Corporate Wi-Fi Integration, Part 3 - Page 2

By Mike Houghton

September 29, 2004

Continued from Page 1.

The Security Issue

VPN tunneling and other security measures borrowed from wired networks are being widely used for now. IEEE ratified the 802.11i security standard for wireless LANs in June. What does this mean for us? Read this article where Eric Griffith from Wi-Fi Planet explains the details.

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 with zero interference.

However, in an office environment, so many factors can interfere with signal propagation that you're unlikely to ever achieve the range claims that the vendor advertises. To overcome this issue your WLAN should use multiple Access Points (APs) running at a lower power output versus only a few AP's running at maximum output. More AP's will provide higher capacity and redundancy in a given area by segmenting users over several points.

Problems with Speed

Another common complaint is that the speed of wireless networking doesn't live up the claims made by vendors. 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. All networking technologies must handle overhead and Wi-Fi is notorious for its poor performance in this regard.

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 is even lower for extended data transfer, such as when copying large files. Rated at 54Mbps, 802.11a will deliver top speeds of approximately 35Mbps. This rate is somewhat further diminished when using encryption software for security such as Funk.

Switching between Wired and Wireless Networks

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). However this technique of switching is often glitchy.

And finally, as if you didn't have enough to contend with...

Moving Between Office and Home

In an office environment, wireless networks are typically configured as infrastructure networks, which means the network uses APs to connect to wired network devices on the LAN/WAN. They are almost always configured as secure networks and make use of at least one of the several different encryption protocols available.

The typical home network is configured as an ad hoc network (i.e., for peer wireless communication) with little to no security, and moving between home and office networks is not always as seamless as the typical user would like it to be.

I've found that the simplest way to overcome this issue is to just break down and purchase a second wireless NIC for the home and keep the original for the office. Under this scheme, each wireless NIC would have its own configuration and the user can simply swap PC Cards depending on their location. If the machine has an embedded WLAN NIC, such as a Centrino notebook, then you can simply disable it when using the PC Card WLAN NIC.

Fundamentally the problem is this: Vendors have done a poor job of managing user expectations. The most common complaints I hear are that most products' advertised range and speed do not live up to the vendor claims. So hopefully this information will help you better prepare for the impending disappointments.

Even at this stage wireless networking is fairly mature, and it's here to stay. But it's not as simple to implement and use as most wireless vendors would lead you to believe. When you add wireless networking into your existing environment you must ensure that your users understand what to realistically expect and cover all your bases. End user and tech support training is also an essential factor to consider when implementing an enterprise-wide, integrated Wi-Fi solution.

Page 3: Top Wi-Fi Vendors

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