Cisco CCNA 200-301 – Wireless Networking Fundamentals

1. Introduction

You’ll learn about wireless network fundamentals. WiFi networks adhere to the IEEE 800 and 211 standards. You’re going to learn all about the different standards and also the terminology surrounding them, also about the different radio frequencies and channels. The different types of wireless networks that are available are either ad hoc, which are peer to peer connections, or infrastructure mode, which use access points.

Wireless LAN controllers can also be used as well to give you added scalability and ease of management. You’re going to learn how to configure wireless networks in infrastructure mode with wireless APS and wireless LAN controllers from Cisco. So I’ll walk you through how to do the configuration complete configuration on the wireless LAN controller. You’re also going to see how to configure your switches to support wireless networks as well. Okay, let’s get started.

2. Wireless Network Types

In this lecture you’ll learn about the different types of WiFi networks that are available. WiFi services are defined in the IEEE eight two dot eleven standard and IEEE stands for the Institute of Electrical and Electronics Engineers. In the CCNA exam, the terminology that is used comes straight from the eight two dot eleven standard. So that’s a terminology that I’ll be using throughout this section. So the different types of wireless networks that we have first up is a W Pan. That’s a wireless personal area network and a W pan. The devices are very close together within 10 meters of each other and Bluetooth is often used for reconnectivity here.

WLAN is a wireless local area network that provides access to a campus network. That campus will typically be a wired network and having WiFi also allows you to connect to it wirelessly as well. It is possible that the entire network, like the entire building, your corporate office, everybody is connecting their wirelessly. But more like labor is going to be a wired network there with a WLAN. It allows you to connect to that wired infrastructure without the need for a wire, a cable, yourself. And the devices are within 100 meters of a wireless access point with a W line. We’ll be talking a lot more about wireless access points throughout the rest of this section.

Finally, we have a Wman, which is a wireless metropolitan area network that covers a large area such as a city. And for the CCNA exam, it really focuses on WLAN wireless local area network for wireless access to a corporate campus. Okay, looking at ad hoc networks now. So with ad hoc networks, two or more wireless stations communicate directly with each other. Your first bit of terminology there whenever you’ve got a device communicating on the wireless network, it’s known as a station. So with an ad hoc network, that is a peer to peer network where your wireless stations communicating directly with each other. And that peer to peer network is known as an IBSS, an independent basic service set. So you can see in the example here, I’ve got three laptops.

We’re all communicating directly with each other. The circle on the left is the laptop. On the left, coverage area. You can see the coverage area for this laptop here and then the coverage area for this laptop here. Because we’re all in each other’s coverage area, we’re all able to communicate directly with each other. But it’s probably pretty obvious. You can see there’s going to be a scalability issue with this because what if we add another laptop to the picture?

And now this laptop is in the coverage area of the two other laptops nearest to it, but it’s outside the coverage area of the laptop on the left. So there’s that scalability issue with ad hoc networks. It only really works for a W pan, a wireless personal area network where the devices are all very close to each other. So this is where infrastructure mode comes in which can solve that scalability issue. In infrastructure mode, rather than the devices communicating directly with each other over wireless, they communicate via a wireless access point.

So you can see the two laptops here when they’re communicating with each other or anything else they’re going to be sending frames to the wireless AP and it’s a wireless AP that forwards those frames on. Now, if you look here you’ll notice that the wireless AP has also got its own coverage area. So how does this solve the scalability issue that we had in ad hoc networks? Well, the first reason is that the wireless AP can be connected to the wired network. So this now gives your wireless devices access to that entire wired network and beyond it. And also you can deploy multiple wireless access points so that you get coverage across the entire area that you want. Now, wireless stations work in either ad hoc or infrastructure mode.

They can’t operate in both at the same time. So what if you’re in the corporate office, you’re connected to the wireless LAN but you also want to connect to a wireless monitor as well. But does that mean you can’t do it? Well, there is a solution for this and that is WiFi Direct. WiFi Direct allows devices to be connected to an access point super in infrastructure mode and also be part of a peer to peer wireless network. But I thought I just said that you can’t have infrastructure mode and ad hoc mode working at the same time. Well, that still holds because with WiFi Direct it does not operate in ad hoc IBSS mode. It’s an extension to infrastructure mode so it’s still infrastructure mode. WPS WiFi protected setup enables connection set up by pushing a button so it’s very easy to set up and it’s a WPAN wireless Personal area network because for the peer to peer connection the devices have to be closed together.

