Walrand Lecture 1EECS 228aEECS 228a – Lecture 1Overview: Networks*Pravin VaraiyaShyam Parekhwww.eecs.berkeley.edu/~varaiyaFall 2003* These notes were created by Prof. Walrand, F’02EECS228a - Walrand 2Course InformationInstructors: Pravin Varaiya, OH:Tu,Th 4:00-5:00, 271M Cory Shyam Parekh, OH: Tu,Th 4:00-5:00, 463 CoryTime/Place:Tu,Th 2:00-3:30 in 299 CoryHome Page: http://www-inst.eecs.berkeley.edu/~ee228aEECS228a - Walrand 3TopicsOverview [1 week]Economics of Networks [4]802.11 and Sensor Networks [4]Congestion Control [2.5]Traffic Models [2.5]Review [1]Theoretical backgroundState of the art EECS228a - Walrand 4DetailsGrading: Class participation & presentations: 65% Project: 35% - Original research on selected topicMaterial: Lecture Slides and Notes Research PapersEECS228a - Walrand 5OverviewNetwork ExamplesNetwork ComponentsInternetworkingInternetOther NetworksPacketsTransportWeb BrowsingTelephone CallResource Sharing – MultiplexingProtocolsIETFEECS228a - Walrand 6Network ExamplesTeleglobe Communications Corporation – Fiber + SatelliteWalrand Lecture 1EECS 228aEECS228a - 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 CableLinksWirelessWalrand Lecture 1EECS 228aEECS228a - Walrand 13Network ComponentsEthernet Network Interface CardEECS228a - Walrand 14Network ComponentsEthernetEECS228a - Walrand 15Network ComponentsEthernet is a broadcast-capable, multi-accessLANLink: EthernetEECS228a - Walrand 16Network ComponentsIEEE 802.11 WLAN is adaptation of Ethernet like protocol for wireless mediumLink: IEEE 802.11 WLANLaptopLaptop LaptopIndependent Basic Service Set (IBSS)EECS228a - Walrand 17IEEE 802.11 WLAN ProductsAccess PointsPC CardsEECS228a - Walrand 183G UMTS Cellular NetworkConvergence of Voice and Data“Mobile Network Evolution: A Revolution on the Move,” J. De Vriendt, et al.,IEEE Comm. Magazine, April 2002.Walrand Lecture 1EECS 228aEECS228a - Walrand 19Network ComponentsTelephone Switch Large RouterEECS228a - Walrand 20Network with RoutersLANs interconnected by routersLAN1LAN2LAN3InternetR1R2R3R4EECS228a - Walrand 21InternetworkingProvides 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 22The InternetA global network of networks all using a common protocol (IP, the Internet Protocol)One 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 23Scale of Internet• Data from www.nw.comEECS228a - Walrand 24Other NetworksThe Telephone NetworkProcessor Interconnection NetworksATM NetworksCable-TV NetworksWalrand Lecture 1EECS 228aEECS228a - Walrand 25PacketsABA | B | ...B → port 2123A | B | ...A | B | ...EECS228a - Walrand 26Packets: Main IdeasThe switches (routers) have no memory of packets: scalabilityThe network is independent of the applications: flexibilityThe packet formats and addresses are independent of the technology: extensibilityEECS228a - Walrand 27TransportPacketsACKsEECS228a - Walrand 28Web Browsing:top-down viewExampleLocating Resource: DNSConnectionEnd-to-endPacketsBitsPoints to rememberEECS228a - Walrand 29Click Link or URL get content from localor remote computerURL:http://www.google.com/stringSpecifies- Protocol: http- Computer: www.google.com- String: computer (server) selects contents based on stringWeb: ExampleEECS228a - Walrand 30Web: 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?Walrand Lecture 1EECS 228aEECS228a - Walrand 31Web: ConnectionThe protocol (http) sets up a connection between the host and www.google.com to transfer the pageThe connection transfers the page as a byte stream, without errors: pacing + error controlHostwww.google.comconnectOKget pagepage; closeEECS228a - Walrand 32Web: 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 33Web: 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 34Web: 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 35Web: Points to rememberSeparation of tasks send 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]Scalability routers don’t know about connections names and addresses are hierarchicalEECS228a - Walrand 36Telephone CallTelephone NetworkDialing a NumberSetting up a CircuitPhone ConversationReleasing the CircuitWalrand Lecture 1EECS 228aEECS228a - Walrand 37Telephone Network5ESS (Lucent)DMS100 (Nortel)EECS228a - Walrand 38Telephone NetworkEECS228a - Walrand 39Telephone NetworkLogic Diagram:EECS228a - Walrand 40Dialing a NumberA Off-HookS1 ListensA
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