To accommodate a growing mobile workforce, more companies are installing wireless LANs (WLANs). While organizations initially deployed wireless on a trial basis or to meet the needs of just a few users, now they are making it a standard part of their IT infrastructure.
The Harvard Medical School (HMS) and the Beth Israel Deaconess Medical Center in Boston, Mass., for example, have been using wireless for several years. They are now in the middle of a six month deployment which will expand its use to cover four different types of applications: transmission of secure medical data; web access for patients and guests; Voice over IP; and Radio Frequency Identification (RFID) to track the location of equipment.
“Wireless is now a mature technology and it has become an enterprise service for us,” said Dr. John D. Halamka, CIO for the HMS and Beth Israel.
Plan for Growth
According to people like Halamka who have many years of experience under their collective belts, there are three important lessons to learn in coping with a mobile workforce.
The first is to plan for growth. Although you may initially deploy wireless technology on a trial basis or for a specific function such as accommodating field sales reps, growth must be taken into account at the earliest stages.
“Make sure whatever you put in is scalable,” advises Mike Noe, IT Director for Stanford Law School. “It’s like eating peanuts: once you start, you always want more.”
Stanford already provides full, campus-wide, 802.11b wireless service for its students, faculty and staff. Noe’s next project is to make it easier to rapidly accommodate large numbers of visitors.
“We host dozens of events annually and need a seamless way to add them to the network en masse, and keep them from getting anything other than Internet connectivity,” he said.
Expansion isn’t limited to adding more users. The mobile hordes are also clamoring for greater functionality.
Halamka’s current wireless project, for example, includes replacing over 200 of the hospital’s 802.11b wireless access points with higher-speed 802.11g devices. He said they need the addition bandwidth for video conferencing so they can bring the translation services right to the patient, without having to bring the translator there.
Finding the Site
The next wireless lesson is that the access points need to be carefully placed and tuned in order to obtain optimum accessibility and throughput. This is not just a paper-based exercise. You have to physically survey an area and see how the waves reflect and propagate around a space, as well as what materials are blocking signals.
Piping in walls, file cabinets, trees and human bodies can all absorb 802.11 signals, cutting down on signal strength and transmission speeds. This even applies to small areas. For example, ABC Fine Wine and Spirits installed wireless networks in all 150 of its retail establishments three years ago, but Help Desk Manager Guy Ledbetter reports that some of the locations have “cold spots” in them where no signal is available.
To address these types of issues, Harvard’s Halamka recommends hiring an experienced firm to conduct a site survey while others prefer to keep this function in-house.
Jon James, IT Manager for the Cherokee Nation in Tahlequah, Oklahoma, has a gigabit Ethernet backbone at the main campus, but finds it cheaper to use wireless networks for remote facilities.
He and his staff conduct their own surveys using a wireless PDA with analysis software from AirMagnet. They use it to detect interference on a channel and to select the best places to locate both the access points and the computers for optimum throughput.
“A good wireless sniffer will not only aid in antenna placement and wireless surveys but will also help in diagnostics and security,” he said.
Once the access points are in place, however, they may still need tweaking to accommodate changing usage patterns. Stanford’s Noe uses AirWave Wireless’ AirWave Management Platform (AMP) to monitor his wireless network and adjust loads.
“We can see traffic load by node or system wide,” he said. “This helps us load-balance the system. We can set thresholds and, if we start to get too much traffic on one, we can move them to adjust the load.”
The other commonly-mentioned point is security. The good news is no one reported any serious security breaches. But wireless does open up an additional potential attack route into the network and proper precautions do need to be taken.
Do not deploy a wireless network without accounting for its unique security challenges is the general rule of thumb.
Halamka uses a four-tiered security structure to accommodate the different types of traffic listed earlier. Patient records have the highest level of security using for different protocols, while patient internet access only requires authentication.
Similarly, Stanford has lower security levels for the university’s guests, who only have Internet access, than it does for the students and staff who access the university’s own services.
A key action is to track down and remove any rogue access points users have installed on the network. They can be located using a site-survey device or management software. In addition to posing a security risk, rogue access points can also degrade performance.
“Unfortunately, few folks understand the concept of channel separation, power settings, encryptions, etc. They are only interested in making wireless work in their little space and don’t care about the outside world,” said James Wiedel, Director of Networking for the University of Southern California. “How many APs on channel 6 at full power and no security do you want to see in one small area?”