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.packet
B.value
C.service
D.Paragraph
正确答案是B