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wireles network hacks mods - briere D.

briere D. wireles network hacks mods - Wiley publishing, 2005. - 387 p.
ISBN: 0-7645-9583-0
Download (direct link): wirelesnetworkhacks.pdf
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That would cut costs and improve your ability to enhance your phone over time without doing a “trash can upgrade,” which is what we call upgrading by buying a new cellphone.
Chapter 2
Wireless Network Basics
In This Chapter
^ Dealing with acronyms a-go-go ^ Figuring out the speeds and feeds ^ Staying secure
^ Peering into the standards crystal ball
Лs much as it pains us to tell you this, we really have to get this out of the way: If you’re going to get into wireless networking, you’re going to have to spend at least some time digging into (and figuring out) wireless standards and protocols (which are commonly agreed-upon specifications for how wireless network devices communicate with each other).
Like many other computer and networking-related systems, wireless networks rely on these standards to ensure that disparate pieces and parts work together smoothly. These standards are part of everyone’s daily life — ranging from the standards that make your HDTV work to standards that underlie the Internet itself.
Most of the time, you can safely ignore the standards and just assume that they are there, working in the background for you (when was the last time you had to worry about your long distance provider’s implementation of MGCP in their interoffice switching?). But when it comes to designing, choosing components for, building, and operating a wireless network, standards come to the fore.
lntroducing the 802.11s
Most of the wireless networks we discuss throughout WNH&M For Dummies are based upon a set of standards (called 802.11, explained below) set by a group called the IEEE (or Institute of Electrical and Electronic Engineers — insiders call them the “I triple E”). The IEEE is one of the three main groups in the networking industry that create standards governing how different pieces of networked equipment talk to each other (the other two are the ITU, or
24
Part I: Making Your World Wireless
International Telecommunications Union, and the IETF, or Internet Engineering Task Force).
The IEEE’s 802 LAN/MAN Standards Committee has a large task force of engineers (who don’t work for the IEEE itself, but instead are employees of various technical companies who make software, computer chips, and networking equipment) working on various LAN (local area network) and MAN (metropolitan area network) issues. Each of these issues has its own working groups — including (pay attention to this one!) the 802.11 Working Group, which is focused on wireless LANs.
Within 802.11 (which is the overarching wireless LAN working group) are a number of smaller working groups, each of which is identified by a letter appended to the end of the 802.11 name — for example, 802.11b (we added the italic for emphasis). These working groups are tasked with developing specific enhancements and variants to the basic 802.11 standards.
Why are we bothering to tell you all of this? For several reasons:
^ If you haven’t already, you will hear some of these 802.11 terms as you move forward with your wireless LAN. We guarantee it. You can build a simple wireless LAN without knowing all of this stuff, but as you get more complex, 802.11 something-or-other pops up.
^ 802.11 and wireless networks in general are constantly moving forward. Knowing the 802.11 variants (and we talk not only about current variations, but also future ones) keeps you in the loop.
^ If you know about the IEEE and the 802.11 working group, you can keep track of all this online. Most of the (admittedly very technical) documents of the various 802.11 working groups are available online at the following URL:
http://grouper.ieee.org/groups/802/11/
Beyond the IEEE, another group is “watching over” wireless LAN standards — the Wi-Fi Alliance (discussed later in this chapter in the section titled “Oh my, Wi-Fi”). These folks are responsible for testing and certifying interoperability between vendors — in other words, making sure things actually work in the real world.
Easy as a, b, g
The IEEE has a lot of 802.11 working groups, and therefore a lot of 802.11 something standards. But at the most basic, you absolutely need to know something about only three of them to build and operate your wireless LAN. These are 802.11b, 802.11g, and 802.11a — the three current standards for the physical layer (PHY) of the network.
Chapter 2: Wireless Network Basics
The physical layer is one part (Layer 1) of the seven-layer OSI networking model, which defines everything from the physical media to the applications in a network. If you’re curious, you can learn more about the OSI model at the following URL:
http://en.wikipedia.org/wiki/OSI_model
The physical layer defines how the bits and bytes of data are transferred to and from the physical medium of the network — in this case, the electromagnetic spectrum (or radio waves) of the wireless LAN. The physical layer standard defines all of the important details of how your wireless network takes the data you’re sending across it and converts it to the radio waves that bounce around your home.
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