What Is a Network Switch?

A network switch is a technology that allows two or more IT devices such as computers to communicate with each other, forming a communications network. Switches enable devices on the network to share IT resources such as printers, servers, file storage, internet access, and processing. Simple switches connect devices on a single local area network (LAN), while more advanced switches may connect devices from multiple LANs and incorporate data security functions. Switches typically connect to devices via Ethernet cables connected to Ethernet ports on both devices.

IT devices communicate by exchanging packets of data. A switch receives data packets from connected devices and correctly forwards them to other devices connected to the same switch. Switches operate at the Data Link Layer (Layer 2) or the Network Layer (Layer 3) of the Open Systems Interconnection (OSI) model. Switches operating on Layer 2 identify a device by its Media Access Control (MAC) address, a code that’s part of the device’s network interface card (NIC). When a data packet enters the switch, the switch reads the MAC address in the header and sends the packet out through the appropriate port to the right destination. Most switches offer full-duplex functionality, allowing traffic to travel in both directions between a switch and a device at the same time to avoid connectivity issues. Switches operating at Layer 3 forward data based on a destination IP address.

• Increased bandwidth. Switches create dedicated connections between devices and increase the available bandwidth for each device.
• Improved network performance. Switches provide faster data transfer rates, resulting in better network performance.
• Tighter security. Switches can create virtual LANs (VLANs) to isolate network traffic and separate sensitive data, restricting access to approved devices or groups of devices.
• Easy scalability. Network administrators can easily add switches to a network to increase the number of devices that can be connected.
• Power over Ethernet (POE). Many modern switches provide Power over Ethernet technology, which may offer up to 100W of power for devices connected to the network. A POE switch can power network devices like security cameras, sensors, outdoor lighting, and VoIP phones, enabling these devices to avoid a separate power supply.

Routers forward data packets from one network to another, making them an important part of internet connectivity. Switches are used only for interconnecting devices on the same network. Routers operate primarily on Layer 3, while switches operate primarily on Layer 2. Routers may work with both wired and Wi-Fi networks, while switches work only with wired network connections, principally through Ethernet.

A hub is a physical device that operates on Layer 1, while a network switch is traditionally a Layer 2 device. Unlike a switch, a hub cannot keep track of the addresses of computers it transfers data and traffic to. Hubs simply connect all the nodes in a network, while an Ethernet switch connects network devices together and transfers data packets between them.

Unmanaged switches are plug-and-play devices that offer no configuration interface or options. Their value is in increasing the number of ports in a LAN, enabling more local devices to access the unit. The form factor for an unmanaged switch may be desktop or rack-mounted.

A managed switch enables administrators to modify the operation of the switch, making these devices more appropriate for larger networks. Managed switches enable administrators to control how traffic is prioritized and to set up virtual LANs (VLANs) to subdivide a local network into smaller areas.

Smart switches have a more limited set of features than managed switches but can be configured to deliver more control over data transmissions. Enterprise managed switches offer a full set of management features, along with capabilities for manipulating configurations.

Network switches offer varying speeds. Fast Ethernet switches provide speeds up to 100 Mbps, while a gigabit Ethernet unmanaged switch provides transfers up to 1,000 Mbps, or 1 Gbps. 10-gigabit switches can transmit data at 10,000 Mbps.