EECS 228a – Lecture 1 Overview: NetworksCourse InformationTopicsDetailsOverviewNetwork ExamplesSlide 7Slide 8Slide 9Slide 10Network ComponentsSlide 12Slide 13Slide 14Slide 15Slide 16Network with RoutersInternetworkingThe InternetScale of InternetOther NetworksPacketsPackets: Main IdeasTransportWeb BrowsingWeb: ExampleWeb: Locating ResourceWeb: ConnectionWeb: End-to-endWeb: PacketsWeb: BitsWeb: Points to rememberTelephone CallTelephone NetworkSlide 35Slide 36Dialing a NumberSetting Up a CircuitPhone ConversationRelease CircuitsResource Sharing - MultiplexingMultiplexingTime Division Multiplexing (also called STDM --Synchronous Time Division Multiplexing)Statistical MultiplexingAnalysis of STDM/FDMAnalysis of Statistical Mux’ingProtocolsProtocol ExampleProtocol StandardsThe IETFEECS 228a – Lecture 1Overview: NetworksJean Walrandwww.eecs.berkeley.edu/~wlrFall 2002EECS228a - Walrand 2Course InformationInstructor: Jean WalrandOffice Hours: M-Tu 1:00 - 2:00Time/Place: MW 2:00-3:30 in 285 CoryHome Page:http://www-inst.eecs.berkeley.edu/~ee228aEECS228a - Walrand 3Topics Overview [1 week] Economics of Networks [4] Routing [4] Congestion Control [2.5] Traffic Models [2.5] Review [1]Theoretical backgroundState of the artEECS228a - Walrand 4Details Grading:In class presentations: 65% Project: 35% - Original research on selected topic Material:Lecture Slides and NotesResearch PapersEECS228a - Walrand 5OverviewNetwork ExamplesNetwork ComponentsInternetworkingInternetOther NetworksPacketsTransportWeb BrowsingTelephone CallResource Sharing – MultiplexingProtocolsIETFEECS228a - Walrand 6Network ExamplesTeleglobe Communications Corporation – Fiber + SatelliteEECS228a - Walrand 7Network ExamplesGlobal Crossing CorporationEECS228a - Walrand 8Network ExamplesKPNQWESTEECS228a - Walrand 9Network ExamplesWilliams CommunicationsEECS228a - Walrand 10Network ExamplesPalo Alto NetworkEECS228a - Walrand 11Network ComponentsLink: carry bits from one place to another (or maybe to many other places)Switch/router: move bits between links, forming internetworkHost: communication endpoint (workstation, PDA, cell phone, toaster, tank)EECS228a - Walrand 12Network ComponentsFibersCat5 UnshieldedTwisted PairsCoaxial CableLinksWirelessEECS228a - Walrand 13Network ComponentsEthernet Network Interface CardEECS228a - Walrand 14Network ComponentsEthernetEECS228a - Walrand 15Network ComponentsEthernet is a broadcast-capable, multi-access LANLink: EthernetEECS228a - Walrand 16Network ComponentsTelephone Switch Large RouterEECS228a - Walrand 17Network with RoutersLANs interconnected by routersLAN1LAN2LAN3InternetR1R2R3R4EECS228a - Walrand 18InternetworkingProvides message delivery between multiple networks:Subnet 1Subnet 2ISP 2ISP 1Example: Subnet 1 = network of LANs of previous slideISP 1 = Sprint, ISP 2 = MCISubnet 2 = UCB networkEECS228a - Walrand 19The InternetA global network of networks all using a common protocol (IP, the Internet Protocol)Focus of this classA challenge to understand:large scale (10’s of millions of users, 10’s of thousands of networks)heterogeneity, irregular topology, decentralized managementEECS228a - Walrand 20Scale of Internet• Data from www.nw.comEECS228a - Walrand 21Other NetworksThe Telephone NetworkProcessor Interconnection NetworksATM NetworksCable-TV NetworksEECS228a - Walrand 22PacketsABA | B | ...B port 2123A | B | ...A | B | ...EECS228a - Walrand 23Packets: Main IdeasThe switches have no memory of packets: scalabilityThe network is independent of the applications: flexibilityThe packet formats and addresses are independent of the technology: extensibilityEECS228a - Walrand 24TransportPacketsACKsEECS228a - Walrand 25Web BrowsingExampleLocating Resource: DNSConnectionEnd-to-endPacketsBitsPoints to rememberEECS228a - Walrand 26Click Link or URL get content from localor remote computerURL:http://www.google.com/stringSpecifies-Protocol: http-Computer: www.google.com-StringComputer (server) selects contents based on stringWeb: ExampleEECS228a - Walrand 27Web: Locating Resourcewww.google.com is the name of a computerNetwork uses IP addressesTo find the IP address, the application uses a hierarchical directory service called theDomain Name Systemlocalcomhostwww.google.com?IP = a.b.c.dIP = a.b.c.dwww.google.com?EECS228a - Walrand 28Web: ConnectionThe protocol (http) sets up a connection between the host and cnn.com to transfer the pageThe connection transfers the page as a byte stream, without errors: pacing + error controlH o s tc n n . c o mconnectOKget pagepage; closeEECS228a - Walrand 29Web: End-to-endThe byte stream flows from end to end across many links and switches: routing (+ addressing)That stream is regulated and controlled by both ends: retransmission of erroneous or missing bytes; flow controlEnd-to-end pacing andflow controlRoutingwww.google.comhostEECS228a - Walrand 30Web: PacketsThe network transports bytes grouped into packetsThe packets are “self-contained” and routers handle them one by oneThe end hosts worry about errors and flow control:Destination checks packet for errors (using error detection code CKS) and sends ACKs with sequence number # Source retransmits packets that were not ACKed and adjusts rate of transmissionsCA | B | # , CKS | bytesB Cwww.google.comIP address: AHostIP address: BDestinationNext HopEECS228a - Walrand 31Web: BitsEquipment in each node sends the packets as a string of bitsThat equipment is not aware of the meaning of the bits01011...011...110Transmitter Physical Medium Receiver01011...011...110OpticalCopperWirelessEECS228a - Walrand 32Web: Points to rememberSeparation of taskssend bits on a link: transmitter/receiver [clock, modulation,…]send packet on each hop [framing, error detection,…]send packet end to end [addressing, routing]pace transmissions [detect congestion]retransmit erroneous or missing packets [acks, timeout]find destination address from name [DNS]Scalabilityrouters don’t know about connectionsnames and addresses are hierarchicalEECS228a - Walrand 33Telephone CallTelephone NetworkDialing a NumberSetting up a CircuitPhone ConversationReleasing the CircuitEECS228a - Walrand 34Telephone Network5ESS (Lucent)DMS100 (Nortel)EECS228a - Walrand 35Telephone NetworkEECS228a - Walrand 36Telephone NetworkLogic Diagram:EECS228a - Walrand 37Dialing a NumberA Off-HookS1 ListensA dialsS1 RegistersABS1EECS228a - Walrand
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