Network switch

A network switch (also called switching hub, bridging hub, Ethernet switch, and, by the <a href="/facts/IEEE/UddC4pUW">IEEE</a>, MAC bridge) is <a href="/facts/Networking_hardware/ck0rIkXA">networking hardware</a> that connects devices on a <a href="/facts/Computer_network/3w5RM99p">computer network</a> by using <a href="/facts/Packet_switching/olDlDP1R">packet switching</a> to receive and forward data to the destination device.
A network switch is a multiport <a href="/facts/Network_bridge/5nyTQtNW">network bridge</a> that uses <a href="/facts/MAC_address/SVcTfgUH">MAC addresses</a> to forward data at the <a href="/facts/Data_link_layer/K9yPufbt">data link layer</a> (layer 2) of the <a href="/facts/OSI_model/oxN9Xhjz">OSI model</a>. Some switches can also forward data at the <a href="/facts/Network_layer/L2jAtJzQ">network layer</a> (layer 3) by additionally incorporating <a href="/facts/Routing/Ml6MVCaC">routing</a> functionality. Such switches are commonly known as layer-3 switches or <a href="/facts/Multilayer_switch/xYUzC9bY">multilayer switches</a>.
Switches for <a href="/facts/Ethernet/nMfhU8tU">Ethernet</a> are the most common form of network switch. The first MAC Bridge was invented in 1983 by Mark Kempf, an engineer in the Networking Advanced Development group of <a href="/facts/Digital_Equipment_Corporation/ztxs6keA">Digital Equipment Corporation</a>. The first 2 port Bridge product (LANBridge 100) was introduced by that company shortly after. The company subsequently produced multi-port switches for both Ethernet and <a href="/facts/FDDI/nowmb0ue">FDDI</a> such as GigaSwitch. Digital decided to license its MAC Bridge patent in a royalty-free, non-discriminatory basis that allowed IEEE standardization. This permitted a number of other companies to produce multi-port switches, including <a href="/facts/Kalpana%2c_Inc./phQjn1dM">Kalpana</a>. Ethernet was initially a <a href="/facts/Shared_medium/7BPrQ65Q">shared-access medium</a>, but the introduction of the MAC bridge began its transformation into its most-common point-to-point form without a <a href="/facts/Collision_domain/xQ9ll4JE">collision domain</a>. Switches also exist for other types of networks including <a href="/facts/Fibre_Channel/C7C0yreb">Fibre Channel</a>, <a href="/facts/Asynchronous_Transfer_Mode/SzA8ewFL">Asynchronous Transfer Mode</a>, and <a href="/facts/InfiniBand/6CUz47wQ">InfiniBand</a>.
Unlike <a href="/facts/Repeater_hub/t90w5XMX">repeater hubs</a>, which broadcast the same data out of each port and let the devices pick out the data addressed to them, a network switch learns the Ethernet addresses of connected devices and then only forwards data to the port connected to the device to which it is addressed.

Network switch open-in-new

Network switch