Switches in Networking

What is a Switch?

A network switch is a device that connects multiple devices within a local area network (LAN) and uses MAC addresses to forward data only to the intended recipient. Unlike hubs, switches are intelligent—they inspect incoming data packets and determine their destination based on the MAC address table. This improves speed and reduces collisions in the network.

Layer 2 vs Layer 3 Switches

Layer 2 switches operate at the data link layer of the OSI model. They deal with MAC addresses and are commonly used in LANs for forwarding data within the same network.

Layer 3 switches also perform routing functions by operating at the network layer. They can handle IP routing between different VLANs or subnets, combining the speed of switching with the routing intelligence of routers.

Switch vs Hub: What’s the Difference?

A hub is a basic device that broadcasts data to all devices in a network regardless of the recipient.

A switch, on the other hand, sends data only to the intended device using MAC address information. This makes switches more efficient, secure, and faster than hubs. Hubs are largely obsolete today.

MAC Address Table and Switching

Switches maintain a MAC address table (also called a CAM table) to keep track of which devices (identified by MAC addresses) are connected to which ports. When a frame arrives at the switch, it looks up the destination MAC in the table and forwards the data through the corresponding port. If it’s unknown, the switch floods the frame to all ports temporarily.

Managed vs Unmanaged Switches

Unmanaged switches are plug-and-play. They’re typically used in home networks and offer no configuration options.

Managed switches offer advanced features such as VLAN configuration, port mirroring, SNMP monitoring, QoS settings, and network diagnostics. These are used in enterprise and data center environments where control and scalability are critical.

VLANs and Switch Configuration

Virtual LANs (VLANs) allow network segmentation using switches. By configuring VLANs on a managed switch, different devices can be grouped logically instead of physically, even if they're on the same switch. VLANs enhance network security and performance by reducing broadcast traffic and isolating departments or services.

Use Cases: Home, Enterprise, and Data Center

Home Networks: Unmanaged switches connect devices like PCs, smart TVs, and printers.

Enterprise Networks: Managed switches support VLANs, redundancy, and network monitoring.

Data Centers: High-performance Layer 3 switches with high port densities and fiber connections are used for fast and efficient traffic handling between servers and storage.