Day 03 -The InternetDay 03 The Internet1Chapter 1Chapter 1IntroductionC mp t N t kin : A note on the use of these ppt slides:We’re making these slides freely available to all (faculty, students, readers). Computer Networking: A Top Down Approach Featuring the Internet, 4thInternational gy(y )They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: If you use these slides (e.g., in a class) in substantially unaltered form, th t ti th i ( ft ll ’d lik l t b k!)edition.Jim Kurose, Keith RossAddison-Wesleythat you mention their source (after all, we’d like people to use our book!) If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material.Thanks and enjoy! JFK/KWR2Thanks and enjoy! JFK/KWRAll material copyright 1996-2004J.F Kurose and K.W. Ross, All Rights ReservedWhat’s the Internet: “nuts and bolts” view millions of connected computing devices: hosts, routerworkstationcomputing devices hosts, end-systems PCs, workstations, serversPDAs ph n s t st slocal ISPservermobilePDAs, phones, toastersrunning network appscommunication linksregional ISPcommunication links fiber, copper, radio, satellitetransmission rate = regional ISPtransmission rate = bandwidthrouters:forward packets (h k f d )company3(chunks of data)network“Cool” internet appliancesCool nternet appl ancesIP picture frameIP picture framehttp://www.ceiva.com/World’s smallest web serverhttp://wwwccs cs umass edu/ shri/iPic htmlWeb-enabled toaster+weather forecasterhttp://www.theregister.co.uk/2001/03/30/java_toaster_prints_weather_forecast/http://www.theregister.co.uk/2001/06/04/bread_as_a_display_device/4http://www-ccs.cs.umass.edu/~shri/iPic.htmlWhat’s the Internet: “nuts and bolts” viewprotocolscontrol sending, receiving of msgsrouterworkstationreceiving of msgs e.g., TCP, IP, HTTP, FTP, PPPInternet: “network of local ISPservermobilenetworks” loosely hierarchicalpublic Internet versus regional ISPpublic Internet versus private intranet Internet standardsregional ISP RFC: Request For Comments IETF: Internet Engineering Task Forcecompany5networkWhat’s the Internet: a service view communication infrastructure enables fdistributed applications: Web, email, games, e-commerce database voting commerce, database, voting, file (MP3) sharing communication services id d t s:provided to apps: connectionless connection-oriented6What’s a protocol?What s a protocol?a human protocol and a computer network protocol:Sawatdee kaTCP connectionSawatdee krupWhat’s theTCP connectionreqTCP connectionresponseWhat s thetime?10:00responseGet http://www.awl.com/kurose-ross<file><file>time7What’s a protocol?What s a protocol?network protocols:network protocols: all communication activity in Internet governed by protocolsgypprotocols define:formatorder of msgs sent, received actions taken on msg transmission, receipt8A closer look at network structure:network edge:network edge:applications and hosts network core: routers network of networks9The network edge:The network edge end systems (hosts): l  run application programs e.g. Web, email at “edge of network”g client/server model e.g. Web browser/server; il li t/email client/server Distributed applicationspeer-peer model:peerpeer model minimal (or no) use of dedicated serverse g Skype KaZaA10e.g. Skype, KaZaANetwork edge: connection-oriented servicegGoal:data transfer TCP service[RFC 793]Goal:data transfer between end systemshandshaking:setup a f d TCP service[RFC 793]reliable, in-orderbyte-stream data transferconnection for data transfer ahead of time loss: acknowledgements and retransmissions TCP - Transmission Control Protocol ’ i Internet’s connection-oriented service11Network edge: connectionless servicegGoal:data transfer between end systemsGoal:data transfer between end systems UDP - User Datagram Protocol [RFC 768]: No handshaking – less work! Less delay  Internet’s connectionless service•unreliable data transferunr a ata transf r12The Network CoreThe Network Core mesh of interconnected froutersthefundamental stih is dt question:how is data transferred through net?circuit switching:c rcu t sw tch ngdedicated circuit per call: telephone netktit hidt  packet-switching:data sent thru net in discrete “chunks”13Network Core: Circuit SwitchinggEnd-end resources Endend resources reserved for “call” link bandwidth, switch capacity dedicated resourcesiitlik  circuit-like (guaranteed) performancep call setup required14Network Core: Circuit Switchinggnetwork resources ( bdidth)  dividing link bandwidth “”(e.g., bandwidth) divided into “pieces”pieces allocated to callsinto “pieces” Frequency Division Multiplexing (FDM)pieces allocated to calls resource piece idleif not used by owning call Multiplexing (FDM) Time Division Multiplexing (TDM)yg(no lending)15Circuit Switching: FDM and TDMC rcu t Sw tch ng FDM and DMFDM4usersExample:frequency4 usersfrequencytimeTDMfrequency16timePacket Switching: Statistical MultiplexinggpgAC10 MbsEthernetstatistical multiplexingB1.5 MbspgBqueue of packetswaiting for outputlinkDESequence of A & B packets does not have fixed pattern Îstatistical multiplexing.(In TDM each host would get same slot in revolving 17(In TDM each host would get same slot in revolving TDM frame.)Packet-switched networks: forwardingGoal:move packets through routers from source to destinationdestination No reservation of resources datagram network (Internet):g routes may change during session analogies: USPostal mail, asking directions when driving virtual circuit network (X 25 frame relay ATM):virtual circuit network (X.25, frame relay, ATM): fixed path determined at call setup time, remains fixed thru call ll routers maintainper-call state18Network TaxonomyTelecommunicationnetworksCircuit-switchedPacket-switchednetworksnetworksDFDMTDMNetworkswith VCsDatagramNetworksTelephonesInternetTelephonesInternet19Access networks and physical mediapyQ: How to connect end systems to edge