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Corsa Builds a Purely OpenFlow Data Plane

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Corsa Builds a Purely OpenFlow Data Plane

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Corsa Builds a Purely OpenFlow Data Plane

Startup Corsa is developing OpenFlow 1.3 switches as an alternative to traditional switches, calling the result a programmable data plane.

The company is announcing its presence on Monday ahead of next week’s Open Networking Summit.

Corsa’s DP6420 and DP6240 are essentially switches, but they’re designed for pure OpenFlow environments. They would seem to be best suited for greenfield situations: new networks where software-defined networking (SDN) reigns, or current networks that have purely OpenFlow-based regions being added.

In these cases, the role of the switch changes, starting with the SDN tenet of control and data planes being disaggregated — which is partly why Corsa is distinguishing its gear from regular switches.

“You’re taking a traditional switch and separating it out. What we have is a pure OpenFlow data plane,” says Carolyn Raab, Corsa’s vice president of product management.

As an aside, Corsa’s efforts also show the power of field-programmable gate arrays (FPGAs), programmable chips that arguably have caught up to fixed-function chips in terms of capability and power consumption. What Corsa did in FGPAs took only $4.2 million in funding (a round led by Celtic House Venture Partners), whereas developing its own ASIC would take tens of millions of dollars.

Banking on OpenFlow 1.3

That Corsa runs OpenFlow 1.3 is important, because that’s the OpenFlow version that supports multiple flow tables. These tables are at the heart of how the OpenFlow protocol works, as they tell a switch how to handle certain flows. But OpenFlow 1.0 used only one table, which presented a problem when dealing with larger and larger networks.

“That’s why we jumped to OpenFlow 1.3: multiple tables and group tables. That’s significant progress for OpenFlow, because that’s what’s needed to do anything at this scale,” Raab says. (The DP6400 boxes can scale to millions of flows and tens of thousands of flow modifications per second, Corsa claims.)

Corsa’s timing is pretty good, as most hardware doesn’t fully support OpenFlow 1.3 yet. NEC was early to support multiple flow tables but did so before the standard was established. (NEC did release the first OpenFlow 1.3 controller, though.) Startup Centec offers an OpenFlow 1.3-compatible switch chip, but Centec is a small player in a market dominated by Broadcom.

The DP6420 has 48 10-Gb/s ports and four 40-Gb/s uplinks, while the DP6440 has four 100-Gb/s ports and 24 10-Gb/s ports. The devices are in the hands of very early customers; general availability will happen later this year, Raab says.

The FPGA Path

In place of doing an ASIC to handle OpenFlow or using a general-purpose processor, Corsa turned to FPGAs from Xilinx. FPGAs have gotten useful enough — and frugal enough on power consumption — to provide Corsa a viable alternative to using off-the-shelf processors or developing its own chips.

Corsa also liked the programmability of FPGAs, meaning the data-plane appliances could be tweaked easily.

That’s useful as standards change or as OpenFlow adds features, but “I would put the emphasis on the changes in the use cases and the applications,” Raab says. “You see it every day. Many people have many definitions of what SDN would ultimately look like. There will be a variety of deployments and architectures before the industry and the market settle on a few flavors.”

The other advantage, though, was that FPGAs are much cheaper than ASICs.

“To do all of the chip I would need, I’d need $20 million to $30 million. And then I’d be in the business of managing a supply chain,” says Bruce Gregory, Corsa’s CEO. Corsa wasn’t anticipating sales volumes that would recoup that money. (It also would have taken a couple of years to bring an ASIC to market.)

Nothing prevents an established switch-chip company like Broadcom to design a chip to do what Corsa does. But Gregory doesn’t expect any immediate competition from that direction. “Broadcom will build chips, but not right now. They just release Trident II. They’ve got to get that money back,” he says.

Based in Ottawa, Corsa has about 20 employees. Its CTO and VP of engineering, Yatish Kumar and Stuart Reid, both worked at Catena, an access-network equipment vendor acquired by Ciena. in 2004. Gregory’s chip-company past includes LSI and Extreme Packet Devices, which was bought by PMC-Sierra during the bubble days of 2000. Raab previously worked at Quake, which was eventually acquired by AppliedMicro.

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