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Network World - With its ability to decouple network control from the physical infrastructure, OpenFlow and software-defined networks have been touted as the Next Big Thing in networking. They've been pitched as a way for cloud service providers and webscale companies like Google, Facebook and Yahoo to ease or automate network configuration and reconfiguration, and quickly add more functionality without manually touching each and every switch or router in the network.
Such companies can use OpenFlow and SDNs to reroute traffic, balance traffic loads, provide bandwidth on demand for peak requirements, execute policies to scale and segregate the networks of different data center or cloud tenants, and connect subscribers to content and services.
INQUIRING MINDS WANT TO KNOW: What is OpenFlow and why is it needed?
OpenFlow and SDNs have also been coronated as "Cisco Killers" due to the ability to abstract network configuration and extensibility from vendor-specific hardware and software commands, ostensibly relegating Cisco switches to Just Another Device status in a network and freeing customers from vendor lock-in. But Cisco just announced its own programmability initiative through its Cisco ONE architecture and onePK software development kit (see related story) and Insieme Networks is building a line of programmable switches for the company.
Actually, there are several, vendors in the OpenFlow/SDN/network virtualization arena say.
"Our primary focus is the enterprise market," says Kyle Forster, co-founder of Big Switch Networks, a maker of OpenFlow controllers for SDNs. Big financial and technology companies are trailblazers with OpenFlow, he says.
They are using it for network virtualization for private cloud buildouts to extend beyond the limits of virtual LANs, which top out at 4,096. Once those private clouds are implemented, enterprises then look for more business critical applications for OpenFlow and SDNs, like data center interconnect, disaster recovery and granular security.
"There are all these requirements on the application for the private cloud 2.0 and that's where, on the network side, the VLAN architecture really starts to break," Forster says.
Even before enterprises implement private cloud, data center network virtualization is some low hanging fruit for OpenFlow and SDNs, Forster says. Server virtualization across eight to 30 racks, with 200 to 2,000 VMs per rack, usually breaks the VLAN limit and opens up an opportunity for SDNs.
"That's the end of the all VLANs everywhere path," he says.
But OpenFlow and SDNs are not network virtualization, per se; they are network construction tools to facilitate network virtualization, which is really a "solution" built on top of an SDN foundation, says Martin Casado, co-founder and CTO of network virtualization start-up Nicira.
Casado was also one of the chief developers of the OpenFlow protocol and API.
"The enterprise use case motivated the work that I did that became OpenFlow and grew into this SDN mania," Casado says. "Within the business enterprise, there has long been requirements for security, for isolation and for service interposition. How do you build an enterprise network that allows for security and isolation, with simplified operations and service interposition?"