Switch Tiff Heats UpSwitch Tiff Heats Up
It's handbags at dawn, as WLAN infrastructure rivals dispute Vivato's definition of an 802.11 switch
February 5, 2003
The debate over what exactly constitutes a wireless LAN switch is in full swing -- well before the startups involved actually have product on the market.
Aruba Networks Inc. got in contact with Unstrung this week to dispute Vivato Inc.'s recent claims that it is the only company with a real 802.11 switch (see Vivato's Switch Bitch).
Aruba's product is a box that sits in the wiring closet and is connected via Ethernet cabling to access points in the office space and the regular wired network. It handles tasks like security, management, and allocation of available bandwidth that would normally be dealt with separately at individual access points (see Aruba's Switch Pitch).
In contrast, the Vivato switch combines a "smart antenna" switching system, which boosts the range of 802.11 signals and enables one box to replace multiple access points, with security and bandwidth management capabilities. Like the Aruba box, it is also linked back to a company's regular LAN via Ethernet cabling. Vivato claims its architecture is the only one that qualifies as a true switch, because it actually increases the overall capacity of a network, rather than simply allocating it more fairly. It says Aruba’s switch is more accurately described as a shared-media hub -- albeit a smart one.
Aruba disputes this. "We actually switch traffic based on the 802.11 MAC [media access control layer] address... and can provide rate limiting on a per-user basis," writes David Callisch, communications director at the company, in an email. "That, by definition, is a switch. A switch is not defined on whether or not it can provide dedicated bandwidth to each user but rather by how information is forwarded through the device."
Of course, Aruba couldn't resist getting a few low blows in about its rival's product as well. Vivato's offering will be expensive to implement and ineffective in indoor environments, according to Keerti Melkote, VP of marketing and one of the founders of Aruba.
Vivato says its initial 802.11b product will offer total capacity of 33 Mbit/s, support up 150 users, and cover an entire office space of up to 100 meters by 100 meters, without additional access points.
However, Aruba claims that the performance of the Vivato switch will start to deteriorate in a crowded office. If there is more than one user in a "beam" from the Vivato box, Melkote contends, then performance will start to degrade -- particularly if users are far away from the corner where the Vivato switch is installed.
"The question is really one of capacity," Melkote says. Rather than Vivato's 33 Mbit/s of total bandwidth, Aruba's distributed approach can deliver up to 2 Gbit/s of aggregate capacity, supporting thousands of users, he says. [Ed note: If we assume they're initially looking to use 802.11b access points, this means that an Aruba switch would have enough ports to support up to 180 access points, something it hasn't confirmed yet.]
However, Aruba's approach will still only deliver a total capacity of 11 Mbit/s per user if each of them has a dedicated 802.11b access point. Throughput figures start to fall off quickly once users share an AP.
Aruba also claims that Vivato's box will be expensive. They say that Vivato will charge $5,000 per beam for its unit, which means a total cost of $15,000 for the initial product. Individual access points range between $100 and $1,000 for each box. However, it is actually difficult to do a real cost comparison between Aruba's and Vivato's putative products, because neither company will deign to talk about pricing.
The Vivato box is costly because it is derived from military technology, contends Carl Temme, director of marketing at another wireless LAN infrastructure startup, AirGo Networks. AirGo is barely discussing the technical details of its products yet, but naturally it believes its approach superior to its rivals.
Temme's firm, which was formerly known as Woodside Networks, is working on a similar WLAN antenna technology that will be much cheaper than Vivato's offerings, he claims, because it uses digital signal processing technology and commercial antenna systems [ed note: more on this soon].
Temme contends that Vivato's multipath "beam following" technology does not work well indoors, because the concentrated signal bounces off walls and cubicles and doesn't corner well.
A spokesperson for Vivato denies this, saying that the system works well in a normal office environment. "The signal can't get through thick walls or metal," she allows. Vivato is expected to unveil the details of its first product in a couple of week's time.
So what do you think, readers? Just what do you class as a wireless LAN switch? We'd be interested to hear your comments. Just click the "Discuss This Story" button at the bottom of the page to make your voice heard on this contentious issue.
— Dan Jones, Senior Editor, Unstrung
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