Network Switch

What Is a Network Switch?

A network switch is a device that connects computers, printers, servers, and other equipment on the same local network. It receives data and delivers it only to the device that data was addressed to.

Plug a computer into a wired office network, and the port it lands in almost always belongs to a switch. Twenty people can then print invoices, pull files from a shared drive, and hold video calls at the same moment without any of it interfering. A heavy file transfer at one desk stays at that desk instead of slowing everyone else down.

Forwarding depends on MAC addresses. A MAC address is a fixed identifier given to a device's network interface, and no two on one network are alike. The switch reads the destination address written into the arriving data and pushes that data out of the port which reaches the matching device.

Offices, schools, hospitals, factory floors, retail stores, data center racks: switches turn up in all of them. And what plugs into them goes well past laptops and printers. Wireless access points terminate at a switch port. So do IP phones, security cameras, and other network devices that need a wired link.

A switch works inside a network. Connecting that network to the internet is a separate job, and it belongs to a router.

How Does a Network Switch Work?

Learning comes first. Power a switch on and it has no record of what is connected to it.

The first message any device sends changes that. Two details are lifted out of it: the sender's MAC address and the port the message came in through. The switch stores them as a pair. Repeat this a few thousand times and it holds a working map of the network, kept in what is called a MAC address table.

After that, forwarding is quick. Incoming data carries a destination address, the table says which port that address belongs to, and out it goes.

Now and then an address is missing from the table. The switch briefly sends the data out of every port, waits, and whichever port answers gets written in as the entry for next time.

Nobody maintains any of it by hand. Old entries age out on their own, and fresh ones appear the moment someone unplugs a laptop in one room and connects it again down the corridor.

Because traffic only travels where it belongs, collisions become rare and network congestion drops with them. Hubs lost the argument on precisely this point. Business networks stopped buying them years ago.

What Are the Types of Network Switches?

Choosing a switch comes down to the size of the network and how much control whoever runs it actually needs.

1. Unmanaged switches 

An unmanaged switch works out of the box. Nothing to configure, no login screen. Homes and small offices buy them, and so do meeting rooms that need a few more ports.

2. Managed switches 

A managed switch is the opposite. Ports can be shut off, traffic can be watched, security policy can be enforced port by port, and one physical network can be divided into separate virtual networks.

Quality of service comes with it too, which is what stops a video call from queueing behind a scheduled backup. Most medium and large organizations run them.

3. Layer 2 and Layer 3 switches

Layer 2 of the OSI model is where the majority of switches operate, forwarding on MAC addresses and nothing else.

A Layer 3 switch adds basic routing. Because it can read IP addresses, traffic moves between VLANs or between separate networks without every request having to travel out to a router and come back.

4. Power over Ethernet switches

Power over Ethernet switches send electricity down the same cable as the data. Ceilings and walls rarely have a socket nearby, so the camera or IP phone mounted up there draws its power from the switch port.

5. Access, aggregation, and core switches

Bigger networks stack switches in layers. Access switches are nearest the users, taking the laptops, phones, and printers.

Aggregation switches gather what the access layer collects and pass it upward. Core switches form the backbone, carrying high volumes between the aggregation layer, the data center, and the routers that reach outside.

How Is a Network Switch Different From a Router and a Hub?

Hubs, switches, and routers get confused with one another constantly, since all three connect equipment. The jobs are not the same.

Take a hub, the oldest and simplest of the three. Anything arriving on one port is repeated out of every other port, needed or not, so bandwidth is wasted and the network degrades as devices are added. Hubs are effectively obsolete.

A switch is selective. Data goes to one device, picked out by its MAC address, and that is why dozens of conversations run at once without interfering.

A router connects networks instead of devices. It uses IP addresses to move traffic between a company LAN and the internet, or between two office networks in different cities.

Most businesses run both. The router deals with what happens beyond the building, and the switch deals with everything inside it.

Why Are Network Switches Important?

How efficiently a local network uses the capacity it already has is largely down to the switch. Every file opened, every print job, every call between colleagues passes through one.

Performance is the clearest benefit. Data reaches the device that asked for it and no others, so nothing is burdened with traffic addressed elsewhere, and the available network bandwidth gets used properly.

Growth is the quieter benefit. Hiring twenty people means adding ports rather than redesigning the network, and over a few years that difference shows up as real cost savings.

Managed switches give IT teams visibility on top of that. Guest traffic can be kept well away from finance systems. Critical applications can be prioritized when the network is under load. Unusual activity on a single port can be caught before it spreads.

Cloud tools, wireless devices, cameras, connected equipment: offices keep filling up with more of it every year. The switch stays what it has always been, the piece of network infrastructure that everything else plugs into.