The 10 Deadly Sins of Wireless

1. Equating mobility and wireless

Subtlety is everything. Even at Network Computing, we tend to lump mobile and wireless into one category, but there are important distinctions between the two.

Mobile applications running on notebooks or PDAs don't always require wireless access: If you don't need information in real time, dial-up access and/or synchronization of data onto mobile devices makes more sense.

On the flip side, wireless isn't always all about mobile access, either. It can instead be used as a substitute for wired infrastructure, like using a wireless bridge to connect two facilities in a metropolitan area rather than running a T1 between them. And even when wireless is used to support a mobile work force, these users are seldom interested in the kind of mobility you get from a cell phone (e.g., network access while driving down the highway). Instead, they typically want "nomadic" access, where they can access the network from their remote locations on the road or in branch offices rather than from the points in between.

If you don't distinguish between mobility and wireless when you install your wireless network, it may not fly. You can't settle for the nomadic approach if you're running an application like wireless voice over IP, for instance, that requires actual mobility.2. Ignoring user demand

Most users gravitate toward wireless. It's like the cordless and cell phone phenomena--these technologies exploded because they freed users from their phone wiring.

With WLANs, it's all about the freedom to carry your notebook computer into a conference room and stay connected (though critics might call that a distraction, especially when you use the laptop to do other work). Surveys by Network Computing and research analysts show that users in organizations with WLAN technology consider wireless valuable to their productivity.

Sure, as an IT admin you can argue that wireless is too costly and comes with baggage like evolving standards and inadequate security. But if you avoid wireless for those reasons, your internal customers will likely conclude that IT doesn't understand their needs. It's tough enough getting user buy-in for critical IT projects; don't make things worse by ignoring users in your wireless plans.

3. Rejecting outside assistanceOtherwise known as pride in the original seven Deadly Sins, this can trip up any organization. IT professionals have always been reluctant to seek outside help in areas where they lack expertise. It makes sense to keep a strategic system project like wireless in-house and to develop internal expertise with it.

But the reality is that many network professionals lack technical experience with analog RF as a physical-layer medium. Unlike conventional copper and fiber-based LANs with structured wiring systems that provide ultra-high physical-layer reliability, WLANs are susceptible to interference and, therefore, are inherently unreliable.

If you lack experience and don't have the luxury of time to learn from your mistakes, seek outside help, even if your primary goal is to hire experts to teach you how to be self-sufficient. If your inexperienced technicians conduct wireless site surveys without the proper training and support, you're wasting your time. An undetected line of interference can ruin your wireless implementation. So don't let your pride get in the way.

4. Miscalculating the ROI

There's no easy formula for calculating the return on investment of wireless systems. In some cases--like when you avoid the cost of wiring by installing a wireless LAN--the cost-benefit analysis is clear. But in most cases, the math is fuzzier.When evaluating ROI, consider both efficiency and effectiveness. Efficiency comes when knowledge workers can work out of the office--in a conference room or cafeteria, for example, or while awaiting their flight at an airport terminal. Turning downtime into productive time can yield substantial benefits: It's possible to cost-justify a WLAN if each worker can put in as little as an extra 15 minutes of work each day using wireless access while away from the office.

Improving business processes with wireless is also part of the ROI equation. Take a transportation and warehousing company that uses wireless to process inventory--the technology lets the enterprise track inventory in real time and fill orders more quickly.

It may be difficult to measure the effectiveness of your WLAN. That's when users can make better and faster decisions with wireless because they can immediately access information. A hospital with wireless can help doctors make more informed decisions about patient medication, for example. While the benefits of better patient care may be real, they aren't easily quantifiable. Likewise, a university with wireless available everywhere on campus can potentially attract better-qualified students and faculty because of its wireless network, though those benefits don't translate into dollars and cents.

It may be possible to cost-justify a WLAN if each worker realizes an extra 15 minutes of productive network connectivity per day.

5. Missing the point with security All organizations face security risks, and you have to tolerate some level of risk to stay in business. Wireless comes with its vulnerabilities, but that doesn't justify banning it because there's a chance a hacker could tap into your network from the parking lot. Instead, consider both the risk and the cost of adding additional layers of security.

Say you decide to install an insecure WLAN outside your firewall, for example, requiring VPN or Web-based authentication for access to internal applications. That may expose your organization to someone who's connecting to your WLAN to surf the Internet for free, but that's probably not a risk that keeps your CFO awake at night. The applications remain safely tucked behind the firewall.

Then again, you could implement multilayer WLAN security, which could double the price tag of your deployment. Depending on your budget, that could kill the wireless project altogether.

6. Waiting too long to go wireless

WLAN technology has become a tremendous retail success, with overall sales in the consumer market now exceeding those in the business market. Once your employees have wireless access at home or at their local Starbucks, they'll want it at the office, too.The failure of IT organizations to respond to this demand on account of resource limitations or security concerns can cause wireless backlash, encouraging workers to set up unsanctioned wireless systems in their departments or offices, which don't have central IT support or security. Also, it can set back your organization: If you wait five years to implement your first WLAN, you'll be hopelessly behind the technology learning curve and ill-equipped to implement secure and reliable systems.

