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Mesh Moves Into the Wireless Office

Outlook: Nascent 802.11 meshes make network installs and changes a snap. But compared with traditional wireless LANs, mesh networks have throughput limits and, for now, lack multivendor interoperability.

By Joanie Wexler
November 29, 2004 12:00 PM ET

Computerworld - A costly and complex aspect of today's wireless networks can sometimes be the very component they're supposed to eliminate: cabling. Emerging 802.11-based mesh networks attempt to resolve this irony by using more radio spectrum and less wire in the form of Ethernet cabling than traditional wireless LANs.

These are early days for WLAN meshes, but proprietary infrastructure products are commercially available. Organizations with difficult-to-cable environments and those that frequently move their WLAN nodes are among mesh's early adopters.

A wireless mesh infrastructure is, in effect, a router network minus the cabling between nodes—with the inherent rerouting for fault tolerance that such networks deliver. It's built of peer radio devices that don't each have to be cabled to a wired port like traditional WLAN access points (AP) do. Rather, each simply plugs into an AC power supply. It automatically self-configures and communicates with other nodes over the air to determine the most efficient multihop transmission path.

Today, the way these functions work is unique to each vendor. So enterprises that build mesh networks will likely use one vendor for a few years until standards are in place.

"Mesh is a reasonably important enterprise architecture going forward, because it dramatically simplifies installation," says Craig Mathias, a principal at Farpoint Group, a consulting firm in Ashland, Mass. "You take a node out of the box, plug it into the wall—end of discussion."

Supplying power to a mesh node can still be problematic. However, electrical outlets are usually far more abundant in buildings than Ethernet ports are, Mathias notes.

Only devices at the very edge of the wireless mesh hit wire—either to connect to a network switch or to stand-alone cabled devices such as printers and video cameras.

A design goal is to minimize the number of those wired devices and allow network managers to easily move wireless nodes as needed for capacity and coverage.

In a wireless mesh network, as devices are added and moved, the network automatically discovers topology changes and adjusts traffic-forwarding paths to optimize throughput.

Urology Clinics of North Texas replaced a traditional WLAN with a meshed Access/One system from Strix Systems Inc. in Calabasas, Calif., for just this reason. "We had intermittent problems with interference and shifting coverage holes," explains Kyle Nash, IT manager at the Dallas-based facility. This required him to frequently move APs to tune the network, which was laborious and time-consuming because cabling ran from each AP to an Ethernet switch.

"Now I just move APs on the fly. This means the network is up longer. It will also make things much easier as our network continues to expand," says Nash, whose goal is for the five-office, 200-plus user facility to eventually be about 90% wireless.

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