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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