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WLAN standards diverge as Nokia joins "power over Ethernet" club

Claiming that its new access point "will bring style and convenience to public wireless LANs" Nokia has quietly joined the club of those who are powering access points from the network itself. But there's a catch, or two ... standards.

When Cisco won the contract to provide the WLAN access point hardware to BT for its "public hotspots" service for public Internet access, one of the selling points Cisco boasted about was its ability to use the Ethernet cabling which provides data to the access point, to also carry the (very small) electrical power needed.

"We have Cisco 3524XL, because that allows inline power to the access point," said Andrea Vocale at Cisco, at the time of BT's launch. "It not only powers the AP over Ethernet, for distances of over 100 metres, but obviously reduces the cost of installation."

Nokia has now jumped on the hotspot bandwagon with the launch of its A036 Wireless LAN Access Point - dealing mostly with its suitability for exposure in public, because of its "style and convenience."

This device too has Power Over Ethernet, PoE - and you would tend to assume that two major standards-following organisations like Nokia and Cisco would adopt the same protocols for this. You'd be dead wrong, and you'd risk blowing up your expensive access points.

Unfortunately, when the Wireless Ethernet Compatibility Alliance was formed, it was concerned with with wireless side, rather more than the Ethernet side; and there is no WECA recommendation for how to provide power to an access point via the Ethernet cabling. Worse; the completely arbitrary decision of which wires to use was made in a completely arbitrary way, with no consultation to see if existing standards existed.

An excellent description of the resulting mess can be found at NYC Wireless in a "how-to" article showing how to feed power into unused Ethernet wires, and take it out the other end.

The author, Terry Schmidt spells it out: "WARNING: Don't try this unless you have some electric clue. 12v isn't going to kill you, but you may cause serious damage to your access point and other equipment. Don't blame me if something goes wrong. I'm not an electrical engineering major, I'm just a networking guy who wanted cheap PoE modules, and decided to write about how I did it."

And, he adds: "Also there is no set standard (as of 03/19/02) as to which pairs get the positive power, and which pairs get the negative power. Measure your equipment carefully so you don't damage it."

Worse still, Schmidt observes, there is already a divergence. He recommends the Intel, Symbol, Orinoco Standard, not the Cisco standard for wiring. Get it wrong, and [BANG!] - your AP may be no more than a warm collection of silicon ex-circuitry.

Nokia's point about "decorative style" in equipment which is going to appear in public is well taken. "The owners of public places are often understandably reluctant to allow unsightly telecom infrastructure to be installed on their premises," says Matti Mikkola, senior industrial designer, Nokia Networks.

"That's why we went directly to them when designing the Nokia A036 Wireless LAN Access Point," Mikkola continued. "We wanted a clear idea of what property owners require in such equipment. We interviewed the staff of airports, hotels, shopping malls and conference centers, and the results were very informative. We found their major requirement was a discreet visual design."

Whether Nokia has actually succeeded, is another question. Several AP manufacturers provide very discreet little units which don't require wall mounting; and wall mounting is inevitably going to be much more costly than ceiling mounting in the typical public building. Most office areas have wiring in the ceiling already, and it's easily accessible; the walls tend to need cutting and re-plastering - not cheap, nor decoratively appealing!

Security: Nokia's A036 Wireless LAN Access Point is 802.11i-compliant - it uses the "interim fix" for WEP vulnerability known as "Temporal Key Integrity Protocol" or TKIP. But the claim is that it provides for future-proof upgrading - it can be remotely software-upgraded to the 802.1x, 802.11i/TKIP, and 802.11f IEEE standards from the network management center as standards become finalized.

There are other issues for public hotspot access, of course; Nokia has evolved its own non-standard technique here, too, with something it calls the "Privacy Zone" - concerning which its functional specification is pretty reticent.

The product will be available in volume deliveries in June 2002 through Nokia and IBM sales channels, according to the full press announcement put up today.