CSCI 4550/8556 Computer Networks Comer, Chapter 1: Introduction

How do computer networks and internets operate? Network: a system for connecting computers using a single transmission technology Internet: a set of networks connected by routers that are configured to pass traffic among any computers attached to networks in the set Data transmission - network media and data encoding Packet transmission – data exchange over a network Internetworking – universal service over a collection of networks Network applications – programs that use an internet

Explosive Growth New phenomenon - now, networks are an important part of everyday activities: Business Home Government Education The global Internet is growing exponentially: Initially, a research project with a few dozen sites Today, millions of computers and thousands of networks world-wide

Internet Has its roots in the military network called Arpanet Fundamental changes from centralized to distributed computing Incorporated features for reliability and robustness Multiple links Distributed routing Ethernet made local networking feasible TCP/IP protocol made internetworking possible Developed after Arpanet Switchover occurred in 1983 Exponential growth - doubling every 18 months

Economic Impact A large industry has grown around: Networking hardware Computers Software Companies must integrate the planning, implementation, management and upgrade of their networks

Complexity Computer networking is complex: Many different hardware technologies Many different software technologies All can be interconnected in an internet No underlying theory Terminology can be confusing TLAs Industry redefines or changes terminology from academia New terms invented all the time

Abstractions and Concepts We will concentrate on abstractions and concepts to unravel complexity Examples: The types of LAN wiring, rather than the details of LAN data transmission The definition and concept of congestion, rather than specific congestion control mechanisms

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