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Wireless Networking - 25 Feb 2003

The problems with implementation are real, but the benefits are worth your effort

If I've learned anything in my more than 20 years in IT, it's that no product lives up to its hype. Wireless networking products are no exception. In fact, in terms of proving vendor claims, these products have been worse than other types of products. Every time I write about 802.11 products, my Inbox fills up with email messages complaining that the various 802.11 devices don't live up to the claims on the packaging or expressing concerns about poor product performance.

Nevertheless, good reasons exist for introducing wireless networking into your enterprise. For example, because I can take my notebook computer into meetings and have access to all of my network resources, those meetings are more productive. Having a wireless connection during meetings makes scheduling, information sharing, and printing out documents to a local printer possible.

Fundamentally, however, the problem is this: 802.11 vendors have done a poor job of managing user expectations. The most common complaints I hear are that these products' range and speed don't live up to vendor claims.

Problems with Range
As is apparent to anyone who has used 802.11 products, vendors base range claims on perfect conditions. Sometimes I think that the reported ranges for 802.11a and 802.11b products could only be achieved if the antenna were placed on a tall pole in the middle of an open field. In an office environment, so many factors can interfere with signal propagation that you're unlikely ever to achieve the range claims that the vendor advertises. If you want reliable wireless access throughout your enterprise or even a small LAN, you'll need to use multiple Access Points (APs), even in a single-story building. (For more information about APs, see Jeff Fellinge, "Setting Up and Deploying Multiple APs," December 2002, InstantDoc ID 27092.)

These days, typical office building construction requires metal wall studs and framing, which combined with typical office wiring and fluorescent light fixtures creates a hostile environment for 802.11 networking technologies. I've had problems achieving reliable wireless connectivity from an office that's 25 feet away from an AP because four metal-framed walls stand between that office and the AP. However, I've had no problem with connectivity from an office that's 100 feet away from the same AP but has a direct line of sight (with no intervening walls) from the doorway to the AP.

In that same office building, wireless connectivity problems increased as the office became more heavily populated. When the office space was new, the wireless network was set up early to give connectivity to the first employees who moved into the office before the wiring for the wired network was completed. At that early stage, acceptable wireless connectivity was available throughout the 10,000 square feet on the office floor. However, when the complete staff moved into the space, new walls were built, office cubes with wiring were installed, and because of the resulting physical barriers, wireless connection problems became apparent. To address the problem, we added multiple APs to increase the likelihood that a wireless user anywhere in the office would always be in range of a good-quality connection.

Newly constructed buildings aren't the only places to experience wireless connectivity problems. I've received many email messages from users in 50-year-old New York City skyscrapers who experience so much interference on their wireless networks that they measure their effective range in tens of feet. Some users have gone to the extent of installing APs in every meeting room just to make sure that a wireless connection is available.

Problems with Speed
The second most common complaint I hear is that the speed of wireless networking doesn't live up to its claims. Part of this problem relates to signal quality: Wireless NICs drop to lower transmission speeds (e.g., 2Mbps for 802.11b) if they can't make a connection at their rated speed. More important, for any wireless network to transmit user data at the rated speed is technically impossible. All networking technologies must handle overhead, and wireless networking handles overhead notoriously poorly. Between transport protocol overhead and problems such as the requirement that a wireless network check for older wireless networking technologies operating on the same wavelength, the top speed you can realistically expect from 802.11b (rated at 11Mbps) is about 6Mbps. The speed will be lower for an extended data transfer, such as when copying large files. Rated at 54Mbps, 802.11a will deliver top speeds of approximately 35Mbps.

I also often hear about problems users have switching between wired and wireless networks (i.e., docking and undocking notebooks). Windows XP and Windows 2000 have the capability to determine which network connected to the computer is faster and to use that network to transmit files (XP's new Automatic setting makes the determination in XP), but this switching often performs in a spotty fashion. You can specify which adapter has priority by modifying the adapter interface metric on the Advanced properties tab of the TCP/IP settings dialog box; lower numbers take priority.

Moving Between Office and Home
I receive reader email about another problem: moving between wireless networks, typically between a network at home and the one at the office. In an office environment, wireless networks are typically configured as infrastructure networks, which means the network uses APs to connect to wired network devices. Such business networks are almost always configured as secure networks and make use of Wired Equivalent Privacy (WEP) security standards and encrypt network traffic. The typical home network is configured as an ad hoc network (i.e., for peer wireless communication) with little or no security, and moving between home and office networks isn't simple. You need to reconfigure the wireless NIC for each network, which can be difficult, requires the user to have special privileges, and often results in a wireless connection that's unusable in either environment. In these situations, I suggest separate PC Card wireless NICs for the home and office environments; each NIC can have its own configuration, and the user can simply swap PC Cards depending on location.

Wireless networking is fairly mature, and it's here to stay. But it's not as simple to implement as the vendor community wants to believe. When you add wireless networking into your existing environment, make sure to ensure that your users understand what to expect from wireless networking, and cover all your bases.

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