History of the Internet Part 1

History of the InternetPart 1

How the environment came to be.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

The Four Ground Rules

1. 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.

2. Communications would be on a best effort basis.

3. Black boxes (Gateways and Routers) would be used to connect the networks.

4. No global control at the operations level.

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.

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.

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.

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.

(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.

(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)

(Abbr.) Chronology

• 1993 : The prototype of today’s Web Browsers, Mosaic, is developed.