Raj JainThe Ohio State University1A Review of KeyA Review of KeyNetworking ConceptsNetworking ConceptsRaj JainThe Ohio State UniversityColumbus, OH [email protected] slides are available athttp://www.cis.ohio-state.edu/~jain/cis777-99/Raj JainThe Ohio State University2q ISO/OSI Reference Modelq Ethernet/IEEE 802.3 LANsq Interconnecting DevicesAll these concepts are taught in CIS677.OverviewRaj JainThe Ohio State University3ISO/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 connection123Raj JainThe Ohio State University4TCP/IP Reference ModelTCP/IP Reference Modelq TCP = Transport Control Protocolq IP = Internet Protocol (Routing)ApplicationPresentationSessionTransportNetworkDatalinkPhysicalApplicationTransportInternetworkHost to NetworkFTPTCPIPEthernetTelnet HTTPUDPPacketRadioPoint-to-PointTCP/IP Ref Model OSI Ref ModelTCP/IP ProtocolsRaj JainThe Ohio State University5Layered Packet FormatLayered Packet Formatq Nth layer control info ispassed as N-1th layerdata.FTP DataFTP HeaderTCP DataTCPHeaderIP DataIPHeaderEthernet DataEthernetHeaderEthernetTrailerRaj JainThe Ohio State University6Coding TerminologyCoding Terminologyq Signal element: Pulseq Modulation Rate: 1/Duration of the smallest element=Baud rateq Data Rate: Bits per secondq Data Rate = Fn(Bandwidth, signal/noise ratio,encoding)PulseBit+5V0-5VRaj JainThe Ohio State University7Channel CapacityChannel Capacityq Capacity = Maximum data rate for a channelq Nyquist Theorem:q Bilevel Encoding: Data rate = 2 × Bandwidth05V❑ Multilevel coding: Data rate = 2 × Bandwidth × log2 MExample: M=4, Capacity = 4 × Bandwidth0001101110Raj JainThe Ohio State University80011Channel Capacity (Cont)Channel Capacity (Cont)q Bilevel Encoding: Worst case: 1010101010Cycle time = 2 × Bit time⇒ Data rate = 2 × Bandwidth❑ Multilevel coding: Worst case 0011001100110011Cycle time = 4 × Bit time⇒ Data rate = 2 × Bandwidth × log2 M0005V1011 110011001100Raj JainThe Ohio State University9T RData Signal Data1010Data vs SignalData vs Signalq Data: Analog (Music), Digital (files)q Signal: Analog (POTS, Radio), Digital (ISDN)Data Signal ExamplesAnalog Analog Modulation AM, FMDigital Analog Coding/Keying ASK, FSK, PSKAnalog Digital Modulation PCM, ADPCMDigital Digital Coding Manchester, NRZRaj JainThe Ohio State University10Bit StuffingBit Stuffingq Delimit with special bit pattern (bit flags)q Stuff bits if pattern appears in dataq Remove stuffed bits at destinationTransmitterReceiver0 11111 11111 11111 1001001111110 0 1111110 111110 111110 10010 011111100 11111 11111 11111 10010FlagRaj JainThe Ohio State University11Flow ControlFlow Controlq Flow Control = Sender does not flood thereceiver, but maximizes throughputq Sender throttled until receiver grants permissionq Methods:m Stop and waitm Sliding windowRaj JainThe Ohio State University12Error ControlError Controlq Error Control = Deliver frames withouterror, in the proper order to network layerq Error control Mechanisms:m Ack/Nak: Provide sender some feedback aboutother endm Time-out: for the case when entire packet or ack islostm Sequence numbers: to distinguish retransmissionsfrom originalsq ARQ: Stop and Wait, Selective Reject, Go-back nRaj JainThe Ohio State University13Connection-Oriented vsConnection-Oriented vsConnectionlessConnectionlessq Connection-Oriented: Telephone Systemm Path setup before data is sentm Data need not have address. Circuit number issufficient.q Connectionless: Postal System.m Complete address on each packetm The address decides the next hop at each routerRaj JainThe Ohio State University14Multiple Access ProtocolsMultiple Access Protocols(a) Multiple Access(b) Carrier-Sense Multiple Access with Collision DetectionRaj JainThe Ohio State University15Multiple Access ProtocolsMultiple Access Protocolsq Aloha at University of Hawaii:Transmit whenever you likeWorst case utilization = 1/(2e) =18%q CSMA: Carrier Sense Multiple AccessListen before you transmitq CSMA/CD: CSMA with Collision DetectionListen while transmitting.Stop if you hear someone else.q Ethernet uses CSMA/CD.Standardized by IEEE 802.3 committee.Raj JainThe Ohio State University16Interconnection DevicesInterconnection Devicesq Repeater: PHY device that restores dataand collision signalsq Hub: Multiport repeater + fault detection andrecoveryq Bridge: Datalink layer device connecting two ormore collision domains. MAC multicasts arepropagated throughout “extended LAN.”q Router: Network layer device. IP, IPX, AppleTalk.Does not propagate MAC multicasts.q Switch: Multiport bridge with parallel pathsThese are functions. Packaging varies.Raj JainThe Ohio State University17Interconnection DevicesInterconnection DevicesH HBH HRouterExtended LAN=Broadcast domainLAN=CollisionDomainNetworkDatalinkPhysicalTransportRouterBridge/SwitchRepeater/HubGatewayApplicationNetworkDatalinkPhysicalTransportApplicationRaj JainThe Ohio State University18IEEE 802 Address FormatIEEE 802 Address Formatq Multicast = “To all bridges on this LAN”q Broadcast = “To all stations”= 111111....111 = FF:FF:FF:FF:FF:FF❑ 48-bit:1000 0000 : 0000 0001 : 0100 0011: 0000 0000 : 1000 0000 : 0000 1100= 80:01:43:00:80:0CIndividual/GroupUniversal/Local24 bits assigned by OUI Owner1 1 2224Organizationally Unique Identifier (OUI)Raj JainThe Ohio State University19SummarySummaryq ISO/OSI reference model has seven layers.TCP/IP Protocol suite has four layers.q Ethernet/IEEE 802.3 uses CSMA/CD.q Addresses: Local vs Global, Unicast vs Broadcast.Raj JainThe Ohio State University20HomeworkHomeworkq For each of the following addresses:indicate whether it is a multicast andwhether it is a locally assigned address?80:02:45:00:00:0040:02:45:00:00:01Were these addresses assigned by the