The International Standards Organization Reference Model ofOpen System Interconnection (ISO OSI model)Host AHostBApplicationMessageinterfacesPresentationMessageinterfacesSessionMessageSubnetTransportMessageBoundaryNetworkPacketData LinkFrameBitPhysical
The International Standards Organization Reference Model of Open System Interconnection (ISO OSI model) Application Presentation Session Transport Network Data Link Physical interfaces interfaces Host A Host B Subnet Boundary Message Message Message Message Packet Frame Bit
ISO OSI Model (The 7 Layers)Physical Layerspecifies physical signals (electrical, optical), cabling/wiringData Link Layerframe boundaries, errordetection(noise),flow controlNetwork Layerhow packets are sent from sources to destinations:routing, congestion control,internetworking.Transport Layerbreak messages into packets, multiplex/demultiplex messages,end-to-end reliabilitySession Layerprovides users interface: directory,access rights, synchronization.PresentationLayerdata encryption,data compression, code conversionApplicationLayervirtualterminal,virtualfiletransfer
ISO OSI Model (The 7 Layers) Physical Layer specifies physical signals (electrical, optical), cabling/wiring. Data Link Layer frame boundaries, error detection (noise), flow control Network Layer how packets are sent from sources to destinations: routing, congestion control, internetworking. Transport Layer break messages into packets, multiplex/demultiplex messages,end-to-end reliability. Session Layer provides users interface: directory, access rights, synchronization. Presentation Layer data encryption, data compression, code conversion. Application Layer virtual terminal, virtual file transfer
Implementation of LayeringInformationTransferApplicationMessagelayerPresentationConversionConvertedMessageSessionlayerTransportPacketPktHdrFirstPktPktHdr SecondPktlayerFrameFrameHdrPktHdrFirstPktFrameHdr PktHdr SecondPktlayerPhysicalFramessentoutontonetworklayer
Implementation of Layering Application layer Conversion layer Packet layer Frame layer Physical layer Frame Hdr Pkt Hdr Message Converted Message First Pkt Pkt Hdr Second Pkt Pkt Hdr First Pkt Frame Hdr Pkt Hdr Second Pkt Frames sent out onto network Information Transfer Presentation Session Transport
Common Network ProtocolsEthernet(IEEE802.3)10Mbps-CarrierSenseMultipleAccess/CollisionDetectToken-Bus (IEEE802.4)-Physicallyabus,logically aring,tokenpassingToken-Ring (IEEE 802.5)4-16MbpsRingtopology,tokenpassingSlotted Aloha-Time slot, boardcastingSlotted-ring (Cambridge ring)TimemultiplexingFibreDistributedDataInterface(FDDI)- High speed (100Mbps), token-bus like protocolIntegratedServiceDigitalNetwork(ISDN)- Multiples of 64kbps, up to 2 Mbps per channel for voice & videoATM Switch (155Mbps,622Mbps)Fast Ethernet(100Mbps), Giga-bit Ethernet(1Gbps)
Common Network Protocols • Ethernet (IEEE 802.3) 10Mbps − Carrier Sense Multiple Access / Collision Detect • Token-Bus (IEEE 802.4) − Physically a bus, logically a ring, token passing • Token-Ring (IEEE 802.5) 4-16Mbps − Ring topology, token passing • Slotted Aloha − Time slot, boardcasting • Slotted-ring (Cambridge ring) − Time multiplexing • Fibre Distributed Data Interface (FDDI) − High speed (100Mbps), token-bus like protocol • Integrated Service Digital Network (ISDN) − Multiples of 64kbps, up to 2 Mbps per channel for voice & video • ATM Switch (155 Mbps, 622Mbps) • Fast Ethernet (100Mbps), Giga-bit Ethernet (1Gbps)
Popular protocols for PCDoDIBMNetware/Novell7 - Application6 - Presentation5 - SessionSPXTCP4 - TransportUDPNetBIOS3-NetworkIPIPXUDp:User Datagram Protocol2 - Data LinkNetworkCardTcP:Transmission Control ProtocolIP:InternetProtocolSpx:Sequenced Packet eXchange1 - PhysicalIPX:Internetwork Packet eXchange
Popular protocols for PC 7 - Application 6 - Presentation 5 - Session 4 - Transport 3 - Network 2 - Data Link 1 - Physical Network Card UDP TCP SPX IP IPX NetBIOS DoD Netware/Novell IBM UDP:User Datagram Protocol TCP:Transmission Control Protocol IP:Internet Protocol SPX:Sequenced Packet eXchange IPX:Internetwork Packet eXchange