What Is a Switch?

A network switch is a small device that centralizes communications among several connected devices in one local area network(LAN).

Stand-alone Ethernet switch devices were commonly used on home networks many years before home broadband routers became popular. Modern home routers integrate Ethernet switches directly into the unit as one of their core functions.

High-performance network switches are still widely used in corporate networks and data centers. Network switches are sometimes referred to as switching hubs, bridging hubs or MAC bridges.

Ethernet switches are the most common type, although you'll also find switches optimized for ATM, Fibre Channel, and Token Ring network architectures.

Mainstream Ethernet switches like those inside broadband routers support Gigabit Ethernet speeds per individual link, but high-performance switches like those in data centers usually support 10 Gbps per link.

Different models of network switches support varying numbers of connected devices. Consumer-grade network switches provide either four or eight connections for Ethernet devices, while corporate switches typically support between 32 and 128 connections.

Switches also connect to each other, a daisy-chaining method to add a progressively larger number of devices to a LAN.

Basic network switches like those used in consumer routers require no special configuration beyond plugging in cables and power.

Compared to these unmanaged switches, high-end devices used on enterprise networks support a range of advanced features designed to be controlled by a professional administrator. Popular features of managed switches include SNMP monitoring, link aggregation, and QoS support.

Traditionally managed switches are built to be controlled from Unix-style command line interfaces. A newer category of managed switches called smart switches, targeted at entry-level and midrange enterprise networks,​ support web-based interfaces similar to a home router.

A network switch physically resembles a network hub. Unlike hubs, however, network switches are capable of inspecting incoming messages as they are received and directing them to a specific communications port — a technology called packet switching.

A switch determines the source and destination addresses of each packet and forwards data only to the specific devices, while hubs transmit the packets to every port except the one that received the traffic. It works this way to conserve network bandwidth and generally improve performance compared to hubs.

Switches also resemble network routers. While routers and switches both centralize local device connections, only routers contain support for interfacing to outside networks, either local networks or the internet.

Conventional network switches operate at Layer 2 Data Link Layer of the OSI model. Layer 3 switches that blend the internal hardware logic of switches and routers into a hybrid device also have been deployed on some enterprise networks.

Compared to traditional switches, Layer 3 switches provide better support for virtual LAN configurations.