Ethernet, Fast Ethernet, FDDI and Token Ring often referred to as traditional LAN, and they are sharing media, sharing of bandwidth shared LAN. In order to increase bandwidth, often using a network router division, will be divided into a network of more than one paragraph, each of the networks have different sub-address, different broadcasting domain, to reduce conflicts on the network, increase network bandwidth. Micro-paragraph of the network can not meet the LAN extension and the new high-bandwidth network applications to the demand, it is said that "traditional local area network has come to an end."

In recent years the exchange processes-LAN technology, to address shared by the LAN network inefficient and can not provide adequate network bandwidth and network expansion and a series of difficult issues. It fundamentally changed the structure of shared local area network, to solve the bandwidth bottleneck. At present, the exchange of Ethernet, token ring exchange, the exchange of FDDI and ATM, such as the exchange of local area networks, Ethernet one of the most extensive exchange. LAN exchange has become the mainstream LAN technology.

Switches provide the ability to bridge the existing network and increase bandwidth capabilities.

For the LAN switches on the bridge with similar because they all operate in the data link layer (level 2), M A C-layer, the inspection of all network traffic into the device address. And the bridge still has some similar switch to maintain an address on the table and used the information to decide how to filter and forward LAN flow.

And bridge different, switches using technology to increase the exchange of data input and output media and installation of the total bandwidth. General switch delay small forward, the economy and can be divided into small network of conflict domain, for each workstation to provide higher bandwidth.