Lecture 1: Facts of network technologies developments (A historical background)

Computer Networks Computer networks? A group of interconnected computers -Represent a logical Result of the evolution of two of the most important scientific and technical branches of modern civilization – Computing and Telecommunications technologies.

From Batch Processing Toward Time-Sharing Queuing Theory 1957 Centralized system based on mainframe Multi-terminal System Time sharing

The Necessity: Time and Resource Sharing “Time sharing tried to make it possible for research institutions to use the processing power of other institutions computers when they had large calculations to do that required more power, or when someone else's facility might do the job better”

Networking History Origins of Internet are hazy, visit www.nethistory.info for interesting reading Vint Cerf: “Internet Father “

Related Definitions and terminologies The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to link several billion devices worldwide.  Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. The Advanced Research Projects Agency Network (ARPANET) is one of the world's first packet switching networks, the first network to implement TCP/IP, and was the main progenitor of what was to become the global Internet. (later DARPA)

Related Definitions and Concepts  ARBA network was initially funded by the Advanced Research Projects Agency (ARPA, later DARPA) within the U.S. Department of Defense for use by its projects at universities and research laboratories in the US. The packet switching of the ARPANET, together with TCP/IP, would form the backbone of how the Internet works.

The ARPANET Growth of the ARPANET (a) December 1969. (b) July 1970. (c) March 1971. (d) April 1972. (e) September 1972.

Related Definitions and Concepts The packet switching was based on concepts and designs by: American engineer Paul Baran,  scientist Donald Davies and Lawrence Roberts of the Lincoln Laboratory. The TCP/IP communication protocols were developed for ARPANET by computer scientists Bob Kahn and Vint Cerf, and also incorporated some designs from Louis Pouzin.

Networking History ARPAnet demonstrated publicly 1961: Kleinrock - queuing theory shows effectiveness of packet-switching 1964: Baran -packet-switching in military applications for survivable networks 1967: ARPAnet conceived by Advanced Research Projects Agency 1969: First ARPAnet node operational Prof. Kleinrock sends a message across from UCLA to Stanford 1972: ARPAnet demonstrated publicly NCP (Network Control Protocol) first host-host protocol First e-mail program ARPAnet has 15 nodes

Networking History... 1970: ALOHAnet satellite network in Hawaii (CSMA developed), later connects to ARPANet 1973: Bob Metcalfe’s PhD thesis proposes Ethernet (CSMA/CD developed) 1974: Cerf and Kahn - architecture for interconnecting networks: the word “Internet” makes its appearance from Cerf’s writings Carrier sense multiple access (CSMA) is a probabilistic media access control (MAC) protocol in which a node verifies the absence of other traffic before 

Networking History... Time sharing became difficult since different machines had different operating systems, versions and programs. However, these led to development of Internet Reference Models Vinton Cerf. Bob Kahn, and (…….) developed TCP/IP Cerf and Kahn’s internetworking principles: simplicity, autonomy - no internal changes required to interconnect networks best effort service model stateless routers decentralized control define today’s Internet architecture

Networking History... 1978: TCP/IP v4 was released Aimed to interconnect different kinds of networks 1979: ARPAnet has 200 nodes 1983: deployment of TCP/IP in ARPAnet 1983: SMTP e-mail protocol defined 1983: DNS defined for name-to-IP-address translation 1985: FTP protocol defined 1988: TCP congestion control 100,000 hosts connected to confederation of networks

Networking History... Early 1990s: WWW Hypertext HTTP: Tim Berners-Lee develops WWW an Internet based hypermedia initiative, and specifies URLs, HTTP and HTML which became basis for today’s WWW 1994: Mosaic (Univ. of Illinois), later Netscape the major browsers until late 1990’s late 1990’s: commercialization of the WWW, with introduction of HTTPS e- commerce is realized Late 1990’s: 50 million computers on Internet 100 million+ users backbone links running at 1 Gbps

Hosts on the Web

Internet Users: By language

Internet Content: By language

Questions Which appeared earlier than the other: WANs or LANs? Why? Reference: http://media.wiley.com/product_data/excerpt/83/EHEP0009/EH EP000983.pdf Summaries this video in Arabic and English https://www.youtube.com/watch?v=9hIQjrMHTv4