《计算机网络与因特网》课件第二十章网络互联：概念、结构与协议

?计算机网络与因特网?课件第二十章网络互联：概念、结构与协议PARTIIIInternetworkingChapter20Internetworking:Concepts,Architecture,andProtocols网络互联：概念、结构与协议20.4UniversalServiceInAHeterogeneousWorld

异构世界中的通用效劳

Electricalincompatibilitiesamongnetworkhardware.Differenttechnologiesuseincompatiblepacketformatsandaddressingscheme.Aframecreatedforonenetworktechnologycannotbetransmittedonanetworkthatusesadifferenttechnology.20.5InternetworkingCalledinternetworking,theschemeusesbothhardwareandsoftware.Additionalhardwaresystemsareusedtointerconnectasetofphysicalnetwork.Softwareonalltheattachedcomputersthenprovidesuniversalservice.Theresultingsystemofconnectedphysicalnetworksisknownasaninternetworkorinternet.20.6PhysicalNetwork

ConnectionWithRouters

用路由器连接物理网Thebasichardwarecomponentusedtoconnectheterogeneousnetworkisarouter.20.7InternetArchitecture

互联网体系结构

Ainternetconsistsofasetofnetworksinterconnectedbyrouters.20.8AchievingUniversalserviceToprovideuniversalserviceamongallcomputersonaninternet,Routersmustagreetoforwardinformationfromasourceononenetworktoaspecifieddestinationonanother.20.9AVirtualNetwork虚拟网络

aninternetisavirtualnetworksystem.20.10ProtocolsForInternetworking

WorkonTCP/IPbeganinthe1970s.TCP/IPwasthefirstsetofprotocolsdevelopedforuseinaninternet.20.12LayeringandTCP/IPProtocols

TCP/IPlayeringmodel,orInternetlayeringModel,orInternetReferenceModel.20.13Hostcomputers,Routers,andProtocolLayers

Hostcomputertorefertoanycomputersystemthatconnectstoaninternetandrunsapplications.BothhostsandroutersneedTCP/IPprotocolsoftware.Routersdonotuseprot