2-1©2005 Raj JainCSE473sWashington University in St. LouisData Communications Data Communications and and Networking OverviewNetworking OverviewRaj Jain Washington UniversitySaint Louis, MO [email protected] slides are available on-line at:http://www.cse.wustl.edu/~jain/cse473-05/2-2©2005 Raj JainCSE473sWashington University in St. LouisOverviewOverview! Data Comm vs Networking vs Distributed Systems ! Communications Tasks! Types of Networks! Protocol Layers! ISO/OSI Reference Model! TCP/IP Reference Model2-3©2005 Raj JainCSE473sWashington University in St. LouisData Communication vs NetworkingData Communication vs Networking! Communication: Two Nodes. Mostly EE issues.! Networking: Two or more nodes. More issues, e.g., routing2-4©2005 Raj JainCSE473sWashington University in St. LouisDistributed Systems vs NetworksDistributed Systems vs Networks! Distributed Systems: ! Users are unaware of underlying structure. E.g., trn instead of \n\bone\0\trn! Mostly operating systems issues. ! Nodes are generally under one organization’s control.! Networks: Users specify the location of resources. http:\\www.cse.wustl.edu\~jain\! Nodes are autonomous.ServerServer2-5©2005 Raj JainCSE473sWashington University in St. LouisSimplified Communications ModelSimplified Communications Model! Transmitter: encodes the information2-6©2005 Raj JainCSE473sWashington University in St. LouisData Communications: ExampleData Communications: Example! Modem is used to transmit/receive digital information over analog phone system2-7©2005 Raj JainCSE473sWashington University in St. LouisCommunications TasksCommunications Tasks! Transmission System Utilization (Multiplexing)! Interfacing! Signal generation (Coding)! Synchronization between transmitter and receiver! Exchange management (Connection Management)! Error detection and correction! Flow control! Addressing! Routing! Recovery! Message formatting! Security! Network Management2-8©2005 Raj JainCSE473sWashington University in St. LouisTypes of NetworksTypes of Networks! Point to point vs Broadcast! Circuit switched vs packet switchedWAN Bus LANRingLAN2-9©2005 Raj JainCSE473sWashington University in St. LouisTypes of Networks (Cont)Types of Networks (Cont)! Enterprise vs Telecom NetworksEthernet is the most common interface in EnterpriseFrame relay and ATM are common in Telecom Networks! Local Area Networks (LAN) 0-2 km, Single OwnershipMetropolitan Area Networks (MAN) 2-50 km, Wide Area Networks (WAN) 50+ km! Telecom Networks:! Access: Between subscriber and the service provider! Metro: Covering a city! Core: Between cities2-10©2005 Raj JainCSE473sWashington University in St. LouisAn Example ConfigurationAn Example Configuration2-11©2005 Raj JainCSE473sWashington University in St. LouisProtocol LayersProtocol LayersPhilosopherTranslatorSecretaryI believe there is a God!! Problem: Philosophers in different countries speak different languages. The Telex system works only with English.2-12©2005 Raj JainCSE473sWashington University in St. LouisA Sample Protocol ArchitectureA Sample Protocol Architecture2-13©2005 Raj JainCSE473sWashington University in St. LouisISO/OSI Reference ModelISO/OSI Reference ModelApplicationPresentationSessionTransportNetworkDatalinkPhysicalHow to transmit signal: CodingTwo party communication: EthernetRouting, Addressing: IPEnd-to-end communication: TCPFile transfer, Email, Remote LoginASCII Text, SoundEstablish/manage connection1232-14©2005 Raj JainCSE473sWashington University in St. LouisService and Protocol Data UnitsService and Protocol Data Units! Service Access Points (SAPs)! Service Data Units (SDUs)! Protocol Data Units (PDUs)Application 1TransportNetwork AccessApplication 2 Application 1TransportNetwork AccessApplication 2PDUSDU2-15©2005 Raj JainCSE473sWashington University in St. LouisService Data Unit (SDU)Service Data Unit (SDU)ApplicationPresentationSessionTransportNetworkDatalinkPSDUSSDUTSDUNSDUDSDUPhSDUPhysical2-16©2005 Raj JainCSE473sWashington University in St. LouisProtocol Data Unit (PDU)Protocol Data Unit (PDU)ApplicationPresentationSessionTransportNetworkDatalinkPhysicalAPDU, MessagePPDUSPDUTPDUNPDU, PacketDPDU, FramePhPDU, FrameApplicationPresentationSessionTransportNetworkDatalinkPhysical2-17©2005 Raj JainCSE473sWashington University in St. LouisUse of a RelayUse of a Relay2-18©2005 Raj JainCSE473sWashington University in St. LouisService PrimitivesService Primitives! Indication = Interrupt1. Request2. IndicationHigher LayerLower LayerHigher LayerLower Layer1 2343. Response4. ConfirmUnconfirmed service: No confirmation or response2-19©2005 Raj JainCSE473sWashington University in St. LouisTCP/IP Reference ModelTCP/IP Reference Model! TCP = Transport Control Protocol! IP = Internet Protocol (Routing)InternetworkHost to NetworkIPEthernetApplicationTransportFTPTCPTelnet HTTPUDPPacketRadioPoint-to-PointTCP/IP Ref Model TCP/IP ProtocolsPhysical Coax Fiber Wireless2-20©2005 Raj JainCSE473sWashington University in St. LouisOSI vs TCP/IPOSI vs TCP/IP2-21©2005 Raj JainCSE473sWashington University in St. LouisOSI vs TCP Reference ModelsOSI vs TCP Reference Models! OSI introduced concept of services, interface, protocols. These were force-fitted to TCP later ⇒ It is not easy to replace protocols in TCP. ! In OSI, reference model was done before protocols.In TCP, protocols were done before the model! OSI: Standardize first, build laterTCP: Build first, standardize later! OSI took too long to standardize. TCP/IP was already in wide use by the time.! OSI became too complex.! TCP/IP is not general. Ad hoc.2-22©2005 Raj JainCSE473sWashington University in St. LouisTCP/IP ConceptsTCP/IP Concepts! Network Attachment Point (NAP)Sub Sub2-23©2005 Raj JainCSE473sWashington University in St. LouisPDUsPDUsin TCP/IP Architecturein TCP/IP ArchitectureSubSub2-24©2005 Raj JainCSE473sWashington University in St. LouisTCP/IP ApplicationsTCP/IP Applications2-25©2005 Raj JainCSE473sWashington University in St. LouisSummarySummary! Communication, Networks, and Distributed systems! ISO/OSI’s 7-layer reference model! TCP/IP has a 5-layer model! PDU, SDU, SAP! Request, Indication, Response, Confirmation2-26©2005 Raj JainCSE473sWashington University in St. LouisReading AssignmentReading Assignment! Read Chapters 0, 1, and 2 of Stallings 7th EditionAppendix 2A can be skipped at this time! 0.2 Internet and Web Resources! 0.3 Standards! Visit some of the web sites mentioned in 0.2 and 0.32-27©2005 Raj