Computer Networks & The Internet Lecture 1 Imran Ahmed University of Management & Technology

1. Computer Networks & The Internet Lecture 1 Imran Ahmed University of Management & Technology

2. Goals of the Course • Understand the architecture, operation, and evolution of the Internet • IP, ATM, Optical • Understand the functionality of different network layers. • Get familiar with current Internet research technologies and development efforts. • Understand, how to design a LAN and configuration of it as well. • At the end, students are able to understand well, the technologies which are involved in computer networking now a days.

3. Agenda • Network & its types • What’s the Internet? • What’s a protocol? • History • Network edge • Network core • Access net, physical media • Internet/ISP structure • Performance: loss, delay • Protocol layers, service models

4. Types of Networks • Geographical distance: • Local Area Networks (LAN): Ethernet, Token ring, FDDI • Metropolitan Area Networks (MAN): SMDS (Switched Multi-gigabit Data Service) • Wide Area Networks (WAN): IP, ATM, Frame relay • Information type: • Data networks vs. telecommunication networks • Application type: • Special purpose networks: airline reservation network, banking network, credit card network, telephony • General purpose network: Internet

5. Types of Networks • Right to use: • Private: enterprise networks • Public: telephony network, Internet • Ownership of protocols: • Proprietary: SNA • Open: IP • Technologies: • Terrestrial vs. satellite • Wired vs. wireless • Protocols: • IP, AppleTalk, SNA

6. What is the Internet? • The collection of hosts and routers that are mutually reachable at any given instant • All run the Internet Protocol (IP) • Version 4 (IPv4) is the dominant protocol • Version 6 (IPv6) is the future protocol

7. millions of connected computing devices: hosts = end systems running network apps communication links fiber, copper, radio, satellite transmission rate = bandwidth routers: forward packets (chunks of data) router workstation server mobile local ISP regional ISP company network What’s the Internet: “nuts and bolts” view

8. protocolscontrol sending, receiving of msgs e.g., TCP, IP, HTTP, FTP, PPP Internet: “network of networks” loosely hierarchical public Internet versus private intranet Internet standards RFC: Request for comments IETF: Internet Engineering Task Force What’s the Internet: “nuts and bolts” view router workstation server mobile local ISP regional ISP company network

9. communication infrastructure enables distributed applications: Web, email, games, e-commerce, file sharing communication services provided to apps: Connectionless unreliable connection-oriented reliable What’s the Internet: a service view

10. Human protocols: “What’s the time?” “I have a question” introductions specific msgs sent specific actions taken when msgs received, or other events Network protocols: Machines rather than humans All communication activity in Internet governed by protocols What’s the Protocol? Protocols define format, Order of msgs sent and received among network Entities, and actions Taken on msg Transmission, receipt

11. a human protocol and a computer network protocol: TCP connection response Get http://www.awl.com/kurose-ross Got the time? 2:00 <file> time What’s a protocol? Hi TCP connection req Hi

12. Agenda • Network & its types • What’s the Internet? • What’s a protocol? • History • Network edge • Network core • Access net, physical media • Internet/ISP structure • Performance: loss, delay • Protocol layers, service models

13. 1961: Kleinrock - queueing theory shows effectiveness of packet-switching 1964: Baran – Introduced first Distributed packet-switching Communication networks 1967: ARPAnet conceived and sponsored by Advanced Research Projects Agency – Larry Roberts 1969: first ARPAnet node operational at UCLA. Then Stanford, Utah, and UCSB 1972: ARPAnet demonstrated publicly NCP (Network Control Protocol) first host-host protocol (equivalent to TCP/IP) First e-mail program to operate across networks ARPAnet has 15 nodes and connected 26 hosts Internet History 1961-1972: Early packet-switching principles

14. 1970: ALOHAnet satellite network in Hawaii 1973: Metcalfe’s PhD thesis proposes Ethernet 1974: Cerf and Kahn - architecture for interconnecting networks (TCP) late70’s: proprietary architectures: DECnet, SNA, XNA late 70’s: switching fixed length packets (ATM precursor) 1979: ARPAnet has 200 nodes Cerf and Kahn’s internetworking principles: minimalism, autonomy - no internal changes is required to interconnect networks best effort service model stateless routers decentralized control define today’s Internet architecture Internet History 1972-1980: Internetworking, new and proprietary nets

