Wi-Fi mesh standard inches forward

802.11s, the nascent mesh extension to the 802.11 wireless standards suite, reached a milestone at last month’s IEEE 802.11 Task Group S meeting. The group agreed to merge two remaining technology proposals into a single joint proposal that, per the group’s meeting notes, represents “the starting point for the 802.11s standard, although much work remains.”

Wi-Fi mesh is at the heart of most of today’s municipal Wi-Fi networks. It is also used in private business networks that are prone to frequent topology changes, have unusual cabling challenges, and are transient in nature (such as construction sites and roadshow-style events). In the absence of a standard, meshes are built today using equipment with proprietary protocols – the “secret sauce” of mesh suppliers.

A final standard, like most computer networking standards, would facilitate multivendor interoperability and lower prices. It will also force today’s start-up suppliers to differentiate themselves architecturally, according to Roberta Wiggins, a mobile/wireless research fellow at the Yankee Group. Wiggins authored a report, “Myths and Realities of Wi-Fi Mesh Networking,” published in February.

To date, start-ups such as Bel-Air, Firetide, PacketHop, SkyPilot, Strix Systems and Tropos have built businesses out of providing proprietary protocol extensions to the 802.11 MAC and PHY that auto-configure paths between Wi-Fi access points in a self-configuring topology. These algorithms account for environmental conditions, such as wireless interference, in choosing paths.

Once a standard replaces these proprietary mesh algorithms – at least a year away – and with bigwigs Cisco, Motorola, and Nortel now in the mesh market, watch for market consolidation, Wiggins advises. Motorola already gobbled up start-up MeshNetworks in late 2004.

Wiggins points to some architectural characteristics to consider when selecting products:

* A modular architecture with dual-frequency, multi-radio support for scalability and for separating access, backhaul ingress and backhaul egress functions.

* A switched mesh configuration for greater capacity and QoS than a shared mesh.

* A single- vs. a dual-vendor architecture; in other words, do you need one vendor for wireless LAN access and one for mesh backhaul, or can you get the whole network from a single vendor?

The next Task Group S meeting is slotted for May, when the committee expects to discuss mesh network security.