* Virtual LAN overlay was big factor in WLAN decision
San Antonio Community Hospital in Upland, Calif., installed wireless access points and switches from start-up Trapeze Networks late last year to meet high-resolution radiology and voice application requirements.
One reason why Jan Snyder, SACH’s senior telecommunications consultant, settled on the Trapeze system was that it didn’t intrude on the Layer 3 radiology network that the hospital had already built. The hospital runs a routed Extreme Networks local infrastructure to avoid broadcast storms and for high- availability networking.
A workstation for displaying images connects to an Extreme switch/router in a wiring closet, Snyder explains. For redundancy, the wiring closet is dual-connected to two core switches in the data center across two equal paths using the Open Shortest Path First (OSPF) routing protocol. The network is designed to recover in less than 100 milliseconds, Snyder says.
Surgeons access CAT scan images archived in data center servers for use during neurosurgery. Now the images are beamed across wireless LANs to PCs on rolling carts in the operating room.
“But wireless likes to be a flat, Layer-2 network,” Snyder explains. “We were faced with creating two networks and ignoring the success we’d had with wired reliability or to find a wireless system that could deal with virtual LANs.”
The Trapeze system, he explains, operates as an overlay on the hospital’s existing network. The Trapeze Mobility Exchange (MX) wireless switches in distributed wiring closets know where each user is all the time, Snyder says.
How? MXs in each subnet communicate with one another via special Layer 2 tunnels that are established when the first user roams to a new subnet. Once set up, however, the tunnel can transport client information for one or many users back to each user’s “home” subnet.
In the case of SACH’s Trapeze network, each user is, ultimately, associated with one subnet. So no configuration changes must be made to the wired side of the network for enabling all switches across an enterprise to recognize a user or client device that is roaming.
Snyder says he looked extensively at wireless vendors last summer. Capital costs were within about 30% across vendors – close enough to not be a showstopper, he says.
“The difference was in labor. We saved 70% to 90% in labor costs” for site survey, network design, troubleshooting and management with Trapeze’s automated RF tools, he says.
The ability to find empty beds via wireless communication represents a 25% increase in nurses’ performance, Snyder adds. He expects an ROI in less than a year.
