Spring 2000John Kristoff1 Introduction Computer Networks

Spring 2000John Kristoff2 Motivation and Scope Computer networks and internets: an overview of concepts, terminology and technologies that form the basis for digital communication in private corporate networks the the global Internet.

Spring 2000John Kristoff3 Motivation for Networks ÑInformation Access ÑSharing of Resources ÑFacilitate Communications

Spring 2000John Kristoff4 What a Network Includes ÑTransmission hardware ÑSpecial-purpose hardware devices Ñinterconnect transmission media Ñcontrol transmission Ñrun protocol software ÑProtocol software Ñencodes and formats data Ñdetects and corrects problems

Spring 2000John Kristoff5 What a Network Does ÑProvides communication that is ÑReliable ÑFair ÑEfficient ÑFrom one application to another

Spring 2000John Kristoff6 What a Network Does [continued] ÑAutomatically detects and corrects ÑData corruption ÑData loss ÑDuplication ÑOut-of-order delivery ÑAutomatically finds optimal path from source to destination

Spring 2000John Kristoff7 Data Communication versus Networking Ñ With only two nodes, mostly EE issues. Ñ With more than two nodes, lot more issues!

Spring 2000John Kristoff8 Direction of Transmission Point to PointBroadcast

Spring 2000John Kristoff9 Network Topologies

Spring 2000John Kristoff10 Transmission Media Ñ Wireline Ñ String Ñ Garden Hose Ñ Copper Ñ Twisted Pair Ñ Coax Ñ Optical Fiber Ñ Wireless Ñ Sound Ñ Light and mirrors Ñ Infrared Ñ RF Ñ Microwave

Spring 2000John Kristoff11 Network Scope ÑLocal Area Network (LAN) ÑMetropolitan Area Network (MAN) ÑWide Area Network (WAN)

Spring 2000John Kristoff12 Data Transmission Serial Parallel

Spring 2000John Kristoff13 Multiplexing

Spring 2000John Kristoff14 Communication Modes ÑSimplex ÑHalf-duplex ÑFull-duplex

Spring 2000John Kristoff15 Connection-oriented versus Connectionless Ñ Connection Setup Ñ Data Transfer Ñ Connection Termination Ñ Data Transfer

Spring 2000John Kristoff16 Circuit Switching versus Packet Switching Ñ Dedicated Ñ fixed bandwidth Ñ route fixed at setup Ñ idle capacity wasted Ñ network state Ñ Best Effort Ñ end-to-end control Ñ multiplexing technique Ñ re-route capability Ñ congestion problems

Spring 2000John Kristoff17 Examples ÑPublic Switched Telephone Network ÑInternet ÑPostal Service ÑTrain ÑCar and highway system

Spring 2000John Kristoff18 Standards ÑHardware ÑSoftware ÑProtocols ÑAdvantages and Disadvantages ÑProprietary, De Facto, De Jure ÑStandards Bodies ÑIETF, IEEE, OSI, ANSI, ATM Forum, etc.

Spring 2000John Kristoff19 Protocols ÑRules, standards and etiquette ÑMetric System ÑEnglish ÑDinner party ÑMorse Code ÑTCP/IP ÑHTML

Spring 2000John Kristoff20 Layering

Spring 2000John Kristoff21 Headers, Data and Trailers

Spring 2000John Kristoff22 Encapsulation

Spring 2000John Kristoff23 ISO OSI Reference Model Ñ7: Application Layer Ñ6: Presentation Layer Ñ5: Session Layer Ñ4: Transport Layer Ñ3: Network Layer Ñ2: Data link Layer Ñ1: Physical Layer

Spring 2000John Kristoff24 Interfaces and Services ÑPDUs ÑSDUs ÑSAPs ÑPeer communications ÑService Primitives Ñetc... read Tanenbaum and 1.3.5

Spring 2000John Kristoff25 TCP/IP Model Ñ5: Application Layer Ñ4: Transport Layer Ñ3: Network Layer Ñ2: Data link Layer Ñ1: Physical Layer

Spring 2000John Kristoff26 TCP/IP versus OSI  "Rough consensus and running code ” ÑSimplicity ÑTime to market ÑAvailability

Spring 2000John Kristoff27 Network Classification ÑPhysical medium: copper, fiber, wireless ÑScope: LAN, MAN, WAN ÑTopology: bus, star, ring, mesh ÑSwitching style: circuit, packet ÑApplication: voice, data, video ÑProtocol: IP, OSI, Ethernet, ATM ÑTransmission rate: 10Mb/s, Gigabit

Spring 2000John Kristoff28 Terms I (we) Often Use ÑFrames: think data link layer ÑPackets: think network layer ÑDatagrams: think IP ÑSegments: think TCP ÑCells: think ATM ÑLayer : refer to reference models

Spring 2000John Kristoff29 The End-to-End Argument  "End-to-End Arguments in System Design ” ÑJ.H. Saltzer, D.P. Reed, and D.D. Clark Ñ