Wireless LANs operate at Layer 2 using access points that function similarly to hubs, introducing collision management, network identification, and encryption as core considerations. This content covers CSMA/CA, SSIDs, and the critical need to secure wireless traffic against interception.
Wireless LANs Overview
Wireless is also a layer 2 technology that's commonly used. It is different than Ethernet. It still uses things like MAC addresses, but it operates a little differently.
Wireless LANs use some sort of access point to communicate. Devices talk directly to this access point, and then communication could happen through the access point to these different devices. And so now we have a wireless LAN, where devices are connected all through a LAN using this wireless access point.
Because it has to go through all the same access point, and this access point is limited in the amount of transceivers it has, it acts more as a hub. So for every connection it makes, or when it's talking to a device, other devices can't talk at that same time, and so it acts more as a hub.
What's even worse is sometimes this device right here, as it's communicating to this device, this device might be on the clear on the other end and not hear that this device is communicating. So there can be some issues where two devices are trying to talk at the same time and cause this interruption.
And the further a machine gets out from that area — because there's a very limited range that wireless has — the further this device goes out, the more problems it causes with the other device. So if this device is talking at maybe 1 megabit per second, even if this machine had a 300 megabit per second connection to this wireless access point, it would have to stop and wait for this device before it could communicate, because this device is talking at 1 megabit per second.
So wireless is not always the ideal way to set up, but it sure is convenient. It allows us to have just a single access point and then be able to, without connecting into anything, use our equipment anywhere we go within our buildings. And so wireless access is really commonly used. It has some drawbacks.
Now, as we mentioned, this acts as a hub, so multiple devices could talk at the same time. So what do they use? They use carrier sense multiple access. There are multiple devices accessing this, and it's going to sense to see if anybody else is talking. And then what it's going to do is announce that I am going to talk before it tries to communicate. So it will send out a message before it tries to communicate, letting others know that it's going to talk, and then provided that there's no collision with that, then it will talk. So all the communication can happen with these different devices, while trying to limit the amount of collisions that happen.
Of course, there's still going to be collisions. If there is a collision, there's going to be some sort of backoff algorithm that happens between the two devices that had the collision. They'll both wait a random amount of time, and one will try to start communicating before another because it waits for a random amount of time to communicate. So wireless uses CSMA/CA to facilitate that communication.
An access point will have some sort of SSID, or service set identifier, or an access point could actually have multiple SSIDs. What it is is something that gets broadcasted out that says I'm available and this is the name. So it's essentially the name of the wireless connection. So this could get broadcasted out that this is — we'll just call this AP access.
And then when you get onto your device and you look or scan for what networks are out there, then it will come up with the name of a network. Well, that name of that network is the SSID, or service set identifier.
Now, one of the problems with wireless access points and wireless LANs is that everything gets broadcasted out, so everybody can see everybody's traffic. There isn't really a way you can put something in a direction. You can put signal in a direction the best you can, but anybody that's in that vicinity will be able to read that data and take a look at that data. So the reason for that is, since it's being broadcasted out all around the device and not just in a single direction, you need to somehow implement some sort of security.
So more so than any other communication, you need to have your wireless access point secure, and you need to take your wireless networks and make sure that they are encrypted. So there are lots of different ways to implement this security, but the key to this is you need to encrypt that information that's going from your clients to your access point. Otherwise, anybody will be able to see that traffic, and if there's some sort of sensitive information that's going across those lines, then any of those devices are going to be able to see that traffic and be able to take a look and see what's happening. Especially if usernames or passwords are going across in clear text, that could be a real problem there. So yeah, encrypt your wireless LAN traffic.
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