This tutorial is purely historical in nature. Don’t worry if you don’t understand any of the terms used in this tutorial. We will go over them thoroughly later in this course. The sole purpose of this lesson is to acquaint you with the world of networking and the Internet while also introducing you to some of the terminology commonly used in networking.
The Internet is the Web’s backbone, the technical infrastructure that allows it to exist. The Internet, at its most basic, is a large network of computers that communicate with one another.
The History of the Internet
The Internet’s history is somewhat hazy. It began in the 1960s as a research project funded by the United States Army, then evolved into a public infrastructure in the 1980s with the help of many public universities and private companies. The various technologies that support the Internet have evolved over time, but the way it works hasn’t changed much: the Internet is a way to connect computers and ensure that, whatever happens, they remain connected. The history remains connected.
The telephone network was the world’s dominant communication network in the 1960s. The telephone network transmits information from a sender to a receiver using circuit switching, which is an appropriate choice given that voice is transmitted at a constant rate between sender and receiver.
Given the growing importance of computers in the early 1960s, as well as the introduction of timeshared computers, it was perhaps natural to consider how to connect computers so that they could be shared among geographically dispersed users. Such users’ traffic was likely to be bursty—intervals of activity, such as sending a command to a remote computer, followed by periods of inactivity while waiting for a response or contemplating the received response.
Because the users’ traffic was likely to be bursty, there was a growing need for alternatives to circuit switching. Circuit switching was not effective.
Three research groups from around the world began developing packet switching as an efficient and robust alternative to circuit switching, each unaware of the work of the others.
The Need for Packet Switching
Leonard Kleinrock, then a graduate student at MIT, published the first paper on packet-switching techniques. Kleinrock’s work elegantly demonstrated the effectiveness of the packet-switching approach for bursty traffic sources using queuing theory. In 1964, Paul Baran of the Rand Institute began researching the use of packet-switching for secure voice-over military networks, and Donald Davies and Roger Scantlebury of the National Physical Laboratory in England were also working on packet-switching concepts.
The work done at MIT, Rand, and NPL laid the groundwork for today’s Internet. However, the Internet has a long history of a let’s-build-it-and-demonstrate-it attitude dating back to the 1960s. Kleinrock’s MIT colleagues J. C. R. Licklider and Lawrence Roberts went on to lead the computer science program at the United States Advanced Research Projects Agency (ARPA). Roberts published an overall plan for the ARPAnet, the world’s first packet-switched computer network and the direct ancestor of today’s public Internet.
Under Kleinrock’s supervision, the first packet switch was installed at UCLA on Labor Day 1969, and three additional packet switches were installed shortly thereafter at Stanford Research Institute (SRI), UC Santa Barbara, and the University of Utah.
By the end of 1969, the fledgling precursor to the Internet had four nodes. Kleinrock recalls using the network for the first time to perform a remote login from UCLA to SRI, which crashed the system.
By 1972, ARPAnet had grown to about 15 nodes, and Robert Kahn gave its first public demonstration. The network-control protocol (NCP), the first host-to-host protocol between ARPAnet end systems, was completed [RFC 001]. Applications could now be written with the availability of an end-to-end protocol. In 1972, Ray Tomlinson created the first e-mail program. It was the history of ARPAnet.
The ARPA and ARPAnet
By the end of the 1970s, there were about 200 hosts connected to the ARPAnet. By the end of the 1980s, the number of hosts connected to the public Internet, a network confederation similar to today’s Internet, would have reached a hundred thousand. The 1980s would be a period of rapid development.
Much of that expansion was the result of several distinct efforts to create computer networks that linked universities together. BITNET enabled email and file transfers between universities in the Northeast. CSNET (computer science network) was established to connect university researchers who lacked access to ARPAnet. NSFNET was established in 1986 to provide access to NSF-sponsored supercomputing centers. Starting with a 56 kbps backbone, NSFNET’s backbone would reach 1.5 Mbps by the end of the decade and would serve as a primary backbone connecting regional networks.
From history, we know that many of the final pieces of today’s Internet architecture were falling into place in the ARPAnet community. TCP/IP was officially deployed as the new standard host protocol for ARPAnet on January 1, 1983(replacing the NCP protocol).
The transition [RFC 801] from NCP to TCP/IP was a landmark event, with all hosts being required to transfer over to TCP/IP as of that day. TCP was extended significantly in the late 1980s to implement host-based congestion control. The DNS was also created to map between a human-readable Internet name (for example, www.google.com) and its 32-bit IP address [RFC 1034].
The 1990s were heralded by a series of events that represented the Internet’s ongoing evolution and impending commercialization. ARPAnet, the Internet’s forefather, ceased to exist. NSFNET lifted its restrictions on commercial use of the network in 1991. NSFNET would be decommissioned in 1995, with commercial Internet Service Providers carrying Internet backbone traffic.
Expansion of the Internet
The World Wide Web application, which brought the Internet into the homes and businesses of millions of people worldwide, was to be the main event of the 1990s. The Web served as a platform for hundreds of new applications that we now take for granted, such as search (e.g., Google and Bing), Internet commerce (e.g., Amazon and eBay), and social networks (e.g., Facebook).
Tim Berners-Lee invented the Web at CERN between 1989 and 1991, based on ideas originating in earlier work on hypertext by Vannevar Bush in the 1940s and Ted Nelson in the 1960s. Berners-Lee and his colleagues created the first versions of HTML, HTTP, a Web server, and a browser—the four essential Web components. Around the end of 1993, there were approximately 200 Web servers in operation, which was only a foreshadowing of what was to come. This the history.
Around this time, several researchers were developing Web browsers with graphical user interfaces, including Marc Andreessen, who founded Mosaic Communications with Jim Clark, which later became Netscape Communications Corporation. By 1995, university students were regularly surfing the Web with Netscape browsers. Around this time, businesses of all sizes began to run Web servers and conduct business over the Internet. Microsoft began producing browsers in 1996, sparking the browser war between Netscape and Microsoft, which Microsoft eventually won.
Development and Ongoing Evolution of Internet Architecture
The Internet experienced tremendous growth and innovation in the second half of the 1990s, with major corporations and thousands of startups developing Internet products and services. By the turn of the millennium, the Internet supported hundreds of popular applications, including four game changers:
• E-mail, including attachments and Web-accessible e-mail
• The Web, including Web browsing and Internet commerce
• Instant messaging, with contact lists
• Peer-to-peer file sharing of MP3s, pioneered by Napster
Surprisingly, the first two killer apps came from the research community, while the last two were developed by a group of young entrepreneurs.
From 1995 to 2001, the Internet experienced a roller-coaster ride in the financial markets. Hundreds of Internet startups went public and began trading on a stock exchange before they were even profitable. Many companies were valued in the billions of dollars despite the fact that they had no significant revenue streams. In 2000-2001, Internet stocks crashed, and many startups went bankrupt. Nonetheless, a number of companies, including Microsoft, Cisco, Yahoo, e-Bay, Google, and Amazon, emerged as big winners in the Internet space.
Computer networking continues to evolve at a rapid pace. On all fronts, progress is being made, including the deployment of faster routers and higher transmission speeds in both access networks and network backbones.
