There’s been a lot of debate lately about the potential impact of software defined networking on switch and router manufacturers. As a counterpoint, I thought it would be useful to talk to a communications service provider about its plans for the technology so I checked in recently with Stu Elby, vice president of network architecture and technology for Verizon (News - Alert). Verizon recently did a couple of interesting demos involving SDN at the Open Networking Summit – and according to Elby, both demos targeted real world implementations that the carrier envisions for its network.

SDN is sometimes described as an approach to networking that separates the traffic and control planes and the term is sometimes used interchangeably with the term Open Flow.  But as Elby explained, they’re two separate things.

“SDN moves service intelligence, including traffic-moving decisions to software that runs in data centers,” Elby explained. “To do that the software has to control the switches.”

Accordingly, he said, “You need a communications mechanism – a language for the software to speak to the switches. That’s what Open Flow is.”

The goal of SDN and Open Flow is to enable routing and switching configurations to be adjusted on the fly through software. A couple of weeks ago, I talked to the people at the Internet2 academic and research network, who are quite bullish on using the technology to better manage really large data transfers between researchers around the world. According to Elby, Verizon anticipates using SDN for a similar purpose.

The idea would be to relieve the load on individual data centers that are part of Verizon’s network infrastructure by using software to redirect “best effort” workloads to an alternate data center in a different world region as needed. It’s one of the applications that Verizon demonstrated at the Open Networking Summit and Elby described it as “where a lot of the low-hanging fruit is” when it comes to SDN implementation.

The other application that Verizon demonstrated at the Open Networking Summit was an alternative means of supporting parental content filtering for Internet services. In a typical content filtering implementation today, all customer traffic would hairpin through a network device whether it needs filtering or not, Elby explained.

“That’s a cost burden and an operational burden and it’s a point of failure in the network,” he said.

By using SDN, Verizon hopes to move the content filter to a data center or to a mini-data center, which would reside in a central office. If a customer is registered for filtering, Elby said, the customer’s traffic will be routed to the nearest data center or mini-data center. But content requests that don’t need filtering would bypass that step, creating greater network efficiencies.

Verizon envisions that the service would be controlled through a portal that parents could set up on the fly.

Next steps

It turns out that Verizon is already doing a trial of SDN to support the delivery of video content to wireless devices. When customers request video from Netflix or another video content site, Verizon wants to route the traffic in the best way and make sure the quality is adequate, Elby said.

“People would rather see a slower bit rate, continuous stream than one that keeps freezing,” he said.

In Verizon’s trial deployment, SDN gauges the throughput available at a cell-site and if it’s not sufficient to support a full bit rate stream, traffic is moved to a trans-rating engine that slows down the bit rate.

As for other SDN deployment plans, Elby said, “Over the next three years we will look at very specific applications tied back to our data centers.”

Elby also envisions that Verizon will want to deploy hybrid switches that would allow some resources to be controlled by Open Flow, while other resources would be configured to work as they traditionally have done.