NetworkArchitectureNetworksarecomplex!! Dealing with complex systems:explicit structure allows identification,relationship of complex system'spieceslayered reference model for discussionomodularizationeases maintenance,updatingof systemchange of implementation of layer's service transparent to rest ofsystem e.g., change in gate procedure doesn't affect rest of system
Networks are complex!! Dealing with complex systems: ◦ explicit structure allows identification, relationship of complex system’s pieces layered reference model for discussion ◦ modularization eases maintenance, updating of system change of implementation of layer’s service transparent to rest of system e.g., change in gate procedure doesn’t affect rest of system
Layered reference modelISO/OSI reference modelInternetprotocol stackapplicationapplicationpresentationtransportsessiontransportnetworknetworklinklinkphysicalphysical
Internet protocol stack ISO/OSI reference model
LayeredreferencemodelApplication layer: supporting network applications。 POP, SMTP,HTTPTransport layer: process-process data transfer。TCP,UDP Network layer: routing of datagrams from source todestination。IP, routingprotocols Link layer: data transfer between neighboring networkelements。PPP,EthernetPhysical layer: bits “on the wire
Application layer: supporting network applications ◦ POP, SMTP, HTTP Transport layer: process-process data transfer ◦ TCP, UDP Network layer: routing of datagrams from source to destination ◦ IP, routing protocols Link layer: data transfer between neighboring network elements ◦ PPP, Ethernet Physical layer: bits “on the wire
pingApplicationDNSHITPTelnetFTPSNMPapplicationLayerTCPUDPTransportLayerRouting ProtocolsICMPRIPNetworkIPPIMIGMPLayerOSPFDHCPData LinkARPEthernetLayerNetworkInterface
A layer N+1 entity sees the lower layers only as aservice providerN+1LaverPeerProtocolN+1 LayerN+1 LayerEntityEntityIndicateRequestDeliveryDeliveryServiceProvider
A layer N+1 entity sees the lower layers only as a service provider