Ethernet network switches route packets between ports at the OSI layer 2, which means that (in Ethernet) the network switches decide where incoming packets are transferred to, based on the NIC's 48-bit address. Upon receipt of a packet, the switch forwards the packet to its destination port. Form factor, protocol, performance, port, and features are all important to consider when selecting network switches.
Important performance specifications to consider when searching for network switches include number of ports, data rate, and memory. Number of ports specifies the total number of ports available on the networking equipment. Data rate is the maximum data transfer speed. Memory is the total memory of the network equipment. Common port configurations for network switches include AUI, BNC, IEEE 1394 (also know as FireWire), GBIC, MIC, RJ-45, SC, serial, ST, ISDN BRI S/T, ISDN BRI U, and USB. Features for network switches include stackable, rack mount, LED indicator, full duplex and VPN. Switches that are stackable conserve space. Rack mount network switches are designed to be mounted into a rack. LED indicators are used to indicate the status of the switch. Full duplex signifies the ability of a device or line to transmit data simultaneously in both directions. A VPN is a connection that has the appearance and many of the advantages of a dedicated link but occurs over a shared network. Using a technique called "tunneling," data packets are transmitted across a public routed network in a private "tunnel" that simulates a point-to-point connection and allows network protocols to traverse incompatible infrastructures.