802...What's That?

802.What?

802.11a, b, g, h – Agggggggghhhhhh!! Where does it end? To tell the truth, it’s no longer a dot-alphabet soup to me but I can still see it in people’s faces that the idea of wireless networking appeals. Still, if we’ve got to speak about 802.Anything, they’re going to pass on that home networking idea.

Since it can be so overwhelming, a number of industry wags have tried to make life simple by referring to all these wireless standards as WiFi, but that’s not specific enough to be useful when it comes to buying equipment and setting up a home wireless network. I’ve even seen some very poor assumptions made by otherwise well-informed network engineers in their wireless purchasing decision. When they’re done, they are completely puzzled at why the wireless installation they just did with 802.11a equipment requires twice as many Access Points as their old 802.11b did.

Well, for all of you who don’t want to read deeply, don’t know radio or networks or simply want to identify the right equipment to buy for that new wireless network, this article is for you.

Let’s see if we can do it without major mistakes!

A Quick Cut To The Chase

Lest I lose your interest while deciphering all the standards, I’ll be selfless enough to give you a recommendation up front: Get 802.11G network cards and Access Points/Routers for your home. They’ll work with any older 802.11B cards you may already have as well as the faster 802.11G cards. And, whatever you do, use 128 bit WEP!! (more on that later!)

Now We’ve Said Our ABG’s

First, what’s with all the 802.whatever talk?

The specifications for wireless networking and many other computer technologies are defined by the IEEE (Institute of Electrical and Electronics Engineers – http://www.ieee.org) . The original specification for Ethernet networking (the kind which uses a cable) is called 802.3 and was published by the IEEE. Another specification you’re more likely to be familiar with is the Parallel Port on the back of your computer. This used to be the most common way of connecting a printer to a PC and the IEEE specification for that technology was IEEE 1284. One more example of an IEEE standard is 1394 – most of us know this one as FireWire. The number business with IEEE is all about identifying the type of technology and a patent or standard value to describe that technology.

802 is IEEE’s way of describing Ethertypes. The decimal portion of these standards represent variations within that type. The alphabetic classification describes further variations within that sub-type.

For giggles, if you don’t think wireless networking is a hot topic today, take a look at the various patent letters concerning 802.11 technology at http://standards.ieee.org/db/patents/pat802_11.html .

So, if 802 is IEEE’s type for Ether networking, .11 is the subclass of Ethernet transmissions via radio and the a, b, g, h and so on reflect particular variations of frequency, encoding, etc.

So without further ado, here’s a small table of the various 802.11 subtypes.

802.11 Subtypes

There’s an interesting detail in the above table (by the way, only the most common 802.11 variations have been listed in the table). Notice that 802.11A and G deliver the same bandwidth but 802.11A runs at a higher frequency? I’m sure you did and I’m also sure you probably saw that higher frequency and thought, “That’s for me!!”

Bigger Is Not Necessarily Better

Unfortunately, in most cases it won’t be what you want. First, 802.11A is not compatible at all with any other style of 802.11 networking. The way channels are used and the way clients connect to the wireless network un 802.11A is unique from any other system so you won’t be able to let your friends with their 802.11 B or G network cards on your network. Another problem is that for a given amount of power, higher frequencies penetrate standing objects less efficiently than lower frequencies. I know it’s counter-intuitive but consider an example. What is it that you hear from the car next to you at the stop light? Is it the high tones? Or is it that earth moving low bass tone?

High frequencies are highly directional, lower frequencies are omni-directional. This holds true whether we’re considering audio or radio. As a result, employing an 802.11A wireless setup in a location with many walls and internal ceramic or concrete structures results in a wireless network with a severely limited range when compared to the penetration of any of the other standards employing 2.4 GHz transmitters.

