Both artificial exchange and program-controlled exchange, all is in order to transmit voice signal, is the need for an exclusive line of circuit switching. And Ethernet is a computer network, it is necessary to transfer the data, so the "packet switching". But whatever the exchange way, the switch between two points provide the characteristics of "exclusive access" will not change. For Ethernet device, is the essential difference between switches and hubs: when sending information to the B, if through the hub, is connected to the hub of all network node receives the message (that is, in the form of broadcast sent), just network adapter at the hardware level will filter out not issued to the native information; And if by switches, unless A notice of switches, radio, or the information sent to B C never received (except in the case for switch control authority to monitor).

At present, the Ethernet switch manufacturers according to the market demand, launched three or even four layer switches. But anyway, its core function is still 2 Ethernet packet exchange, only with a certain ability to deal with even higher packet of IP layer.