Network Computing is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Wired Networks Face Limited Future

Dirk Gates, CEO of Xirrus, the wireless networking company, sat down with Jonathan Feldman and Lorna Garey at Interop 2011 in Las Vegas, a UBM TechWeb event, to discuss his company's wins at Carnegie-Mellon University and the Port of Houston, as well as the future of wired Ethernet.

InformationWeek: Some IT pros have concerns over the very limited range of 802.11a, especially in buildings, and the efficacy of beamforming techniques. An iPhone, for example, doesn't have a directional array, and it can't communicate back through all that concrete.

Dirk Gates: Actually, it can. Think about a megaphone. If I put a megaphone up to my mouth and I'm shouting, you can hear me at a great distance. If I turned it around and put it up to my ear, I can hear you at great distance. So the directional antenna has gained both in transmit and receive path, so it amplifies my transmit signal, but it also amplifies the incoming receive signal. So I get a balanced link and balanced gain in both directions. I am able to maintain a conversation with you, with that directional antenna twice as far away as from our device as you would from a standard omnidirectional antenna on an AP [access point].

InformationWeek: So what you're saying is that instead of doing omni to omni, you're doing directional to omni?

Gates: Right, in both directions. So I get the advantage on both sides; that allows us to have a quarter as many devices provide the same sort of coverage as traditional APs. I have just as many radios, but they're packed into one device with long-range directional antennas instead of having to hang four devices to get the same coverage.

InformationWeek: Tell me a little bit about your field experience with this. Can you give me some examples of older buildings that might [be] Wi-Fi hostile?

Gates: A great example is at Carnegie-Mellon University. They were early adopters of .11 technology. In the late '90s, they put in 1,000 Lucent .11b access points, all of them 2.4-gigahertz only. They had coverage throughout all these dorms, with a lot of cinderblock.

But recently [Carnegie-Mellon was] looking to upgrade to .11n and 5 gigahertz, just to handle the capacity. And they correctly assumed they would need twice as many APs to be able to operate at 5 gigahertz, because the range would be less. So they were looking at going from 1,000 Lucent .11b APs to 2,000 dual-band .11n APs. And we were able to come in, do an active site survey, and actually demonstrate to them that we could cover that same area--all those dorms--with 300 of our eight-radio devices. I still have 2,400 radios in the air. But because of the directional antennas and the nature of the product, we were able to get complete 5-gigahertz coverage with just those 300 devices.

InformationWeek: What's the price point per radio that you're looking at, and what was the return on investment?

Gates: About $700 a radio. Actually, probably a little bit less. It's close to $700 at list.

InformationWeek: And you pack anywhere from four to eight to 16 in one array device?

Gates: When you take a look at [Carnegie-Mellon's] return on investment, their original plan is they were going to roll out 2,000 APs over 12 months, about 500 in a quarter. They would have to pull 1,000 new cable drops--and at union labor in Pittsburgh, that was running $750 a cable pull--and then they would have to take the 1,000 100-megabit Ethernet switch ports and put in 2,000 Gigabit Ethernet switch ports. So they were looking at $1 million.

InformationWeek: And to be clear, that's because they wanted throughput of greater than 100 Mbps at each one of these APs?

Gates: On a bonded channel you can get close to 200-plus megabits on one radio and two radios. So you're going to need more than 100 megabits ... They're going to put in 2,000 Gigabit Ethernet switch ports. We were able to cherry pick 300 of the existing 1,000 cable pulls. No new cable. Instant $750,000 savings. We were able to do this with 300 Gigabit Ethernet switch ports, not 2,000. Hundreds of thousands of dollars in savings here as well.

InformationWeek: Can you use standard PoE [power over Ethernet]?

Gates: We have our own PoE solutions. The device is large enough that it needs high-powered PoE. So they did buy rack-mounted PoE solutions from us. The alternative would have been 2,000 PoE Gigabit Ethernet ports. They did 300 PoE [ports] using our equipment.

POE today, standards-based, is less than 15 watts, and you're not going to run eight or 16 access points on 15 watts. There's a high-power PoE standard in the works, and it will get you to about 30 watts.

InformationWeek: And what do you guys drop?

Gates: About 50, 60 watts on the large arrays.

InformationWeek: You hate the Earth, don't you? [Laughter]

Gates: Well, using our PoE solution, which is SNMP-controllable, you can turn them off at night. It's programmed to go off and come back on.

  • 1