ComputerNetworksandtheInternet11.1WhatIstheInternet?21.1.1ANuts-and-BoltsDescription21.1.2AServicesDescription51.1.3WhatIsaProtocol?71.2TheNetworkEdge91.2.1AccessNetworks121.2.2PhysicalMedia181.3TheNetworkCore221.3.1PacketSwitching221.3.2CircuitSwitching271.3.3ANetworkofNetwo