A mesh mash of opinions on WLAN architecture

A wireless LAN (WLAN) mesh architecture is supposed to make these networks easier to deploy and manage, but not everyone is convinced of the benefits.

That seemed clear during a panel discussion of mesh architecture for WLANs at Wi-Fi Planet, a wireless technology conference in Toronto running from March 16 to 18. The seminar brought together a number of mesh-architecture WLAN vendors and one traditional WLAN vendor to talk about mesh network deployment.

Mesh networks are meant to address distance and capacity limitations of WLAN equipment. In traditional WLAN topologies, each access point requires its own wired connection to the enterprise network core. But sometimes buildings do not have the requisite cable infrastructure to support multiple access points. The mesh architecture reduces the need for cable, creating connections between a number of access points so just a few of them require a wireline link to the core.

Lynn Lucas, director of marketing at Proxim Corp., which sells traditional WLAN equipment, said the mesh architecture is good for locations that lack wireline infrastructure, such as outdoor implementations. However, mesh networks also have certain problems. For instance, Lucas said companies that lack enough wireline infrastructure to support a hub-and-spoke WLAN model sometimes also lack the electricity outlets required to power access points. If an enterprise has to roll out electricity, it might as well use the standard Power over Ethernet (PoE) technology and bring both data connectivity and power to the network nodes. Once the wires are in place, the mesh advantage becomes “moderate if not little,” she said.

But Doug Huemme, director of marketing at Strix Systems Inc., a mesh network vendor, said “in very few environments that’s true,” the data-wire and electricity infrastructure is equally thin. Still, he added, even if a building lacks the requisite Ethernet cables, chances are it has electricity. After all, most office towers were retrofitted with electricity nearly a century ago. It’s much more ubiquitous than Ethernet.

Frederick Harris of Firetide Inc., another mesh WLAN vendor, said Lucas is wrong to suggest mesh implementations have limited value. He said enterprises could use this architecture to extend their wireline LANs to unwired buildings, or outside to cover a campus with Wi-Fi.

Lucas also said that some mesh architectures hinder network performance, as they call upon the access points to do double duty as both a client-facing data access provider and a back-end connector that speaks to other access points in the network.

But Phil Belanger, vice-president of marketing at BelAir Networks Inc., pointed out that his company separates the client-facing access and the back end. In BelAir’s case, that means end users connect to the network via the 802.11b wireless protocol, while the access points speak to each other via a variant of the 802.11a protocol. The upshot: BelAir’s access points do not divide their capacity between end-users and maintaining the mesh connections.

Huemme from Strix said the mesh architecture aids network maintenance. “You have to take into account the number of adds, moves and changes,” he said, pointing out that it’s more difficult to relocate enterprise end users on a wired network than it is to move them around a wireless network. A meshed wireless environment could help cut down on the IT department’s workload.

Lucas said Proxim’s access points can work as repeaters to provide a connection between network nodes, but Harris said this bridge-type system is only as good as each access point. If one goes out of service, the entire data chain collapses. The mesh architecture, he said, routes around broken links, so if one access point is lost, the entire infrastructure doesn’t disappear with it.

Lucas said Proxim has not ruled out its own mesh network product line, but in her company’s opinion the technology will speak to a handful of customers, particularly those that are trying to deploy Wi-Fi out of doors.

Rosario Macri, a product manager at Mississauga, Ont.-based wireless network provider Psion Teklogix Inc., said his company is investigating the mesh architecture to see if it would suit its clients — enterprises that want to put WLANs into warehouses and shipping depots. At the end of the mesh discussion, Macri, a Wi-Fi Planet attendee, said the mesh architecture sounded just right for his firm.

“One of our big markets is…shipping ports,” he said. “Unless you have poles lining the dock, you’ll have trouble installing the wires.”

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