Avoiding WLAN Set-up Headaches (Part I)

By Gerry Blackwell

January 11, 2002

Setting up an effective WLAN in your home or office doesn't have to be difficult but it does require some in-depth planning and analysis. Here are some observations about some potential pitfalls that can be avoided with a bit of leg and brain work. When in doubt, use site survey tools!

The sudden explosion of Wi-Fi equipment on the market and the broad acceptance of the technology by business and home users is mostly a good thing for the industry and for users. But there is a downside.

Vendors, not without justification, have pushed the idea that Wi-Fi networks are extremely easy to set up - and so they are sometimes. But sometimes, a lot of times, they're not.

Too many companies are trying to do their own installs with only the most rudimentary understanding of the equipment and of RF technology. Many as a result screw up. It's too bad. Some of the mistakes they make are eminently avoidable.

At this week's 802.11 Planet conference in San Jose CA, we're convening a panel of grizzled veterans of the fixed wireless wars to discuss "Building & Equipping Wireless Networks That Work." It's essential training for novice WLAN designers.

We thought we'd offer a little conference preview, though, so we called on panelist Jesse Frankel, chief strategy officer and vice president of advanced technology at NeTeam Corp. (www.neteam.com) in Akron OH.

"There are cases," says Frankel, "where you can take the equipment out of the box, turn it on and it works. But there are many others where it's a lot more complex."

Frankel, with over ten years experience in the field, including pioneering work at Austin TX-based Wayport Inc. (www.wayport.com), was a perfect choice for our conference forum.

His company, which refers to itself as "The Wireless Network Architects," has worked with scores of clients across the eastern U.S., setting up office WLANs, campus networks, point-to-point bridges and even a few wide area access networks - mostly using 2.4 GHz spectrum. The company also has offices in Atlanta and southern Florida.

NeTeam is the designer of one of the largest Cisco Aironet installations - if not the largest - in the U.S., at the University of Akron right in the company's home town.

The UA network will eventually provide broadband wireless coverage in every one of the campus's 80-odd buildings and across all the green spaces in between. So far the build-out includes 650 access point, but the NeTeam design calls for double that number.

In the first of this two-part article, Jesse Frankel talks about some of the common mistakes self-installers make and how to solve them. In the second part, we'll take a more step-by-step approach to designing WLANs that work.

Not surprisingly perhaps, Frankel suggests that sometimes self-installers can't solve all the problems they encounter, that it takes an expert - like him. Still, some problems are avoidable as we'll see.

One of the most egregious design blunders Frankel has ever seen was by an unnamed company that set up a point-to-point bridge to link two buildings. The design and install were done during the winter when the trees were bare. You can guess what happened.

"Come spring," Frankel relates, "they discovered there were leaves in the way of the path. Which totally screwed up the reliability of the link. It's obviously something you need to take into account."

The key mistakes made: poor path analysis - or no path analysis at all - and inappropriate selection of antenna.

Most companies recognize that setting up outdoor point-to-point bridges requires specialized expertise and wouldn't think of doing it themselves, he says. But the same is not true of indoor office WLANs.

"The main problem we see in WLAN self-installations is that not a lot of thought is put into throughput analysis during the design phase," Frankel says. "That's really where we start. What are the peak throughputs required and what's the maximum density of users?"

"If they don't have a lot of experience, they're apt to just put one [access point] every 200 feet and turn it on."

Result: users complain about poor performance because the position of access points and selection of antennas does not provide optimum throughput everywhere. Sometimes coverage is so poor there are small "dead zones" in the office with no connectivity at all.

Or slavish adherence to the one-every-200-feet rule means only one access point is installed in a facility such as a computer training room where 30 or more users may try to connect to the net at the same time. The math doesn't work. Total bandwidth divided by number of users equals access speeds slower than dial-up.

Another common mistake is to not plan for changes in the position of cubicles or equipment, Frankel says. Result: a new office configuration changes path characteristics and suddenly users start complaining about a network that once worked fine no longer working at all.

The same thing can happen if you set access points on the tops of filing cabinets or other office furniture where they end up getting moved. It's a common reason for failure in WLANs where NeTeam is called in to put things right.

"The mistakes are, they didn't choose the right antenna and they didn't put the access points in places where they can't be moved," Frankel says.

The importance of picking the right antenna keeps coming up in Frankel's litany of WLAN errors. One of the worst decisions, he says, is selecting access points with fixed antennas - like many home gateway products - and no inputs for external antennas.

"We go in and look and what they have is half a dozen of these things sitting on the tops of file cabinets," Frankel says. "There's not a whole lot you can do with them. You can try and come up with better placement. But there's no way you can do an industrial-grade installation."

Security, not surprisingly, is another major stumbling block. "With most of the self-installed networks we see, they have not properly thought out a security architecture that is really robust. In lots of cases they haven't done anything."

In the odd case, they have gone too far the other way. At one university law school - not UA - the faculty wanted to prevent students from other departments using its network access points so it implemented MAC address filtering, blocking unregistered users.

Frankel calls it "brute force security." It ended up defeating the purpose because it caused all kinds of problems with PC card NICs being stolen and swapped from one student to another.

The law school example is symptomatic of a larger problem in many university implementations where there is no centralized control, Frankel says. Departments decide to invest and set up their network segments however they like. The result is a hodge-podge of a network with poor coverage and performance, Frankel says.

And on and on it goes.

The longer you talk to Jesse Frankel, the more you realize how easy it is to screw up when designing a WLAN. Maybe he's not just promoting his own company's services when he says it takes an expert to do the job right.



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