Why You Ned to Set Up Your Network

By Mark L. Chambers from MacBook All-in-One For Dummies, 2nd Edition

A network is a combination of hardware, cables, and software that allows computers, printers, and other devices to talk to each other. To have a wired network, you need the right hardware and software — and all the hardware and software that you need probably came with your MacBook. (Except for those pesky cables, of course, and a USB-to-Ethernet adapter if you have a MacBook Air.)

You’ll discover everything that’s required to set up your wired network so that you can pick up any additional parts you need. Any good-sized computer store (either the brick-and-mortar or online variety) has everything that you need to get up and running.

You need the right hardware and software to make your wired network sing.

Network interface card (NIC)

A network interface card, or NIC, is a hardware device that your computer uses to talk to the rest of the network. The NIC connects to the network cabling, and it speaks the language of electronics, sending data around the network.

Nowadays, most networks use the Ethernet networking protocol, and most NICs are Ethernet compatible. All MacBooks have some type of Ethernet NIC hardware built right onto the Mac’s main system board. (Note, however, that the MacBook Air offers only wireless hardware built in; you can add a wired Ethernet port to the MacBook Air using an external USB adapter.)

Switch

So you have an assortment of devices in your home or small office that you’ve decided to network. How do you make them all interconnect? Although you could connect just two computers by using nothing more than a single Ethernet cable, you need fancier hardware to connect more than two computers: namely, a switch.

The switch is used to connect everything, so it’s the focal point of the network. Without a switch, you don’t have a network.

A switch is really just a small box that has a bunch of Ethernet ports on it. A port is actually like an Ethernet NIC on your computer, but a switch has lots of them. Inside, all those Ethernet ports are arranged so that the talking (sending) wires from each port connect to the listening (receiving) wires on all other ports. Therefore, when one computer talks, all others listen.

Setting up a switch (and therefore giving birth to your network, which sounds more painful than it is) is usually no more difficult than connecting a power cable to the device and then plugging in your computers with their own Ethernet cables.

You’ll see various lights on the box — usually a power light indicating that the switch is powered on and operational. You’ll also see lights that correspond to each port on the switch; these lights tell you what’s going on in the box. For instance, you normally see the following types of lights:

Link light: Each port on a switch should have a link light. Link lights simply tell you which ports have something alive connected to a given port — that is, a device is connected and powered on.
Speed light: Each port on the switch should have a speed light, which tells you the speed of the device at the other end. Some switches have different lights for different speeds, and some use a single light and make it different colors for different speeds.
Activity light: When one computer speaks, they all hear it. Typically, an entire switch has only one activity light for the entire network, indicating that someone is speaking. With heavy traffic, the light can appear solid.

When an Ethernet switch receives a frame — that’s the name for a standard unit, or packet, of network data — it reads the label on the frame to see the return address of the computer that sent the frame. In a short amount of time (after being turned on and watching the data move around), a switch figures out which computer is located on which port.

Then, whenever data comes into the switch, it looks at the header (some information on the front of all frames, much like a mailing label on a package that you send) and sees which computer should receive the frame. The switch then sends the frame out the port for that computer only.

This is A Good Thing. Instead of forcing all computers on the network to listen while your MacBook speaks (as antique network hubs did) — known as half-duplex — a switch sends the data directly to the only computer that needs to hear it.

Cables

Cables are used to connect the Ethernet port on each computer to the switch, the central hardware of the network. With a little experience, you’ll be a cable-wielding superhero with hundreds of feet of cable draped across every piece of furniture in your place for your first LAN party.

Here’s the scoop on what kind of cables to use. Technically, you can run 100 Mbps Ethernet over Cat-5 cable (like a super-version of the wire that you use for your telephones).

Although you can do 10/100 Mbps Ethernet over Cat-5 cable, any new cables that you buy should be Cat5-E or Cat-6 because these types of cables are specifically meant for use with 1000 Mbps (or Gigabit) Ethernet.

Be sure to buy straight-through Cat-5E/Cat-6 cables (also called patch cables) and not crossover cables, which are used only in certain circumstances. Crossover cables are mainly used to connect two computers directly (to form a tiny, two-computer network), connect a cable/DSL modem directly to a computer, or connect multiple switches.