Ethernet switches are devices that perform multiplexing/demultiplexing of Ethernet LAN connections. They are available in a selection of a number of channels supported including 2, 3, 4, 8 or even 16 channel devices. They can incorporate a variety of functionality and complexity. Switches can provide physical switching of the differential high-speed connections of gigabit Ethernet controllers. They can also be more sophisticated switches, incorporating the MAC and PHY functionality of a controller and interfacing to a processor system bus (PCI) or the media independent interface (MII). Ethernet switches also incorporate configurable LED drivers to power the link, activity and mode LED indicators for the switched Ethernet connections.

Ethernet switches can be simple bus switches with low propagation delay, high bandwidth and can support differential signaling. These typically are passive switches, having low series on resistance' (ron). They have low bit skew between signals in the same package and good isolation between inputs and outputs when not connected. These devices are typically used in applications like notebook docking signal routing and hub and router signal routing.

Ethernet switches can also be Ethernet controllers. These have a standard processor bus interface like PCI or use a variant of the MII. They have packet buffering, forwarding tables, full Ethernet PHY, and MAC functionality and support several physical Ethernet interfaces. Along with the typical controller functionality, they can include more advanced features like port based IEEE 802.1Q VLAN support, spanning tree protocol, and QoS packet prioritization. They can have advanced packet filtering and MAC address filtering. They can also have switch management functionality like port mirroring/monitoring/sniffing, statistics measurement and dynamic reconfiguration.

As Ethernet speeds increase, switching is becoming increasingly challenging because the bandwidths of data that need to be supported are extremely high. Optical interface driving must be incorporated in the system. Such implementations are a combination of devices in a modular form and have interfaces to networks of processors and associated memory to support the bandwidth. The latest processors that support 100G Ethernet have up to 100 high-speed CPUs and special memory cache architectures just to be able to meet the bandwidth requirements!