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COSC6377: Computer Networks

COSC6377: Computer Networks. Computer Networking: A Top Down Approach Featuring the Internet , 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2004. Rong Zheng rzheng@cs.uh.edu. Introduction. Overview of the course Basic concepts and structures in computer networking

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COSC6377: Computer Networks

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  1. COSC6377: Computer Networks Computer Networking: A Top Down Approach Featuring the Internet, 3rd edition. Jim Kurose, Keith RossAddison-Wesley, July 2004. Rong Zheng rzheng@cs.uh.edu Introduction

  2. Introduction • Overview of the course • Basic concepts and structures in computer networking • Network architecture Introduction

  3. Computer Networks • A computer network is a system for communication among two or more computers • What amounts to “computers”? • What kind of communication? – “digital” • System: both software & hardware • Examples? Our focus is on the Internet Introduction

  4. History of the Internet • 61-72: development of packet switching • 72-80: Proprietary networks and internetworking • Multiple packet switching networks • “Networks of networks”: earlier development of TCP, UDP, IP • ALOHA, Ethernet • 80-90: proliferation of networks • Standardization of networking protocols TCP/IP, DNS etc • NSF builds NSFNET as backbone, links 6 Supercomputer centers, 1.5 Mbps, 10,000 computers • 90’s: Internet explosion • 94: NSF backbone dismantled, multiple private backbones • Emergence of World Wide Web (invented by Time Berners-Lee) Introduction

  5. Internet “Hall of Fame” • Al Gore, former vice president of USA • Vinton G. Cerf and Robert E. Kahn • 2004 Turing Award winner “For pioneering work on internetworking, including the design and implementation of the Internet's basic communications protocols, TCP/IP, and for inspired leadership in networking” • Turing lecture: http://www.acm.org/sigs/sigcomm/sigcomm2005/webcast.html • David Clark et al “end2end arguments” • Van Jacobson, TCP congestion control • Robert Metcalfe, inventor of Ethernet • … Introduction

  6. 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 Jan. 1997 16,146,000 Jan. 1999 56,218,000 Jan. 2001 109,374,000 Jan 2003 171,638,297 Data available at: http://www.isc.org/ Introduction

  7. Growth of the Internet • Traffic on Internet (in TB/mo) 1990 1.0 1991 2.0 1992 4.4 1993 8.3 1994 16.3 1996 1,500 1997 2,500 - 4,000 1998 5,000 - 8,000 1999 10,000 - 16,000 2000 20,000 - 35,000 2001 40,000 - 70,000 2002 80,000 - 140,000 Andrew Odlyzko, “Internet traffic growth: Sources and implications” Introduction

  8. Growth of the Internet • Internet bandwidth • Nielsen’s law: 50% each year Projected Introduction

  9. Introduction

  10. What is Next Big Thing? • I wish I have the answer • Technology • Wireless broadband networks • Optical switching networks (?) • Application • VOIP • Peer-to-peer applications • Online gaming • Sony’s EverQuest servers host 600,000 PC gamers Introduction

  11. What will be covered? • Network architecture, services, apps • TCP/IP • Protocol details • Algorithms • Performance analysis • Ethernet, Wireless networks • Multimedia networks • QoS scheduling • Signaling • Network security • Basic knowledge • Attacks and counter-measures • Network management Introduction

  12. What will not be covered? • Socket programming (chap 2.7-2.9) • Physical layer technologies (chap 1.4) • Cellular networks • Multicast routing (chap 4.7) • ATM, frame relay, PPP (chap 5.7-5.8) The emphasis is no only on “how” but also “why” • Knowledge base • Reasoning behind the design Introduction

  13. Logistics • Textbook, reference book • Office hour • Homework, project policy • Grade • Prerequisite test: • What are the OSI-ISO layers? How is it related to the practice in the Internet? • What is protocol? • What is the difference between packet switching and circuit switching? • Sockets Introduction

  14. Introduction • Overview of the course • Basic concepts and structures in computer networking • Network architecture Introduction

  15. router workstation server mobile local ISP regional ISP company network What’s the Internet: “nuts and bolts” view • End systems • Host computer • Network applications • Access networks • Local area networks • communication links • Network core: • routers • network of networks Introduction

  16. 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 Introduction

  17. Network Components (Examples) Links Interfaces Switches/routers Ethernet card Large router Fibers Wireless card Coaxial Cable Switch Introduction

  18. Juniper Routers Introduction

  19. roughly hierarchical at center: “tier-1” ISPs (e.g., MCI, Sprint, AT&T, Cable and Wireless), national/international coverage treat each other as equals NAP Tier-1 providers also interconnect at public network access points (NAPs) Tier-1 providers interconnect (peer) privately Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP Introduction

  20. Seattle DS3 (45 Mbps) OC3 (155 Mbps) OC12 (622 Mbps) OC48 (2.4 Gbps) Tacoma New York Stockton Cheyenne Chicago Pennsauken Relay Wash. DC San Jose Roachdale Kansas City Anaheim Atlanta Fort Worth Orlando Tier-1 ISP: e.g., Sprint Sprint US backbone network Introduction

  21. “Tier-2” ISPs: smaller (often regional) ISPs Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs NAP Tier-2 ISPs also peer privately with each other, interconnect at NAP • Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet • tier-2 ISP is customer of tier-1 provider Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP Introduction

  22. “Tier-3” ISPs and local ISPs last hop (“access”) network (closest to end systems) Tier 3 ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP NAP Local and tier- 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP Introduction

  23. a packet passes through many networks! Tier 3 ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP NAP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Internet structure: network of networks Tier 1 ISP Tier 1 ISP Tier 1 ISP Introduction

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