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

1. Centralized system based on mainframe2. Multi-terminal System 3. Time sharing

1957

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”

Early communications systems

I.e. telephone point-to-point links directly connect together the users wishing to

communicate use dedicated communication circuit if distance between users increases beyond the

length of the cable, the connection is formed by a number of sections connected end-to-end in series.

Data Networks

set of interconnected nodes exchange information sharing of the transmission circuits= "switching". many links allow more than one path between every

2 nodes. network must select an appropriate path for each

required connection.

Networking Issues - Telephone

Addressing - identify the end user

phone number 1-201-222-2673 = country code + city code + exchange + number

Routing - How to get from source to destination.

Telephone circuit switching: Based on the phone number.

Information Units - How is information sent

Networking Issues - Internet

Addressing - identify the end user

IP addresses 132.66.48.37, Refer to a host interface = network number + host number

Routing- How to get from source to destination

Packet switching: move packets (chunks) of data among routers from source to destination independently.

Information Units - How is information sent.

packet = data + metadata (header/Addresses).

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.

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.

History 1961-1972: Early packet-switching

principles

1961: Kleinrock - queuing theory shows effectiveness of packet-switching

1964: Baran - packet-switching in military networks1967: ARPAnet – conceived by Advanced Research

Projects Agency1969: first ARPAnet node operational

1972: ARPAnet demonstrated publicly NCP (Network Control Protocol) first host-host

protocol first e-mail program ARPAnet has 15 nodes

History 1972-1980: Internetworking, new and

proprietary nets

1970: ALOHAnet satellite network in Hawaii1973: Metcalfe’s PhD thesis proposes Ethernet1974: Cerf and Kahn - architecture for

interconnecting networkslate70’s: proprietary architectures: DECnet, SNA,

XNAlate 70’s: switching fixed length packets (ATM

precursor)1979: ARPAnet has 200 nodes

Cerf and Kahn’s internetworking principles:

minimalism, autonomy - no internal changes required to interconnect networks

best effort service model stateless routers decentralized control

Defines today’s Internet architecture

History 1980-1990: new protocols,

proliferation of networks

1983: deployment of TCP/IP1982: SMTP e-mail protocol defined 1983: DNS defined for name-to-IP-address

translation1985: FTP protocol defined1988: TCP congestion control

new national networks: CSnet, BITnet, NSFnet, Minitel100,000 hosts connected to confederation of

networks

History 1990 - : commercialization and WWW

early 1990’s: ARPAnet decomissioned1991: NSF lifts restrictions on commercial use of

NSFnet (decommissioned, 1995)early 1990s: WWW

hypertext [Bush 1945, Nelson 1960’s]HTML, http: Berners-Lee1994: Mosaic, later Netscapelate 1990’s: commercialization of WWW

Demand and Supply

Huge growth in users The introduction of the web

Faster home access Better user experience.

Infrastructure Significant portion of telecommunication.

New evolving industries Although, sometimes temporary setbacks

Internet: Users

0100200300400500600700800900

1000

Mil

lion

use

rs

1995 1997 1999 2001 2003 2005

year

Users around the Globe (2005)

Africa

Europe

Latin AmericaAustralia

AsiaPacific

USACanada

MiddleEast

0

50

100

150

200

250

300

350

Africa Asia/Pacific Europe Middle East USA+Canada Latin America Australia

Technology: Modem speed

300 1200 24009600

14400

2880033600

56000

0

10000

20000

30000

40000

50000

60000

70000

1979 1980 1984 1987 1991 1993 1995 1997

year

bp

s

Today’s options Modem: 56 K ISDN: 64K – 128K Frame Relay: 56K ++ Today High Speed Connections

All are available at 5Mb (2005) Cable, ADSL, Satellite.

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/EHEP000983.pdf

Summaries this video in Arabic and English https://www.youtube.com/watch?v=9hIQjrMHTv4