ThediffservapproachtoprovidingQoSinnetworksemploysasmall,well-definedsetofbuildingblocksfromwhichyoucanbuildavarietyof(________).Itsaimistodefinethedifferentiatedservices(DS)byte,theTypeofService(ToS)bytefromtheInternetProtocolVersion4()andtheTrafficClassbytefromIPVersion6,andmarkthestandardizedDSbyteofthepacketsuchthatitreceivesaparticularforwardingtreatment,orper-hopbehavior(PH B),ateachnetworknode.Thediffservarchitectureprovidesa()withinwhichserviceproviderscanoffercustomersarangeofnetworkservices,eachdifferentiatedbasedonperformance.Acustomercanchoosethe()levelneededonapacket-by-packetbasisbysimplymarkingthepacket'sDifferentiatedServicesCodePoint(DSCP)fieldtoaspecificvalue.This()specifiesthePHBgiventothepacketwithintheserviceprovidernetwork。横线处应选()
A.services B.Users C.networks D.structures正确答案A
