An Ethernet switch is a network device that connects computers, servers, access points, IP cameras, and other equipment within an Ethernet local area network (LAN) and forwards data between them. A switch receives Ethernet frames through one port and forwards them to the port connected to the destination device.
Ethernet switches are used in home and enterprise networks, data centers, telecommunications infrastructure, and industrial systems. Depending on the model, they can have anywhere from a few ports to dozens of high-speed interfaces and support speeds ranging from 100 Mbit/s to 400 Gbit/s and beyond.
How Does an Ethernet Switch Work?
A standard Ethernet switch operates primarily at the data link layer (Layer 2) of the OSI model. It uses the MAC addresses of network devices to determine where traffic should be forwarded.
When an Ethernet frame arrives at a port, the switch examines the source MAC address and stores information about the port through which that address can be reached in its MAC address table. It then checks the destination MAC address. If a corresponding entry already exists in the table, the frame is forwarded only through the appropriate port.
If the destination address is not yet known, the switch performs flooding, forwarding the frame through the other ports in the relevant network segment, except for the port on which the frame was received. After receiving a response, the switch can add the new MAC address to its table.
This approach uses network bandwidth more efficiently than legacy Ethernet hubs, which forwarded incoming traffic to all ports.
Types of Ethernet Switches
One of the main classifications divides Ethernet switches into managed and unmanaged switches:
- Unmanaged switches generally require no initial configuration. Devices are connected to the ports, and the switch automatically handles Ethernet traffic forwarding. They are suitable for relatively simple networks.
- Managed Ethernet switches provide significantly more options for network configuration and control. Depending on the hardware, they may support VLANs, Quality of Service (QoS), link aggregation, Spanning Tree Protocol (STP), traffic monitoring, and other features.
A separate category includes Layer 3 switches, which can perform not only MAC address-based switching but also IP routing between different networks or VLANs.
Ethernet Switch Speeds and Interfaces
The choice of an Ethernet switch depends, among other factors, on the required network bandwidth. Modern switches may support Gigabit Ethernet, 10GbE, 25GbE, 40GbE, 100GbE, 400GbE, and higher speeds.
Connections can use copper Ethernet ports with RJ45 connectors, as well as optical or combined interfaces with SFP, SFP+, SFP28, QSFP, and other transceiver form factors.
In data centers, high-speed Ethernet switches are used to connect servers, storage systems, and network equipment. The performance of such a switch is determined not only by the speed of its individual ports but also by the device’s overall switching capacity.
Additional Features of Ethernet Switches
Some models support Power over Ethernet (PoE), which transmits both electrical power and data over a single Ethernet cable. This makes it possible to connect devices such as IP phones, surveillance cameras, and Wi-Fi access points without a separate power cable.
Managed switches can also use VLANs to logically divide a single physical infrastructure into multiple networks, QoS to prioritize certain types of traffic, and redundancy mechanisms to improve network availability.
Ethernet switches are therefore a fundamental component of wired network infrastructure, from small local networks to the high-performance networks used in modern data centers.