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Mesh networks winning converts

By Network World Staff, Network World
May 03, 2004 12:03 AM ET

Network World - Ignoring the crimson tracery of the Golden Gate Bridge soaring into a winter sky, Mickey Griffin and George Lowry peered instead at the screen of a notebook with an 802.11b wireless LAN card.

The California Governor's Office of Emergency Services employees, taking part in a trial of new wireless mesh technology, viewed live video of one of the bridge's abutments shot by a wireless IP camera mounted on a police patrol boat.

The image itself, in somewhat grainy quarter-VGA resolution, wasn't remarkable. What was impressive, though, is that the same image was seen at the same time by 30 other people who were stationed at various points on and around the bridge.

Using traditional wireline and wireless technology to achieve this in an emergency is impossible. End users would need to be mobile, yet installing the needed number of access points to blanket an area would be complicated and pricey, and most of all, time-consuming.

"The big strength of wireless mesh is the ability to put it up and tear it down very quickly," says Abner Germanow, program manager for enterprise networking at IDC.

The Golden Gate users had devices with off-the-shelf 802.11b WLAN cards from Proxim or 3e Technologies International and an early version of wireless mesh software from start-up PacketHop.

The PacketHop software creates a peer-to-peer mesh network: Each wireless client becomes a routing node that's aware of all its neighbors and can pass data and images among them. The range depends on what kind of 802.11 radio the client has, radio power levels and antenna design. In the Golden Gate test, the WLAN radios in the NICs ran at the highest power level allowed, 200 milliwatts (by comparison, Buffalo Technologies' 54M bits/sec 11g CardBus adapter runs at 37 milliwatts). PacketHop executives say the 11b client radios meshed with each other at ranges of 1,500-2,500 feet.

PacketHop plans to release a product by year-end and has not set pricing.

Mesh nets use complex algorithms for automatic discovery, routing and fast handoffs. Nodes in a mesh find each other and can route around failures or congestion. Vendors say these multiple pathways boost the reliability and capacity of wireless networks. There is no single point of failure, as there is in traditional hub-and-spoke networks.

Mesh networks minimize the need to install Ethernet cable and electrical wiring, which are the most costly and time-consuming elements of WLAN deployments.

"Wireless mesh offers enterprises a way to get around the big paradox of WLANs, that is, they are wired [to the backbone]," says Sarah Kim, a wireless market analyst with The Yankee Group.

Obstacle course

One obstacle is that the technology, which has been used in military nets, is new to the civilian market. PacketHop doesn't even have a commercial product yet.

There are also no industry standards. The IEEE 802.11 committee has just created a task group for forming a mesh network standard. A final standard probably is two to three years away.

IDC's Germanow cautions that one of the classic problems in a mesh network is the traffic that the networks' auto-discovery mechanism generates. "When you get into a large number of nodes, then the routing traffic volumes can take over with all the nodes saying 'Here I am,'" he says.

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