Approaches to going 'all wireless'

Wireless hierarchy vs. wireless mesh

Industry analysis by expert Joanie Wexler, plus links to the day's wireless news headlines

To date, the answer to eliminating cabling beyond the 802.11 mobile access network and into the backbone has been mesh architectures. As mentioned last time, however, Meru Networks has devised a wireless alternative it says emulates hierarchical cabled networks.

Using a Meru Wireless Backbone System, client devices communicate with Meru access points (AP) wirelessly, as always. From there, the APs communicate wirelessly to the company’s Radio Switch in the “distribution” layer, explains Ihab Abu-Hakima, Meru president and CEO.

The Radio Switch - announced last year - overlays multiple channels’ worth of bandwidth for greater capacity (as would counterpart distribution-layer wired Ethernet switches). Multiple Radio Switches talk to one another wirelessly, as well. At least one Radio Switch, however, must be cabled back to the high-speed core (data center) Ethernet switch or redundant switch pair.

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To date, the answer to eliminating cabling beyond the 802.11 mobile access network and into the backbone has been mesh architectures. As mentioned last time, however, Meru Networks has devised a wireless alternative it says emulates hierarchical cabled networks.

Using a Meru Wireless Backbone System, client devices communicate with Meru access points (AP) wirelessly, as always. From there, the APs communicate wirelessly to the company’s Radio Switch in the “distribution” layer, explains Ihab Abu-Hakima, Meru president and CEO.

The Radio Switch - announced last year - overlays multiple channels’ worth of bandwidth for greater capacity (as would counterpart distribution-layer wired Ethernet switches). Multiple Radio Switches talk to one another wirelessly, as well. At least one Radio Switch, however, must be cabled back to the high-speed core (data center) Ethernet switch or redundant switch pair.

The Meru controller - which has visibility into the whole wireless network topology, tracks authentications so no handoff time is wasted when roaming, load-balances APs and handles a number of other functions -  can be cabled to the wired backbone switch for centralized control.  

The hierarchical topology contrasts with wireless mesh networks. In a mesh network, 802.11 nodes communicate with one another wirelessly in the backhaul section of the network in a flat topology. Wiring is at the “perimeter” only, between the Ethernet switch, printer, video camera, or other edge devices and the nearest 802.11 node.

Mesh is seeing a greater uptake in outdoor networks than as a replacement for cabled LANs indoors. One reason, according to Monte Seifers, director of technology at Black Box Converged Solutions Group, a value-added reseller in Nashville, is that meshes have trouble coordinating VPN security end to end.

“I would be uncomfortable with most of my customers sending sensitive information over mesh,” says Seifers, “because mesh doesn’t lend itself to encryption algorithms.” In mesh networks, the forwarding path is always changing, while VPNs are designed for connection-oriented sessions that require a single authentication.

The need for continual dynamic reauthentications in mobile networks blows that model. The new Meru system, however, operates hierarchically and has Advanced Encryption Standard (AES) built in.

In addition, the more hops in mesh networks, the less overall bandwidth is available, which isn’t the case with the hierarchical topology, according to Seifers.

Ken Winke, IT director at Optimus, a Chicago post-production house that edits TV commercials and has a 10-AP Meru WLAN, says he would “love to get rid of the cabling” for his office’s business machines and redeploy it. However, editors using high-end workstations for editing “need Gigabit Ethernet dedicated bandwidth. For them, I don’t see eliminating my wires.”

Read more about wireless & mobile in Network World's Wireless & Mobile section.

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.