15. 1983: deployment of TCP/IP 1982: SMTP e-mail protocol defined 1983: DNS defined for name-to-IP-address translation 1985: ftp protocol defined (first version: 1972) 1988: TCP congestion control New national networks: CSnet, BITnet, NSFnet, Minitel 100,000 hosts connected to confederation of networks Internet History 1980-1990: new protocols, a proliferation of networks

16. Early 1990’s:ARPAnet decomissioned 1991:NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995) early 1990s: WWW hypertext [Bush 1945, Nelson 1960’s] HTML, http: Berners-Lee 1994: Mosaic, later Netscape late 1990’s: commercialization of the WWW Late 1990’s: est. 50 million computers on Internet est. 100 million+ users in 160 countries backbone links running at 1 Gbps+ Internet History 1990’s: commercialization, the WWW

17. Growth of the Internet • Number of Hosts on the Internet: Aug. 1981 213 Oct. 1984 1,024 Dec. 1987 28,174 Oct. 1990 313,000 Oct. 1993 2,056,000 Apr. 1995 5,706,000 Jul. 1997 19,540,000 Jul. 2000 93,047,785 Today ~ 250,000,000

18. Recent Growth (1991-2000)

19. 1997 22.5 Million Hosts 50 Million Users 2004 250 Million Hosts 797.9 Million Users [Other estimates range from 850M-950M] Internet - Global Statistics (approx. 2.3 Billion Telephone Terminations, 600 Million PCs and 1.34B mobile phones)

20. Internet Penetration Aug. 2004 • Asia - 255.6 M • No. Amer. -223.8 M • Europe - 222.2 M • Latin Am - 51.2 M • Africa - 12.3 M • Mid-east - 16.8 M • Oceania- 16.0 M --------------------------- • Total - 797.9 M (Source www.internetstats.com)

21. % Internet Use (May 2004) • Sweden (76.8%) • United States (67.6%) • Australia (66.6%) • Netherlands (66.0%) • Hong Kong (63.0%) • Iceland (62.5%) • Denmark (62.5%) • S. Korea (62.0%) • Singapore (60.0%) • Switzerland (59.6%)

22. Languages of Internet Users Source: Global Reach (global-reach.biz/globstats)

23. Who is Who on the Internet ? • Internet Engineering Task Force (IETF):The IETF is the protocol engineering and development arm of the Internet. Subdivided into many working groups, which specify Request For Comments or RFCs. • IRTF (Internet Research Task Force):The Internet Research Task Force is composed of a number of focused, long-term and small Research Groups. • Internet Architecture Board (IAB):The IAB is responsible for defining the overall architecture of the Internet, providing guidance and broad direction to the IETF. • The Internet Engineering Steering Group (IESG):The IESG is responsible for technical management of IETF activities and the Internet standards process. Composed of the Area Directors of the IETF working groups.

24. Internet Standardization Process • All standards of the Internet are published as RFC (Request for Comments). But not all RFCs are Internet Standards ! • available: http://www.ietf.org • A typical (but not only) way of standardization is: • Internet Drafts • RFC • Proposed Standard • Draft Standard (requires 2 working implementation) • Internet Standard (declared by IAB)

25. Services Provided by the Internet • Shared access to computing resources • telnet (1970’s) • Shared access to data/files • FTP, NFS, (1980’s) • Communication medium over which people interact • email (1980’s), on-line chat rooms, instant messaging (1990’s) • audio, video (1990’s) • replacing telephone network? • A medium for information dissemination • USENET (1980’s) • WWW (1990’s) • replacing newspaper, magazine? • audio, video (1990’s) • replacing radio, CD, TV?

26. Today’s Vision • Everything is digital: voice, video, music, pictures, live events, … • Everything is on-line: bank statement, medical record, books, airline schedule, weather, highway traffic, … • Everyone is connected: doctor, teacher, broker, mother, son, friends, enemies

27. What is Next? – many of it already here • Electronic commerce • virtual enterprise • Internet entertainment • interactive sitcom • World as a small village • community organized according to interests • enhanced understanding among diverse groups • Electronic democracy • little people can voice their opinions to the whole world • little people can coordinate their actions • bridge the gap between information haves and have no’s • Electronic Crimes • hacker can bring the whole world to its knee

28. Summary • We have studied about some basic concepts of networks and its types. • Some overview of Internet and protocols. • History of computer networks in the perspective of Internet.