Wireless mesh or WiMAX: Which MAN technology is best?

Enterprises give wireless mesh a whirl -- and they like the ride.

Not too long ago, enterprises had limited options when it came to making a wireless network part of the New Data Center plan. In the local area, the choice was Wi-Fi - 802.11b, g or a. In the larger campus or metropolitan area, people anticipated widespread WiMAX deployments (aka 802.16d or 802.16e) because of the promise of broadband-level bandwidth, improved flexibility and tight security.

Not so anymore. These days, metropolitan wireless mesh networks threaten to leave WiMAX at the gate. The reasons are numerous: They follow the traditional Wi-Fi standard, so any Wi-Fi-enabled client can work with them, users and analysts say. Plus, they don't require wire runs to every node, they are designed to be self-organizing and -healing, and they scale on the fly. If you need more capacity, add another node, and you've got it.

In addition, mesh gear is available from Cisco, Firetide, Strix Systems, Tropos Networks and others. WiMAX products are not nearly as prevalent. Fixed WiMAX equipment is just coming to market, and mobile WiMAX gear is not expected to arrive much before late 2007.

"I looked at WiMAX in the public safety arena. . . . It worked great in a stationary environment, especially for video cameras, but once I tried it in a mobile environment, it didn't work," says Peter Collins, CIO for the city of Austin, Texas, which recently deployed a series of wireless meshes using Cisco Aironet 1500 series gear.

That's not to say mesh is always the best choice. For most companies considering deploying in-building wireless networks, the cost equation indicates traditional Wi-Fi is still the way to go - if the wire is there and available for the Wi-Fi access points. But when the infrastructure has not been wired, and running wire would be prohibitively difficult or expensive, mesh makes sense. "Mesh works well, and we're starting to see it in warehouses, loading docks, logistics, transportation, those kinds of applications. We also see it in large, temporary setups, like outdoor concert venues," says Craig Mathias, principal at the Farpoint Group.

For example, North American Midway Entertainment, a large amusement company in Los Angeles, sets up Firetide wireless mesh networks to support transaction processing for its fairs and carnivals. Firetide's HotPort mesh network gear provides reliable, robust connectivity in a challenging environment, says John Gallant, North American Midway's CIO.

"For us, it's almost impossible to use a conventional wireless network with point-to-point runs and wireless access points," he says. "The Firetide mesh gives us a multipoint setup. We can actually go around corners. If the connection's strongest point is straight in front of you, but every three minutes a huge mechanical device like a ride goes past it for a minute, that creates a lot of delay and latency. With the Firetide gear, if one node becomes obstructed or the network noise level gets too high, the node will automatically route the signal to the next best possible route," he adds.

In mesh networks, users deploy multiple mesh nodes throughout an area, but, unlike in traditional Wi-Fi, only one node has to be connected to a wired network. When a mesh node receives a frame from a Wi-Fi client, it relays the frame from node to node, until the frame reaches the wired node. Each node has a standard Wi-Fi interface, to communicate with clients, and a radio-based backbone link that relays the message across the network.

Because the mesh doesn't require wire runs to every node, Gallant can use it in the large spaces he needs to cover. For example, North American Midway recently ran the Canadian National Exhibition in Toronto, where the fairgrounds blanketed about one square mile. Gallant implemented a mesh comprising 42 nodes and access points. It supported 240 users.

Mesh has its downsides, he says, but those are common to all wireless networks - susceptibility to lightning, interference from other devices, power outages. Most problematic is having to plug nodes into standard, 110-volt household receptacles. "They have battery backups in case you lose power, but you do have to plug them in. That's probably the biggest challenge," Gallant says. Still, reliability outweighs the downsides: "Mesh works great," he says.

Proprietary routing standards

A bigger downside for some users considering mesh networks is the proprietary nature of each vendor's routing scheme. That means once you make the decision to buy, you're locked into that vendor. Although the IEEE is working on a standard routing protocol, called 802.11s, it doesn't expect to finish that work until late 2007. Even then the standard would provide for fairly vanilla multivendor mesh implementations.

This gives some users pause. "Wireless mesh is a little bit out there," says Elliot Zeltzer, global manager for telecommunications security at General Motors in Detroit. "We can't afford any downtime. We're looking for more established, standardized technology."

Mesh vs. WiMAX

 Wireless mesh (Wi-Fi)WiMAX
Bandwidth11M or 54Mbps70M to 100Mbps
Coverage

No limit

No limit
AvailabilityNowtBy year-end 2007

GM is in the middle of a traditional Wi-Fi rollout across its campus, primarily because the wiring is there and it's a more proven technology, Zeltzer says. If he were to look at a more metropolitan-level rollout, he says he'd favor WiMAX.

"Not speaking specifically to GM, I believe WiMAX has the highest value," Zeltzer says. "It offers huge amounts of bandwidth for fairly low cost and in the end, it could provide total local-carrier bypass," he says. Plus, Zeltzer says, he is leery of mesh security.

Wireless mesh users counter such arguments by saying mesh offers enough coverage, bandwidth and security for today's applications. "Everything's misleading in the world of wireless, and your rate depends on a lot of factors, like distance and interference," Austin's Collins says. "With WiMAX, your rate decreases the farther away you are from the transmitter and receiver. It's all relative. I have a consistent throughput on wireless mesh, and that's more important."

As for security, Farpoint's Mathias, as well as current users, say it's not an issue: "Basic wireless LAN security is really improved to the point where it's very good,"he says. "If you can secure a wired network, you can secure a wireless network."

In the end, the proof is in the deployments. Several cities have committed to wireless mesh rollouts, and vendors seem to be ticking off new users weekly. As Mathias says: "The demand . . . is a global phenomenon."

Cummings is a freelance writer in North Andover, Mass. She can be reached at jocummings@comcast.net.

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