This isn’t all bad, though. If you’re conscious of security and want to limit the distance to which people can detect your network and limit the kind of hardware they can use to connect with it, 802.11A is probably a good bet. Just be prepared to use roughly 4 times as many wireless access points to cover the same range as an 802.11B device. That’s a result of something you should have noticed in Physics class (were you paying attention); the Inverse Square Rule. That rule says that to produce twice the rate, you must consume 4 times the energy. Note that 802.11A is twice the rate of an 802.11 G set? Since these devices are limited in how many Watts they may transmit, expect the 802.11A set to cover only ¼ area of an 802.11G system.

Other Things To Consider

WEP, let’s consider them. Them? Yes, there’s another source of confusion in all of this. WEP stands for Wired Equivalent Privacy (you’ll often see the E translated incorrectly as Encryption) and it’s supposed to be a single standard offered with two different strengths. The strengths are commonly referred to as 64 and 128 bit WEP but that’s a misnomer. Due to the initial characters in each form being reserved by the protocol, the ‘bitness’ of these are actually 40 and 104 bit.

The whole idea behind WEP is that every packet transmitted between your computer and the Access Point is encrypted using a WEP key. When you set up the network, you set up the key by entering a string of hexadecimal characters or text of either 5 or 13 characters (depending on whether you choose 64 or 128 bit WEP) and storing it on the Access Point. In order for any computer to participate in the wireless network, it must also have this same key configured as part of its wireless network settings. The worst part of this design is that the algorithm is weak. That problem is compounded by the fact that all the computers and Access Points in the network use the same key instead of exchanging public keys and encrypting with those keys instead. Essentially, then, all packets transmitted with WEP use the same key and have the same characteristics. Even in traditional cryptography, this is the simplest code to break because the more packets you intercept, the easier it is to identify common phrases and decrypt what the cipher in use is.

It is better than nothing, though, and I encourage you to enable it. If you buy one of those devices that won’t let you enter the WEP phrase in normal text characters and you’ve a particular phrase you want to use for your WEP key, I’ve created a little VBScript for the Windows Script Host that will convert your phrase to hexadecimal. You can then enter that hexadecimal value in your wireless settings and your access point with ease. The script can be obtained at http://www.mousetrax.com/pub/MakeWEPKey.zip. Save the ZIP file to your hard drive and expand the contents as MakeWEPKey.vbs then run it from the command line by typing the following line and pressing enter:

Cscript <drive>:\<path>\MakeWEPKey.vbs

Enter your text when prompted and the script will produce the hexadecimal results. It will also produce a text file containing both the text phrase and the hex translation so be careful to print the file, store it away and delete it from your computer!

If VBScript files frighten you, a text version is available for study at http://www.mousetrax.com/pub/MakeWEPKey.txt. Feel free to show it to your local script geek. Said geek should be able to prove it’s a safe script!

WEP is not the only security protocol available these days since it was discovered that WEP isn’t nearly stout enough to beat an informed hacker. That’s when WAP came along and WAPped us in the head. Unfortunately, WAP support is only included in a few devices as of yet and, generally, enabling it is usually geared to a corporate structure with authentication and certificate servers in place to control access to the network.

Simplifying The Results

All you really wanted to know when you started was what to buy, but you knew that wasn’t nearly enough even before you got curious, right? To be fair, then, I’ll boil it all down again:

1. If in doubt, buy everything as Wireless G or 802.11G. That’s your router/Access Point and all your wireless network cards
2. Enable WEP at the 128 bit level
3. If your device only wants hexadecimal values for the WEP key, you’re still in luck. Download the script, feed it a 5 or 13 character text phrase and use the resulting hexadecimal output.
4. Oh yeah! Have fun!

Greg Chapman is a senior systems engineer for Houghton Mifflin, a consultant for MouseTrax Computing Solutions and a partner/lead wireless deployment engineer for Layer1Wireless, a premiere wireless networking service that show businesses how to keep more customers in their establishments, longer, by easily providing their clientele with free wireless Internet access to enjoy as they read, dine or drink.

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