Togetherwiththenetworklayer,thetransportlayeristheheartoftheprotocol().Thenetworklayerprovidesend-to-end()deliveryusingdatagramsorvirtualcircuits.Thetransportlayerbuildsonthenetworklayertoprovidedatatransportfromaprocessona()machinetoaprocessonadestinationmachinewithadesiredlevelofreliabilitythatisindependentofthephysical(请作答此空)currentlyinuse.Itprovidestheabstractionsthatapplicationsneddtousethenetwork..Withoutthe()layer,thewholeconceptoflayeredprotocolswouldmakelittlesense.
A.traffic B.connection C.lines D.networks正确答案D
