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Introduction

Introduction. Computer Networks Fall 2005. Computer Networks. Network : system for connecting computers using a single transmission technology An internet : set of networks connected by routers that are configured to pass traffic among any computers attached to networks in the set

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Introduction

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  1. Introduction Computer Networks Fall 2005

  2. Computer Networks • Network: system for connecting computers using a single transmission technology • An internet: set of networks connected by routers that are configured to pass traffic among any computers attached to networks in the set • Data transmission - media, data encoding • Packet transmission - data exchange over a network • Internetworking - universal service over a collection of networks • Network applications - programs that use an internet

  3. Networking Growth • New phenomenon - now, networks are an important part of everyday activities • Business • Home • Government • Education • Global Internet growing exponentially • Initially (2 decades ago) a research project with a few dozen sites • Today, millions of computers and hundreds of thousands of networks world-wide

  4. Huge Impact • Societal • apparent in TV and Magazine advertisement • Economic • telecommuting, new large industry segments • Computer Science • Distributed computing • Data storage and computer architecture

  5. Some History • Advanced Research Projects Agency initiated project to connect researchers with computers • Motivated by the need for remote access to expensive resources • Adopted new technology: • Packet switching • Data transmitted in small, independent pieces • Source divides outgoing messages into packets -- Destination recovers original data • Each packet travels independently • Includes enough information for delivery -- May follow different paths -- Can be retransmitted if lost • Internetworking • Internetworking glues together networks of dissimilar technologies with routers -- Result is virtual network whose details are invisible

  6. Internet History • ARPANET began in late 1960s (not using TCP/IP) • TCP/IP developed in late 1970s • ARPANET switched to TCP/IP in early 80s • Start of public Internet (early 1990’s) • Few hundred computers • Few tens of networks

  7. Internet Growth(Number of Computers Attached to the Internet)

  8. Internet Growth (log scale) Number of connected hosts is approximately doubling every 18 months

  9. Topic Complexity • Computer networking is complex • Many different hardware technologies • Ethernet, Token ring, ATM, Fibre Channel, etc. • Many different software technologies • TCP/IP, Apple talk, etc. • All can be interconnected in an internet • Terminology can be confusing • Abbreviations are very common • Industry redefines or changes terminology • New terms invented all the time • To unravel complexity, in the course, we will concentrate on concepts rather than details of specifics mechanisms

  10. Simple Tools • Ping • Traceroute

  11. Course Website/Syllabus http://myqu.qu.edu.qa/courses/Networks

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