Look at real-world issues that can take down a wireless network, with a special focus on wireless devices.
- You can't be too rich, too thin, or have too many wireless scenarios. So let's just keep having even more fun with more wireless scenarios. Now in this episode, I'm going to break it down into two big groups of wireless scenario issues. Let's start off with a classic problem, the slow wireless network. Nothing is going to get you more popular as an IT support person, than having a network that's running slow.
So when we have slow wireless networks we can zero in mainly on one big thing and that's going to be over capacity. Over capacity simply means you don't have enough wireless access points on your network to be able to handle whatever the needs are for your particular network. You really shouldn't be doing this in the first place. One of the problems that over capacity comes from, is that you don't have good placement of wireless access points.
But the other big issue that comes in with over capacity, is you've just got too many people on the network. In these types of situations you might want to consider spending up extra SSIDs, you might want to consider upgrading to higher speed wireless networks. Things like 802 11AC and 802 11AT now are incredibly fast. And obviously just switching out to a new WAP can make your capacity grow tremendously. But there's one other issue that does come up and this is probably the most frustrating issue that I run into with wireless networks.
And it's something called jitter. Now I've got a WAP sitting here and this WAP's doing a great job. Whenever you are sending data from a WAP to a client, you're having frames bounce around all over the place. Some of the frames are coming straight in. Here I'll make a red box, that's gonna be my client just for this one. Some of them are coming straight in, some are reflecting off walls, some are being refracted through a one raw, half absorbed here, refracted back.
It can be a real mess. The bottom line is that, the beauty of 802 11 is that because of using technologies like OFDM it takes a lot of different paths to get a lot of different frames to the place where it needs to be. That's not a problem when you're trying to download a web page. That's not a problem when you're copying a Microsoft Word document. But this jitter, which is what you're seeing, is these frames are showing up way out of order, is a huge problem for things that are more real time.
For example, if you're watching a video, or if you have a voice over IP phone call, and it manifests as chops, stops, break-ups, and that kind of stuff, that just drives us absolutely bonkers. And jitter is a huge, huge problem. A lot of times you'll have a perfectly functional wireless access point that works great for years, and a lot of time jitter manifests as one of the problems of over capacity.
Cause if you have jitter normally, but you only have one or two clients, they can kinda get around the problem. The downside to jitters is that there is no simple fix. The big issue that you usually do, is you'd need to increase capacity dramatically. You can sometimes play with antenna placement. Look for things that cause tremendous amounts of reflectivity, and try to get around it. For the exam, the big thing they're gonna be lookin' for, more than anything else is that if you're exposed to jitter you're gonna have to spend some money and get your capacity up.
Okay, now that's a couple of types of issues that we're gonna see when we run into with slow wireless networks. But it doesn't just really stop there. In fact another big issue we run into has to do with the antennas. And that boils down to, what I'm just gonna call antenna problems. The two big antenna problems you're gonna run into more than anything else, are going to be incorrect antenna types and incorrect antenna placement. Incorrect antenna types.
I don't run into that very much. Mainly because I take the time and when I'm setting up a wireless network, I do a proper site survey, I do a floor plan, I check my heat maps, I look at my capacity, and when everything's set up I'm in good shape. So when I hear about people saying they have the incorrect antenna type I usually wanna slap 'em in the head and go, "Didn't you organize your self from "the beginning to do it right?" An incorrect antenna type situation, at least for the exam, is gonna be pretty straightforward.
Somebody's gonna be tryin' to plop a highly directional antenna in a place you need a dipole. Or somebody's gonna be throwin' in a patch where obviously a directional antenna comes into play. The reality is, is that good networks don't have bad antenna types. All right, so the other one though is antenna placement. Antenna placement is usually going to be physically with the wireless access point itself. In fact, with many wireless access points, it's built into the WAP and you can't do anything about it.
However, there are situations where you can do some interesting things. For example, for a lot of different types of wireless access points, you can screw in an external antenna. So let's just say you're cheap, I am, and you want to put a Yagi antenna on a regular old wireless access point. You can go to the store and buy one, they got plenty of 'em on Amazon.com. So you buy this Yagi antenna, so you get a big 30 DVI Yagi antenna, and you unscrew one of your old die poles off of your WAP and you screw that back in.
So you've got this amazing amount of gain and that's great, and maybe you wanna leave the wireless access point inside, you're drillin' a hole through the wall, you put some silicon rubber sealant in there and now you've got your own external connection to your boathouse or whatever it might be. There's a huge problem. And a problem that, people make this mistake over and over again when they start playing with their antennas. And what they'll do, is they will buy an antenna with an extremely long cable. Any amount of cable that runs from your radio device to your antenna eats your gain apart.
So when you're buying these types of things you need to be considering the amount of gain lost from very very long cables. These antenna cables will have this clearly marked, it's not that big of a deal but people forget about that. And all of a sudden they put in a 30 gain Yagi antenna and they have lost 45 DBI on the cable itself. It happens all the time. So be thinking about these types of things when you're dealing with antenna placement.
Antennas usually are placed with the actual WAP itself and also sometimes you're gonna run into trouble when you have these really long wires. There's one other little issue that just drives me bonkers. And you know what, let's head over to the whiteboard. I'm gonna show you guys this one. So, it's really common to still see a lot of wireless access points out there. And I'm just gonna draw a pretty picture, and it's gonna have, I literally almost did it in drawing. It's gonna have at least two, maybe more antennas.
We've all seen this type of setup. If we know what our radiation pattern is, we know that these are dipoles. And it should be shooting this way, right? But what if you have a second floor? So you'll see people they'll try to do clever thing like this. Here, let me take that out and you'll see this. If you invite me to your house and I see a wireless access point that's set up like this, think about what the dipole radiation pattern looks like.
What you're doing is you're creating this type of stuff. And what makes it worse, on most of these, one of these is a send and one of these is a receive. This is a guaranteed horrible form of antenna placement that I see all over the place. And yeah, If I show up at your house and I see it like that, I'm gonna be asking for a stepladder and I'm gonna fix it. Don't do this to your dipoles.
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- Implementing wireless security
- Threats to your wireless network
- Wi-Fi Protected Setup
- Installing a wireless network
- Cloud ownership and implementation
- Creating a virtual machine
- PaaS, SaaS, and IaaS
- Mobile networking
- Deploying mobile devices