What are Network Devices?

You click a link in the school lab and a web page appears. On the way out of the building, your request passed through several different pieces of hardware. Each one did one small job. This chapter is about those boxes.

1The definition

Network devices

Network devices are the pieces of hardware that connect computers into a network, and connect one network to another.

A computer and a cable are not enough on their own. The computer needs a part that can send signals down the cable. The cables need somewhere to meet. And the school’s network needs a way out to the rest of the world. Each of those jobs is done by a device.

2Follow one message

Here is a small school network with every device from your syllabus in it. Press ▶ Play to follow one message from a computer in the lab out to the Internet. Then try the three side trips: a laptop on Wi-Fi, a computer at the end of a very long cable, and a hub in place of the switch.

Every device, in one school network

Press ▶ Play to follow a message out to the Internet, or pick any device.

A school network, from one computer out to the Internet. The violet floor is the school's own network.

Notice that nothing on the way does everything. The card only sends and receives. The switch only passes data between the lab’s cables. The router only deals with the way out. That is why a real network has so many boxes.

3Three groups of devices

The syllabus names nine devices. They are easier to remember in three groups, by the job they do. The chapter takes them in this order.

🖥️ Join a computer to a network

Ethernet card
RJ45 connector
Wi-Fi card

Every computer needs a way onto the network: a card inside it, and a cable plug or a radio.

🔁 Work inside one network

Repeater
Hub
Switch

Carry a signal further, and join many computers' cables together at one box.

🌉 Connect networks together

Router
Gateway
Modem

Move data from one network to another, and out to the Internet over a phone or cable line.

Your home has most of these in one box

The box your internet company gives you at home is usually a modem, a router, a switch and a Wi-Fi access point all built into one case. In a school or an office they are more often separate boxes, which makes each job easier to see.