NEW YORK -- Ethernet Expo 2012 -- Software-defined networking (SDN) can do a lot of things, but one application emerged as the favorite among the Carrier Ethernet crowd: dynamic bandwidth allocation.

The ability to increase or decrease bandwidth on demand came up during multiple sessions Tuesday as speakers expounded on why they think SDN is going to be important in the Ethernet services sector.

SDN encompasses a lot more than that, of course. The model espoused by the Internet Engineering Task Force (IETF) is one of programmability, issuing commands to different layers of the network via APIs. This view is also how Heavy Reading has chosen to look at SDN, analyst Stan Hubbard said.

For Ethernet service providers, however, there's a more immediate need. "Bandwidth-on-demand is inevitable. It has to happen to match the cloud operations," said Ralph Santitoro, director of Carrier Ethernet market development for Fujitsu Network Communications Inc. , during a Tuesday morning keynote.

It's also the kind of feature that's sellable and easy to explain, and that made on-demand bandwidth the star application whenever speakers needed to discuss SDN's potential benefits.

Plus, it's already being done. tw telecom inc. (Nasdaq: TWTC) has already started moving in this direction with its Telco 2.0 offerings, which include a portal for customers to temporarily double or triple their bandwidth provisions.

Other carriers like the idea, too. Glenn Calafati, vice president of product development at service provider Sidera Networks Inc. , talked about his ideal SDN console, with simple knobs to dial optical and Ethernet bandwidth up or down, and to do the same for quality of service (QoS).

Bandwidth-on-demand could be useful for delivering video, but a more workaday application would be in cloud computing, as Santitoro alluded to, because cloud architectures lend themselves to sudden bursts of traffic. And extra bandwidth during those bursts is something customers would pay for -- extra revenue that might otherwise go to some other service provider, Santitoro said.

Another example, described by Vijay Raman, vice president of product management at Overture Networks Inc. , was a kind of bandwidth "family plan" for a large enterprise. The company had a lot of sites and purchased an aggregate amount of bandwidth for connecting them, with the ability to apply that bandwidth to whatever connection needed it.

When it comes to dynamic bandwidth allocation, some standards might soon be on the way. Speaking Wednesday morning as a MEF representative, Santitoro noted that the MEF is working on standard Ethernet-services definitions that would be "more dynamic, elastic and on-demand, to better match the way cloud services work."

Show me the money
Vendors and the media have been obsessed with SDN, but it's important to remember that it's a relatively new subject. "There's a lot going on, and the interesting thing is, we didn't talk about any of it [at Ethernet Expo] a year ago," Hubbard said.

In that sense, it's important for SDN to latch on to applications that sound relatively easy to attain and come with easily sellable benefits.

"Show me the money. How do you monetize that, and how do you put something on the shelf that customers are going to use?" stated Sidera's Calafati.

He also challenged the vendors to help. "If we're going to allow these devices to manipulate and control the network, then the vendor community has to step up," he said. "A lot of guys are talking about it -- who's taking the lead?"

That's along the lines of what Margaret Chiosi, an executive director at AT&T Inc. (NYSE: T), said Tuesday -- that vendors need to help make SDN happen. Chiosi was talking more in the context of vendors being less interested in boosting the value of software at the possible expense of hardware margins.

But that's where the networking industry is headed, regardless of what you call "SDN," said Marc Cohn, senior director of market development at Ciena Corp. (NYSE: CIEN). The value in a product is moving out of the hardware and into the software and the control plane, he said.

None of this means SDN needs dynamic bandwidth allocation in order to succeed, though. In a recent Heavy Reading webinar, 15 percent of the participants reckoned they're already doing SDN but just never called it that, Hubbard said.

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— Craig Matsumoto, Managing Editor, Light Reading