The predefined services that are available with WiFi Direct are miracast to a wireless external monitor. DLNA Digital Living Network Alliance allows devices to stream music and videos to each other and they can also direct print. Another couple of things to tell you about wireless bridges is the first one wireless bridges can be used to connect areas which are not reachable via cable to the network. So in the example here you can see over on the left maybe this is our warehouse and it’s not possible to get a wired connection going in there from the main building. But what we could use to get connectivity to the warehouse is we could put a wireless bridge in there and have a wireless connection going over to the main building. So wireless bridge is often used to give connectivity between buildings where a cable is not possible. And the last one is mesh networks.

Mesh networks are becoming very popular in home networks. Now this is another option to spread the coverage area of a wireless one. One AP radio is used to serve clients, and the other radio in the AP connects to the backhaul network. So you can see here, we’ve got our main switch here, it’s connected to an AP. And then we’ve got a backhaul and the 5 GHz radio to another AP and then another bat to another AP. And this could go on as well. So you can see that this can extend the coverage area, giving you a large wireless coverage area and still connect it into your wired network. Okay, that was everything I needed to tell you here. See you in the next lecture for more wireless.

3. Infrastructure Mode and Wireless Access Points

You’ll learn about wireless infrastructure mode and access points. And it really helps to understand how W lines work if you understand the terminology from the 800 and 211 standard. So I’ll be going through the standard terms in this lecture. Wireless access points provide connectivity between wireless stations and between the wireless and wired networks. And when your wireless devices are communicating through a wireless access point, they’re operating in infrastructure mode. Wireless is half duplex, meaning only one device can communicate at a time. So in that regard, your wireless access points operate similarly to hubs. Here’s a picture of a typical wireless access point from Cisco. Your wireless APS can have either internal or external antennas. You can see the one here is internal and they can also be designed for indoor or outdoor use.

Okay, first piece of terminology is BSS, the basic service set. So an access point centralizes access and control over a group of wireless devices. Those devices under wireless settings make up a BSS. You remember from the last lecture when we covered ad hoc mode, it was called an IBSS, an independent basic service set, because in that peer to peer network, the devices were operating independently without an access point. Well, now we do have an access point. So it’s not independent anymore. It’s just a BSS basic service set. Next terminology is DS, the distribution system. So your wireless AP provides connectivity to the wired network for the wireless clients. And it’s a distribution system that connects the wireless access points to the wired network. So in the example here, you can see our AP is connected to the switch here.

That’s where it’s getting connectivity to the wired network. So the switch is known as a distribution system. BSSID is a basic service set Identifier. Devices within the basic service sets are identified by their BSSID and that is based on their Mac address. So you see the example here. Our wireless AP has got Mac address A-B-C so that is used as its BSSID to identify it in the wireless network. BSA is a basic service area and the BSA is a wireless coverage area of an access point. This is also known as a wireless cell. Do you see the example here? We’ve got our AP in the middle. That is its basic service area, its area of coverage. That’s the BSA. SSID is a service set Identifier.

The SSID is a unique Identifier that names the wireless network WLAN. For example, corporate. For sure you’ve seen this before. If you’ve walked into any coffee shop and asked to get onto their wireless network, they will give you the SSID and the password to connect to a single access point can support multiple SSIDs. For example, corporate and guest and different SSIDs can have different security settings and be mapped to different VLANs. So, for example, in our corporate office, we have created a corporate SSID and a guest SSID for users to be able to connect to the corporate WLAN they need to supply a valid username and password. When they do that, they’re mapped to the corporate VLAN and IP subnet and they get connectivity to all of the internal corporate resources, like servers. If a guest walks into the company and they want to get wireless access, they can get that too. They connect to the guest SSID. To do that, they only need to provide a password rather than be a valid user inside the company. But when they connect to the guest SSID, they’re mapped to the guest VLAN and IP subnet, which does not have access to any internal resources.

We just give them Internet access, beacons, wireless access points, broadcast information about their W lands, including the SSID and authentication requirements. With beacon frames, this can be disabled, which can give you a little bit of extra security because people cannot then easily see the SSID. However, it is trivially easy to sniff this information from other traffic in the wireless area and find out that information. ESS is an extended service set. The same SSID can be supported across multiple access points to give a larger coverage area. So you can see in our example here, we’ve got our corporate SSID, we’ve got a wireless AP on the left here and it’s got its coverage area, its BSA. And then we’ve got another wireless AP which has got its coverage area, its BSA. And we can keep adding additional wireless APS in our building until we cover the entire area.

Now, when you do that, you want wireless APS which are neighboring each other to be using different channels so they don’t interfere with each other. I’ll cover that in a lot more detail in a later lecture in this section. And finally, we have got roaming wireless client stations can roam across wireless APS supporting the same W Lans. So in our example here, we’ve got our laptop here, which is currently connected to the first AP. If you’re on that and you’re wondering about the building with your laptop, then your laptop can roam to other APS like that. Okay, that was everything that I needed to cover here. In the next lecture, we’ll talk about wireless LAN controllers, which give us more scalability again.

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