Among network designers and administrators, wired Ethernet is a known quantity. Plenty is known about how to build good twisted-pair network infrastructures, how to keep them secure, and how to monitor their excess capacity. Not so for the wireless Ethernet networks (built around the IEEE 802.11x standards)–these hold much more mystery for even experienced network designers. 802.11 Wireless Networks: The Definitive Guide aims to codify the body of knowledge needed to design and maintain wireless local area networks (LANs). The authors succeed admirably in this, covering what installation and administration teams need to know and digging into information of use to driver writers and others working at lower levels.

The only significant detail that’s been excluded has to do with security–a notorious weak point of 802.11x LANs. The authors cover the feeble but widely used Wired Equivalent Privacy (WEP) authentication protocol in detail and devote another whole chapter to 802.1x, which is an emerging authentication scheme based on Extensible Authentication Protocol (EAP). The author has considerable skill in communicating information graphically and does a great job of using graphs to show how communications frequencies shift over time and how conversations among access points and network nodes progress over time. This is indeed an authoritative document. –David Wall

Topics covered: How IEEE 802.11a and 802.11b wireless networks (also known as WiFi networks) work, and how to configure your own. The framing specification is covered well, as are authentication protocols and (in detail) the physical phenomena that affect IEEE 802.11x radio transmissions. There’s advice on how to design a wireless network topology, and how to go about network traffic analysis and performance improvement.

Book Description
As a network administrator, architect, or security professional, you need to understand the capabilities, limitations, and risks associated with integrating wireless LAN technology into your current infrastructure. 802.11 Wireless Networks: The Definitive Guide provides all the information necessary to analyze and deploy wireless networks with confidence.

Over the past five years, the world has become increasingly mobile. Traditional ways of networking have altered to accommodate new lifestyles and ways of working. Wireless networks offer several advantages over fixed (or wired) networks, with mobility, flexibility, ease and speed of deployment, and low-cost at the top of the list. Large productivity gains are possible when developers, students, and professionals are able to access data on the move. Ad-hoc meetings in the lunch room, library, or across the street in the café allow you to develop ideas collaboratively and act on them right away. Wireless networks are typically very flexible, which can translate into rapid deployment. Once the infrastructure is in place, adding new users is just a matter of authorization.

After a general introduction to wireless networks, this practical book moves quickly into the gory details of the 802.11 standard. If you ever need to debug a wireless network that isn’t working properly, you’d better understand this material. 802.11 MAC (Media Access Control), detailed 802.11 framing, WEP (Wired Equivalent Privacy protocol), 802.1x, management operations, and the PCF (point coordination function) are all covered in detail. Author Matthew Gast also supplies impressive detail on the physical layers.

As for getting a wireless network up and running… Gast offers clear, no-nonsense guide for using 802.11 on Windows and Linux, using and selecting access points, making deployment considerations, and seeing to 802.11 network monitoring and performance tuning. In the final section of the book, he summarizes the standardization work pending in the 802.11 working group.

If you’re looking for one book that provides a full spectrum view of 802.11, from the minute details of the specification, to deployment, monitoring, and troubleshooting, 802.11 Wireless Networks: The Definitive Guide is worth its weight in gold.

Book Info
Practical guide providing all the information necessary to analyze and deploy wireless networks. Softcover.

From the Publisher
As a network administrator, architect, or security professional, you need to understand the capabilities, limitations, and risks associated with integrating wireless LAN technology into your current infrastructure. This practical guide provides all the information necessary to analyze and deploy wireless networks with confidence. It’s the only source that offers a full spectrum view of 802.11, from the minute details of the specification, to deployment, monitoring, and troubleshooting.

About the Author
Matthew S. Gast is a former aspiring research physicist who found computer networking too addictive for his own good. After spending his youth on the Great Plains, his interests in routing, security, and cryptography pulled him towards Silicon Valley to participate in scaling the mountainous network engineering challenge called the Internet.

In addition to his technology interests, Matthew is a voracious reader on science and economics and a lifelong supporter of the scientific method. He is also a registered patent agent before the United States Patent and Trademark Office.

