OpenFlow Nascent But Making Solid Progress

The OpenFlow protocol for enabling software-defined networking has made progress, but to analyst Rohit Mehra, it’s still more of a concept than a reality. At last week's IDC Directions 2012 conference, in San Jose, Calif., he tried to put the buzz about OpenFlow in perspective. "OpenFlow, at its core, I would say, remains a Twitter topic," said the director of enterprise communications infrastructure at the research firm. Across the pond in London, OpenFlow expert Greg Ferro took exception to Mehra’s seemingly dismissive attitude: "To say that OpenFlow is a Twitter thing is patently false," he said, then added a moment later, "but there’s an element of truth to it."

Like any technology standard, from TCP/IP to HTTP or from Flash to HTML5, the OpenFlow protocol may take years to become widely accepted and adopted as an alternative to traditional computer networking. Still, the Open Networking Foundation (ONF), a mix of academics, networking vendors and enterprise network administrators, is very bullish on OpenFlow. There are some production networks actually using OpenFlow to enable software-defined networking (SDN), but they are a relative handful. "We’ve seen some really good use cases, especially in the smaller data centers and in education environments, but I’ve yet to see a lot of traction across the generic enterprise," said Mehra.

While acknowledging that development of OpenFlow is headed "in the right direction," Mehra said OpenFlow is just one protocol designed to enable SDN and that there may be others, including proprietary ones developed by network vendors. For instance, Cisco Systems, while a member of the ONF, hinted that it may develop its own SDN protocol.

But OpenFlow advocates can point to solid accomplishments with the protocol even as they acknowledge that it is a work in progress. "OpenFlow is the first step down a long road,” said Ferro, a consulting network architect and author of a report comparing OpenFlow to traditional networks that was published by InformationWeek, which, like Network Computing, is published by United Business Media. The OpenFlow 1.0 protocol, like version 1.0 of just about anything, has its flaws, he said, and members of the OpenFlow community are working to improve on it. But there are live production networks running on OpenFlow, and there are OpenFlow-based products on the market.Indiana University’s IT network is a showcase for OpenFlow-based SDN, and Matthew Davy,chief network architect at the school, makes frequent presentations on IU’s project, including at an Open Networking Summit last fall at Stanford University. In February, HP announced that it would offer customers a free download of OpenFlow to deliver SDN capability across 16 product lines of HP networking hardware.

Also, networking startup Big Switch Networks introduced its first OpenFlow-based software controller, Floodlight, in January. Floodlight, written in Java, was released with an Apache open source license to encourage developers to write applications that deliver software-defined networking intelligence, said Isabelle Guis, VP of outbound marketing at Big Switch.

OpenFlow is a communication protocol that abstracts the data layer of a network in order to communicate, via an OpenFlow-enabled controller, with switches and routers on that network. On top of the controller is an application that issues commands to the network devices on how to operate. The point of software-defined networking is that the intelligence in the controller replaces--or, in some cases, complements--the intelligence in the network devices.

With OpenFlow, network administrators can control their network without having to go through the tedious and time-consuming task of manually reconfiguring network devices as on a traditional network, said Guis. "Network managers now can focus on contextual networks and defining rules in a software manner, making the business more agile but also integrating it better with the rest of the resources in compute and storage," she said.

However, there are already ways to automate networks without OpenFlow. A virtual LAN allows disparate network routers and switches to be operated as one network, no matter where the hardware is physically located. Devices on a VLAN can be configured through software. The Network Configuration Protocol (NETCONF) has been around for more than six years and is designed to provide a configuration interface to devices, said Ferro, who called it a "general-purpose open configuration protocol." In addition, he called Transparent Interconnection of Lots of Links (TRILL) an autonomous protocol that makes it possible for data to follow multiple paths on a network as needed.

But while those innovations automate networking in their own ways, OpenFlow is in a class by itself, he said. With OpenFlow, the software controller tracks the flow of data packets; notes their source and their destination, be it an IP address, a MAC address or a network port; and sends them on their way. "The rules say anything from this IP address to this IP address, let it happen, send it out on Port 3," Ferro explained. "What you’re effectively doing is going into the heart of the switch."

To be sure, however, not every network needs OpenFlow or needs to rip and replace the traditional network infrastructure with it. Big Switch’s Guis said customers can implement OpenFlow in one part of their network and gradually transition over to it as needed. "They can look at this as a progressive implementation and leverage their existing infrastructure," she said.

While arguing that OpenFlow is clearly viable, Ferro admits typical enterprises might be reluctant to jump into OpenFlow at this early stage. Asked what types of customers would not need OpenFlow, he answered, "anybody who’s in an enterprise or can’t afford to take a risk or can’t see a way to take a risk."

But large networks where scalability is essential, like those of service providers, are strong candidates for OpenFlow, said Nick McKeown, a Stanford researcher and co-founder of the Software Defined Networking movement. He is also a co-founder and director of Nicira, which offers a Network Virtualization Platform that uses OpenFlow. When Nicira emerged from stealth mode in February, it announced it had already signed up cloud and network service providers and other enterprises as customers, including Rackspace, AT&T and eBay.

McKeown is going to participate in another Open Networking Summit beginning April 16 in Santa Clara, Calif. While the summit last fall at Stanford was to be the first of an annual series, strong demand for information about OpenFlow prompted organizers to move the event up by six months. McKeown expects presenters at next month’s summit to provide more examples of how OpenFlow-based SDN is working in real live production environments.

"One thing is for sure," he said. "The industry is about to change in quite a dramatic way."

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