History of the Internet Part 1

1. History of the InternetPart 1 How the environment came to be.

2. 1962 – J.C.R. Licklider • Idea of global network proposed. • He envisioned a globally interconnected set of computers through which everyone could quickly access data and programs from any site. • As head of DARPA (Defense Advanced Research Projects Agency) and by convincing his successors, was able to push forward his ideas.

3. 1961-1964 : Leonard Kleinrock • 1961 published the first paper on packet switching theory. • 1964 Published the first book on the subject. • Before the idea of using packets to communicate, circuit communication was the only way.

4. Packets vs. Circuits • Circuit communication functions by having a set path going from entity A to entity B and back again. • Phones used these type of communication for a long time. • No one else can use any part of the path while its in use. • Sends the whole thing.

5. Packets vs. Circuits • Packet communication functions by breaking up the communication into smaller chunks and letting each of those chunks find their own way. • Doesn’t tie down the entire path while communication is going on. • Issues of how packets can efficiently find their way, assembling them back in the proper order, and lost packets.

6. The First WAN - 1965 • Kleinrock convinced a Lawrence G. Roberts (one of the DARPA guys) of the feasibility of packet communication. • Thomas Merrill and Roberts connected the TX-2 computer in Mass. with the Q-32 computer in Calif. using a telephone line. • Key discovery: Circuit communication bad, packets good.

7. Putting all the Pieces Together • 1966 : Roberts goes to DARPA (sorta like Mr. Smith goes to Washington) to develop the computer network concept further. • 1967 : Publishes plans for the ARPANET. • At a conference discovers two other groups had been working on packet switching as well: NPL and RAND. • Helps to refine his ideas for the ARPANET • 50 kbps line speed proposed

8. Building of the ARPANET -1968 • Frank Heart at Bolt Beranek and Newmann headed a group that was funded to build the hardware (called: Interface Message Processors) required for packet switching to work. • Roberts and others focused on the overall architectural design, network topology, and economics. • A system to measure the network was prepared by Kleinrock’s team at UCLA.

9. A Working Model • 1969 : ARPANET comes into being. • A two node WAN using packet-switching. • One computer was at UCLA, the other at Stanford Research Institute (SRI). • At SRI Doug Engelbart had developed NLS, an early hypertext system. • Key because HTML is basically a hypertext system.

10. A Working Model • SRI supported the Network Information Center led by Elizabeth (Jake) Feinler. • Maintained tables of host name to address mapping. • One month after the computers were connected the first host-to-host message was sent.

11. A Working Model • After UCLA and SRI were successfully connected together two additional nodes were added at UC Santa Barbara and the University of Utah. • Incorporated Visualization projects dealing with the display of 3-D material over the net. • 1969 : 4 Computers on the ARPANET • Work focused on both the network itself and how to utilize the network.

12. Building Applications • 1970 : The Network Working Group under S. Crocker finished the initial ARPANET Host-to-Host protocol, called the Network Control Protocol (NCP). • 1972 : Ray Tomlinson at BBN creates Email, causing a growth in people-to-people communication. • Roberts expanded the basic Email program which functionality such as list, file, forward, and reply.

13. Upgrading the Network Protocol • NCP could not address networks and machines further downstream than a destination IMP (Interface Message Processor) on the ARPANET. • NCP relied on ARPANET to provide end-to-end reliability. • i.e. NCP assumed there would be no errors or lost packets. • Thus, the need for a new version of the NCP protocol for an open-architecture network environment.

14. Upgrading the Network Protocol • 1973 : Kahn and Vint Cerf develop a new protocol which comes to be named Transmission Control Protocol/Internet Protocol (TCP/IP). • Where NCP was more like a device driver, TCP/IP is more like an actual communication’s protocol.

15. The Four Ground Rules • Each distinct network would have to stand on its own and no internal changes could be required to any such network to connect it to the internet. • Communications would be on a best effort basis. • Black boxes (Gateways and Routers) would be used to connect the networks. • No global control at the operations level.

16. Key Problems to Solve • Dealing with packet loss. • Multiple packets enroute. • Proper packet forwarding by gateways and routers. • Error checking for the packets. • Global addressing. • Flow controls. • Interfacing the various operating systems.

17. Initial Solutions • Communication would consist of a very long stream of bytes. • The position of any byte in the stream would be used to identify it. • Flow control would be done by using sliding windows and acknowledgements. • Not expecting the massive growth of LAN’s, the 32 bit IP address scheme was used. • Assumes only 256 individual networks.

18. Side Notes • Packet recover is not always a good thing. • Splitting of TCP and IP. • TCP : No packet left behind. • UDP : Every packet for himself or herself.

19. Taking Form • 1973 : To allow all the different WANs to communicate together TCP/IP and the host naming scheme is developed. The Internet that we know starts to form. • Robert Kahn and Dr. Vinton Cerf • 1980’s : Wide growth of TCP/IP, new applications such as Telnet and FTP are created.

20. (Abbr.) Chronology • 1982 : 235 computers connected to the ARPANET. • 1984 : NSF (National Science Foundation) funded the networking of Universities together using the new technology. • ARPTANET becomes just one of a number of smaller networks connected together. • 1989 : Tim Berners-Lee comes up with initial idea for a hypertext distribution system.

21. (Abbr.) Chronology • 1990 : 300,000 computers on 3,000 separate networks connected together. • 1991 : Berners-Lee develops his idea into pages of information connected together via links, he calls it the World Wide Web. • Pages could be accessed over computer networks using the IP address combined with the name of the page. -> URL (Uniform Resource Locator)

22. (Abbr.) Chronology • 1993 : The prototype of today’s Web Browsers, Mosaic, is developed.