"We have a kind of perfect storm in the networking sector. There's an incredible opportunity for startups," said Appenzeller.
Big Switch and another firm founded from Clean Slate researchers, Nicira, and the major virtualization vendors Citrix Systems and VMware are beginning to form a consensus that the best way to get to virtualized network resources is through OpenFlow.
OpenFlow is a protocol that opens up each network device's flow table to a remote controller, which can send it instructions on a dynamic basis that assign and reassign bandwidth and other network characteristics, including security. OpenFlow would replace spanning tree in each switch and router. It's not the only approach, but at the moment it's the best possibility with the widest backing.
The Open Networking Foundation has been created to oversee the ongoing development of OpenFlow. Founding members include Deutsche Telekom, Facebook, Google, Microsoft, Verizon, and Yahoo. In addition to Microsoft, virtualization vendors Citrix Systems and VMware also are part of the foundation, and they see the problem clearly, partly because they are heavily invested in the idea of a flexible, elastic set of resources in the data center, instead of hardware. They solved their part of the problem--networking within the virtualized server--with a software switch in the hypervisor. They know the difference between a software-defined network and a hardware-defined network.
Of the two, Citrix is the more outspoken on the value of a software-defined versus hardware-defined network: "OpenFlow has the right mojo and the right design principles baked in to be one of the biggest things that will show up in networking in the next five years," predicted Sunil Potti, VP of product management for the Networking and Cloud Group at Citrix, in an interview.
Citrix has worked closely with Nicira, one of the first to produce a commercial OpenFlow supporting switch, the Nicira Open vSwitch. Eighteen months ago, Randy Bias, CEO of Cloudscaling, wrote in his blog about a Citrix decision to include the Nicira Open vSwitch as the software switch in its private cloud software stack. Bias said: "Nicira is commercializing the OpenFlow switch specification. OpenFlow is a very important change in the way we build, design, and manage network infrastructure."
In response to a query, Bogomil Balkansky, vice president of product management at VMware, said: "VMware is one of 80 participating members of the OpenFlow Networking Foundation that supports the advancements of OpenFlow. We are actively monitoring the space as the standard continues to mature to meet the demands of our customer base. We agree with the problem statement OpenFlow aims to solve and believe programmable networks will be the way of the future."
This is less concrete than Citrix's action. "Actively monitoring" can also mean sitting on the sidelines, although VMware built OpenFlow characteristics into its hypervisor software switch. I should reserve the "sitting on the sidelines" descriptor for Cisco's ONF membership. OpenFlow, if it takes hold, will be disruptive to existing networking vendors. VMware certainly sees the virtualization potential of OpenFlow.
There are still concerns about OpenFlow. One is security. The fixed network has certain security attributes that seem to go out the window if we make the forwarding tables of different vendors network switches available for programmatic direction. It's not clear how OpenFlow will allow for sufficient security to replace what's been lost, or how many new exposures it opens up.
Nevertheless, OpenFlow has emerged as the best path to the next phase of data center virtualization, the addition of the network as another of the pooled resources available for the virtual machine. As it becomes more widely adopted, it will represent a giant step toward that flexible, adaptable computing resource we hope one day to have at the heart of every business.
Charles Babcock is an editor-at-large for InformationWeek.
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