Ad-hoc Or Access Point? Network Structures Explained.

What happens to many people is that they're just about to buy some wireless equipment, and then they have a sudden realisation -- they have no idea how their network layout is going to work with a wireless connection. Well, there are a few things you need to think about when you decide how you're going to connect up your computers with all that great new wireless stuff.

Ad-hoc Networks.

Ad-hoc networks are the ones your wireless devices create more-or-less on their own -- they are also known as peer-to-peer networks. In an ad-hoc network, each computer on the network acts as an equal 'peer', with each one sending data to any other. This arrangement is most often used in place of a real LAN, to allow employees in a company, for example, to exchange files. You can create ad-hoc wireless networks between any computers that have wireless equipment -- access to the Internet is not required.

These networks work using something called an 'SSID' (Service Set Identifier). Essentially, this is the network's name, decided on the computer that was the first to connect to the network (yes, a network consisting of just itself). The other computers that connect to the network can then simply connect by finding the network with the name (SSID) they want.

This is powerful. You can put your wireless-enabled laptop next to a friend's, and the two computers can create a little network for themselves on the fly. Thanks to the way wireless networking works, they keep the connection even if you move them around -- the only thing that will force the computers to disconnect from each other is if they go out of range. For many people, this spells the end of messing around with CDs and floppy disks -- they can finally use their laptop just like a briefcase, carrying everything from one place to another.

Arriving somewhere with your laptop and being automatically included in the wireless network also gives you access to shared resources, such as printers. Imagine being able to take your computer to somewhere where there's a printer, press print, collect the document and walk away again. Ad-hoc networking makes this a reality.

Access Points.

An access point, on the other hand, is a way of connecting your ad-hoc wireless network to a real, wired network. Note that this network could just be a LAN, or it could be the entire Internet. There are hardware access points and software ones, with either kind allowing you to connect your wireless device to a wired network. Internet Connecting Sharing, for example, is a software access point to the Internet, while a wireless router is a wired one. If you have wireless access at your office, the chances are it is provided as a wireless access point to the wired network, to let people bring in wireless devices and connect them to the office LAN.

A network that contains an access point is sometimes called an 'infrastructure' network, as opposed to an ad-hoc one. It's worth remembering, though, that part of the infrastructure network still consists of the ad-hoc network between the computers -- they can still communicate just the same as they could before.

If you think about it, you can see that the access point structure allows you to create a series of networks, all interconnected. The Internet, in this scheme, is just another wired network. You can connect your wired network to the Internet, connect your wireless network to an access point to your wired network -- whatever you want.

The string of networks is potentially never-ending, with wired networks being able to break out into wireless ones as often as they need to. This concept is sometimes called lilypad networking, because it lets your computer be like a frog, hopping from lilypad to lilypad. Even though the whole area of the water isn't covered with lilypads, the frog can still get through -- and you can make wireless networks work the same way.