Four universities in the U.S. set up interface message processors linking computers, in the ARPA net. (Advanced Research Projects Agency) They provided the communications capability required but... It also was to be a unique prototype of future communications systems."

History The first set of protocols were defined: Telnet and FTP functions. Protocols are standards for exchanging data on networks.

History ARPANET started using TCP/IP inter- networking protocols. The way was open for broader public involvement. TCP/IP = Transmission Control Protocol / Internet Protocol

History The T1 backbone of the NSFnet (National Science Foundation), increasingly called the Internet, began to get lots of attention from private enterprises.

History First commercial carriers connected to the Internet: MCI Mail and CompuServe First public dial-up Internet Service Provider: The World Comes On Line

History Tim Berners-Lee invents HTML (Hyper Text Mark-up Language): the idea of linking text in the documents, so there could be cross- references from one research paper to another. Click here to read more.

History – 1992 A tremendous growth in internet use The Mosaic browser introduces the graphically-oriented World Wide Web.

History The first cable modem service in Canada gives households access to broadband internet. This two-way, high-speed connection can be used for interactive applications such as online classrooms, showrooms, or health clinics and many other applications.

The future Already operational: Internet2, a consortium of hundreds of high-speed networks linked by fiber optic backbones. It transmits data at speeds up to 2.4 gigabits per second. Scientists can share specialized equipment like electron microscopes. Internet-enabled devices such as cell phones that send and receive and access the Web.

The future Virtual Collaborative Clinic that connects medical facilities, allowing doctors to manipulate high-resolution, 3-D images of MRI scans and other medical imaging. Doctors can consult and diagnose, and simulate surgery by using a "CyberScalpel."

The future The Internet can bring entire libraries, if not classrooms, into the home for just a few dollars a year. Already on-line universities exist, with more to come accredited institutions which facilitate studies home, using texts and information administered over the Internet.

Finally… Thank you for your interest in this presentation. All information used in this presentation was found on the internet. Send me an if you want a copy of it: