chapter 1 computer networks and the internet24487new

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1、CSB051–ComputerNetworks電腦網路Chapter1ComputerNetworksandtheInternet吳俊興國立高雄大學資訊工程學系Outline1.1WhatistheInternet?1.2Networkedge1.3Networkcore1.4Accessnetworksandphysicalmedia1.5ISPsandInternetbackbones1.6Delay&lossinpacket-switchednetworks1.7Protocollayersandthei

2、rservicemodels1.8History1-2What’stheInternet:“nutsandbolts”viewAworldwidenetworkthatrouterworkstationinterconnectsmillionsofcomputingdevicesservermobileßmillionsofconnectedcomputinglocalISPdevices:hosts=endsystemsßrouters:forwardpacketsregionalISP(chunksofda

3、ta)ßcommunicationlinksüfiber,copper,radio,satelliteßrunningnetworkappscompanyßprotocolscontrolsending,networkreceivingofmsgs1-3What’saprotocol?humanprotocols:networkprotocols:ß“what’sthetime?”ßmachinesratherthanß“Ihaveaquestion”humansßintroductionsßallcommun

4、icationactivityinInternetgovernedbyprotocols…specificmsgssent…specificactionstakenprotocolsdefineformat,whenmsgsreceived,orderofmsgssentandorothereventsreceivedamongnetworkentities,andactionstakenonmsgtransmission,receipt1-4RFC(RequestforComments)ßIETFühttp:

5、//www.rfc-editor.org/rfc-index2.htmlühttp://www.rfc-editor.org/rfcxx00.htmlßRFC791:IP(InternetProtocol)ßRFC793:TCP(TransmissionControlProtocol)ßRFC768:UDP(UserDatagramProtocol)ßRFC854:TELNETßRFC959:FTP(FileTransferProtocol)ßRFC821:SMTP(SimpleMailTransferProt

6、ocol)ßRFC1034/1035:DNS(DomainNameSystem)ßRFC1939:POP3(PostOfficeProtocol)ßRFC2131:DHCP(DynamicHostConfigurationProtocol)ßRFC2616:HTTP(HypertextTransferProtocol)ßRFC1631:NAT(NetworkAddressTranslator)1-5Outline1.1WhatistheInternet?1.2Networkedge1.3Networkcore1

7、.4Accessnetworksandphysicalmedia1.5ISPsandInternetbackbones1.6Delay&lossinpacket-switchednetworks1.7Protocollayersandtheirservicemodels1.8History1-6Acloserlookatnetworkstructure:ßnetworkedge:applicationsandhostsßnetworkcore:üroutersünetworkofnetworksßaccessn

8、etworks,physicalmedia:communicationlinks1-7Thenetworkedge:ßendsystems(hosts):ürunapplicationprogramsüe.g.Web,emailüat“edgeofnetwork”ßclient/servermodelüclienthostrequests,receivesservicefromalwa