Subtitles of the Movie

Let's go over a few basics about wireless networking now. Wireless devices use all kinds of different hardware and technologies to connect to both each other and other networks. They can also connect to wired networks. I'll talk a little bit about that later. Now, if you know anything about basic networking, and you probably need to know a little bit about basic networking, uh, before you take this course, but most wireless networking technologies are implemented at the bottom two layers of the OSI mode. We call those the data link and physical layers. Now, what that does for us is provide an abstraction from the other layers in that the transmission media and devices and signaling, things like that are at those two bottom layers. The upper layers aren't aware, for the most part, of how those layers function. So the application layer that has the HTTP protocol, for example, that helps us to surf the web doesn't need to be aware of how those two layers are working. As far as it's concerned, it doesn't care whether it's on a wireless or a wired network. So it kind of abstracts from the rest of those layers. Now, most wireless devices and networks are based on 802.11 standards, IEEE standards that we'll talk about a little bit later in the course. And they provide for connection, authentication and encryption of the traffic on these devices and, of course as we said just a second ago, wireless can use other common protocols at other levels of the OSI model in the TCP-IP layers for example tend to operate and they don't need to be aware of the bottom two layers where wireless works. Now, we're going to go a little bit more into topologies a little but later but for now you need to know that there are usually three forms of topologies. First of all we have what's called ad hoc. Now, this is usually two devices that are just talking to each other. It could be two cell phones, could be two laptops that are gaming, using wireless networking to game. Those are usually peer-to-peer device connections. Now, an infrastructure method basically uses a wireless client to connect to a wireless access point. Now, this wireless access point may connect to a larger network, uh, such as a wired network or it may connect directly to the Internet. Either way, the infrastructure basically is a central point of managing this wireless network. In a slide here we've seen a basic laptop talking to a wireless access point, the little blue box, they're the Linksys boxes, wireless access point. That is a basic example of an infrastructure network. The third type that we'll talk about is a bridge network topology. Now, a bridge topology normally connects two wireless networks together or it can link two wired networks together using a wireless connection. Let me give you a quick example. Suppose that we have a wired network in one building and another wired network in another building and those two networks need to talk. But we may not have the ability to run a wire between those two networks. So what we may do is connect both those wired networks to two wireless access points and have those two wireless access points talk to each other so that it effectively extends those wireless, those wired networks to each other. Here's a quick down and dirty diagram of basically all three of the types of wireless, uh, architectures we've looked at. You see wireless workstations talking to wireless access point, which can also talk to a wired network. They could also talk to each other as well.