Excerpt
Chapter 15 - 802.11 Network Deployment

Deploying a wireless LAN is a considerable undertaking. Significant planning is required before you can even touch the hardware. Deploying a wireless network is not simply a matter of identifying user locations and connecting them to the backbone. Wireless LANs provide mobility through roaming capabilities, but this feature comes with a price. Wireless LANs are much more susceptible to eavesdropping and unauthorized access. Working to mitigate the security problems while offering high levels of service makes large wireless LAN deployments topologically more complex, especially because solving security problems means that a great deal of integration work may be required to get all the different pieces of the solution working in concert.

Wireless networks require far more deployment planning because of the nature of the radio link. Every building has its own personality with respect to radio transmissions, and unexpected interference can pop up nearly everywhere because of microwave ovens, electrical conduits, or severe multipath interference. As a result, each wireless LAN deployment is unique in many respects, and careful planning and a meticulous site survey are required before removing any equipment from the box.

Beyond considerations due to the physical environment, wireless networks often extend an existing wired infrastructure. The wired infrastructure may be quite complex to begin with, especially if it spans several buildings in a campus setting. Wireless networks depend on having a solid, stable, well-designed wired network in place. If the existing network is not stable, chances are the wireless extension is doomed to instability as well.

This chapter is about deployment considerations for wireless LANs, written from a technical perspective. How do the features of wireless LANs influence network topology? Besides the 802.11 equipment, what do you need to deploy a network? How should the logical network be constructed for maximum mobility? What do you need to look for in a site survey to make a deployment successful?

The Topology Archetype
Figure 15-1 shows how many wireless LAN deployments evolve. This figure serves as the road map for this chapter. The guiding principle of Figure 15-1 is that mobility must be limited to the link layer, because network-layer mobility is not generally available on IP networks. The other design decisions help augment the access control of the wireless device and lower management overhead by taking advantage of existing services, each of which will be considered in turn.

Some deployments may look like multiple instances of Figure 15-1. The topology shown in the figure provides seamless mobility between the access points connected to the access point backbone network. In very large deployments, such as a campus-wide deployment across a large number of buildings, it may be desirable to limit the coverage areas in which seamless roaming is provided. One common strategy is to provide seamless mobility within individual buildings, but not provide roaming between buildings. Each building would have a wireless LAN that looked something like Figure 15-1, and all the access point backbone networks would ultimately connect to a campus backbone.

Roaming and Mobility
In Figure 15-1, the network linking all the access points, which I call the access point backbone, is a single IP subnet. To allow users to roam between access points, the network should be a single IP subnet, even if it spans multiple locations, because IP does not generally allow for network-layer mobility. To understand this design restriction, it is important first to appreciate the difference between true mobility and mere portability.[1]

Portability certainly results in a net productivity gain because users can access information resources wherever it is convenient to do so. At the core, however, portability removes only the physical barriers to connectivity. It is easy to carry a laptop between several locations, so people do. But portability does not change the ritual of connecting to networks at each new location. It is still necessary to physically connect to the network and reestablish network connections, and network connections cannot be used while the device is being moved.

Mobility, on the other hand, is a far more powerful concept: it removes further barriers, most of which are based on the logical network architecture. Network connections stay active even while the device is in motion. This is critical for tasks requiring persistent, long-lived connections, which may be found in database applications. Support personnel frequently access a tracking database that logs questions, problems, and resolutions. The same argument can be made for a number of tracking applications in a health care setting. Accessing the database through a wireless network can boost productivity because it allows people to add small amounts of information from different locations without needing to reconnect to the database each time. Inventory applications are another example and one of the reasons why retail and logistics are two of the markets that have been quicker to adopt 802.11. When taking inventory, it makes far more sense to count boxes or products where they sit and relay data over a wireless network than to record data on paper and collate the data at the end of the process.

Traditional wired Ethernet connections provide portability. I can take my laptop computer anywhere on the campus at work and plug in. (If I’m willing to tolerate slow speeds, I can even make a phone call and access my corporate network from anywhere in the world.) Each time I access the network, though, I’m starting from scratch. I have to reestablish connections, even if I only moved a few feet. What I’d really like is to walk into the conference room and connect to the corporate network without doing anything.

Download: http://tinyurl.com/gegrw

ShareThis