Wireless Network Devices – CompTIA Network+ N10-006 – 2.7

| April 21, 2015


We rely on wireless access points and routers to provide us with mobility at work and at home. In this video, you’ll learn about wireless bridges, wireless routers, roaming, wireless controllers, and more.
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You may have walked through a building or a store and noticed on the ceiling that there are some small devices up there with some antennas attached. And in many cases, those are wireless devices. We generally put wireless devices into two separate categories. A wireless bridge or access point and a wireless router. A wireless bridge, we also call these wireless access points, are there to simply extend an existing Ethernet connection out into a wireless area.

This is something that’s not doing routing. The wireless network is not on a separate subnet, this is a very basic bridge that’s simply extending the Ethernet connection that’s already there. The other kind of device you’ll see is a wireless router. These are devices that are commonly seen in home offices or small offices and you probably even have one at home on your internet connection. A wireless router consists of multiple components all combined in the same device.

In fact, there’s a wireless access point inside of this device. You can connect to the Ethernet ports on the back of this device and they’ll extend themselves out on to the wireless network. But there’s also usually a router inside of this device as well. And that’s the part that gives us that connectivity to the ISP because it provides us with private IP addressing on the inside of our network and routes and does network address translation to the outside of our network.

And when we refer to a wireless router, we’re generally referring to one of these devices that has the routing and the access point functionality all in the same device. Wireless access points allow us to extend our Ethernet networks wherever we might need them. You generally see these on multiple floors of a building. If you have a campus environment, you might have them even outside as part of the campus between buildings. And at very large organizations, you can have hundreds of access points or even thousands of access points around the world.

If you have deployed a number of access points in your building or on your campus, you can then begin to move from place to place and have complete network connectivity the whole time. We call this wireless roaming, where you can start in one place and walk to another place, and at that time you’re moving from access point to access point to access point, but because it is a seamless transition, you have no idea that you’re changing frequencies or changing access points. We’re able to accomplish this by providing the same SSID across all of the access points.

We use the same encryption method and we use the same method for authentication. The access points then are able to simply move from one to the other and hand you off as you’re walking by. This is a common way to set up the access points because the end user doesn’t even have to think about how to connect to the network or move from access point to access point. The entire process is handled automatically.

As we start to deploy more and more access points, it becomes more and more difficult to manage and control all of these different devices. So at that point, you might want to consider using a wireless controller. This is a centralized management console. It’s a single front end that you can use to manage all of those individual access points. So instead of connecting to each access point individually, you simply go to one single console.

These are usually rack-mountable appliances, 1 or 2U in size. And it’s one where you simply slide it into the rack, give it an IP address, and now you’re able to use the functionality of this management console. And now from one central place, you can view all of your access points all at one time. You can view performance information, and if you need to make a configuration change, you make it in one place and push that configuration out to all of your different access points.

Behind the scenes, the mechanism that allows you to have this centralized control is a protocol called LWAPP. That stands for Lightweight Access Point Protocol. This is one where once you’ve made your configuration changes and you want to update all those access points, your management frontend on the wireless controller sends that information using LWAPP. This gives you a way to set your configuration settings, apply security policies, press one button, and then have LWAPP deploy that to all of your different access points.

Another capability that’s enhanced by using a wireless controller is called VLAN pooling. We know that on wired networks we only want to have a certain number of devices on a particular subnet. Once we begin growing larger and larger subnets, we begin having more and more broadcasts, and therefore more and more congestion. On a wireless network, it’s an even greater concern because as someone else is communicating on that network, nobody else can talk. It’s a half duplex communication on a wireless.

So you want to be sure to minimize the size of these subnets. With VLAN pooling, you can have this process automated. So the wireless controller and the wireless access point are configured to only allow a certain number of devices on a single subnet. And if you reach that number, you can then deploy people to a different subnet. Maybe you start load-balancing across the different VLANs.

This is one very easy way to minimize the amount of congestion, the amount of broadcast, and the overall traffic that might be on a single subnet. These wireless controllers usually use some type of criteria to determine what user goes in which the VLAN. Very common criteria is the MAC address or the physical hardware address of the wireless access point.

So it might examine the MAC address, make a determination of how it should separate out all of the different devices by MAC address, and then start placing them into the appropriate VLAN. And by doing this, it’s able to minimize the amount of devices on a single subnet, you’re minimizing how many devices are affected by a broadcast, and keeping your wireless networks running at peak efficiency.

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Category: CompTIA Network+ N10-006

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