WLAN standards, from security to QoS (Quality of Service), are evolving rapidly. If your plan is to wait for the perfect time to deploy wireless, you may miss the boat entirely. It's often better to at least get started with tactical deployments that yield immediate benefits, like installing wireless in heavily used conference rooms.

7. Confusing data rate with system throughput

When the 802.11b wireless standard was ratified in 1998, it was a breakthrough mainly because it was the first WLAN standard to topple the 10-Mbps barrier set by wired Ethernet LANs. Although bits did in fact move across the medium 11 million times every second, the actual application throughput after accounting for MAC (Media Access Control)-layer overhead was only about 50 percent of the data rate. And that was under ideal test-lab conditions. Ethernet, by comparison, is typically about 90 percent efficient.

Aside from MAC efficiency, interference from external sources (microwave ovens, cordless phones) and other WLANs can also stifle throughput.If you design a wireless LAN based on its data rate rather than its real-world throughput, you're likely to experience serious network congestion and multiple calls to the helpdesk.

8. Over- or underestimating bandwidth requirements

Experienced designers of Ethernet networks long ago learned that the most effective way of dealing with the threat of network congestion is to simply throw bandwidth at the problem.

Think you need 10 Mbps? Install a 100-Mbps LAN. Think you need 100 Mbps? Install Gigabit Ethernet. This strategy has sometimes led to overengineered networks that have average utilizations of 1 percent or less, but it may be the most rational approach when uncertainty about bandwidth needs exist.

For WLANs, you can usually service many more users than you think with a single 802.11b access point, particularly if the most common applications are e-mail and Web access. However, with the growing popularity of high-speed WLAN standards like 802.11a, the development of more sophisticated WLAN infrastructure products and decreasing prices, it's now becoming possible to throw bandwidth at WLANs, too. All you have to do is estimate your aggregate bandwidth requirement, double it and then double it again.So rather than shortchange your bandwidth, know your applications' network requirements up front before you build your wireless LAN. And leave room to expand bandwidth as needed.

9. Installing cheap or insufficient software and hardware

Resist the temptation to deploy SOHO-class WLAN infrastructure products, even for pilot projects. While SOHO products have improved considerably in the past year or so, they still aren't appropriate for the enterprise because most don't support centralized management for hundreds of access points, Power over Ethernet and other necessary functions. Plus, you don't learn much about the limitations of the underlying technology if you spend all your time dealing with products that weren't designed for business environments.

Even if the products work on day one, you can't count on these systems long term. Also, if you buy low-end products at low prices, you set false expectations within management about what the real cost will be for an enterprise-class system.

That doesn't mean you shouldn't shop for the best price. Just don't do your shopping at Best Buy.10. Mismanaging your frequency

Not coordinating your wireless frequencies is like establishing a flat address space on your IP network and letting users pick their own addresses. There will be conflicts, with APs on the same channel interfering with one another like users grabbing for the same IP address.

When wireless LANs are tactically deployed, like in conference rooms, the frequency problem isn't immediately apparent. But as you add more APs, co-channel interference increases, gradually diminishing the overall system performance and slowing access to a crawl. The problem is acute with 2.4-GHz 802.11b and 802.11g systems, where the limitation of three nonoverlapping channels makes it difficult to avoid interference even with the best design.

Experienced vendors and resellers that understand this problem build in the proper physical-layer design up front. And some newer APs dynamically adjust access point channels and power output in response to interference and other factors. But they usually can't adjust the power and channel of client wireless devices.

Dave Molta is a senior technology editor of Network Computing. He is also an assistant professor in the School of Information Studies at Syracuse University and director of the Center for Emerging Network Technologies. Write to him at [email protected].Post a comment or question on this story.

1. Wi-Fi is faster than Ethernet. While the raw data rate of Wi-Fi (11 Mbps) may be faster than the original Ethernet (10 Mbps), Wi-Fi's throughput efficiency is always less.

2. The longer the transmission range, the better. That may be true for some wireless communications, but for wireless LANs, a greater transmission range often results in more users per cell and lower per-user throughput.

3. Wireless networks can be dangerous to your health. Almost all wireless LANs have radio output levels of less than 100 milliwatts (20 dBm). That's about the same output level as the $29 walkie-talkies your parents gave you for your 10th birthday.

4. 802.11g will make 802.11a obsolete. Lots of people think that 802.11g will kill 802.11a because it offers the same data rate as 802.11a (54 Mbps) plus backward compatibility with 802.11b. But overall system capacity for 11a is three to four times that of 11g, and additional bandwidth is likely to be added in the not-too-distant future.

5. Wireless LANs are inherently insecure. Yes, there are security issues with the original 802.11b specification, but there are plenty of ways, including the use of VPNs and security gateways, to make wireless as secure as wired.