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Early OpenFlow user details 'exciting' benefits

Hosting provider Genesis deploying programmable switching technology in Illinois data centers

By , Network World
August 16, 2011 12:38 PM ET

Network World - OpenFlow promises to make networking more programmable, and one early user is reaping the initial benefits.

Genesis Hosting Solutions of Lake Zurich, Ill., implemented OpenFlow in February to make its network more flexible and easier to configure. It helps the hosting provider deal with a large number of VLANs and overcome the challenges of Spanning Tree's reconvergence time in a network. OpenFlow also helps Genesis establish redundant connections while maintaining performance.

"It basically creates a network without loops in a mesh configuration, but without Spanning Tree," says Genesis CEO Eric Miller. "That was really exciting to us."

FAQ: What is OpenFlow and why is it needed?

OpenFlow is a protocol that enables software-defined networking, which means that users can define flows and determine what paths those flows take through a network, regardless of the underlying hardware. OpenFlow can take control of how traffic flows through a network out of the hands of the infrastructure -- the switches and routers -- and put it in the hands of the network owner, individual users or individual applications.

This capability could allow users to craft policies that find paths with available bandwidth, less latency or congestion, and fewer hops. OpenFlow proponents say it is particularly useful for load balancing, flow control and virtual networking in data centers, private clouds and campus LANs where devices are multiplying and straining network topologies like Spanning Tree, which can take tens of seconds to reconverge after a topology change.

OpenFlow, the result of a six-year research collaboration between Stanford University and the University of California at Berkeley, uses a centralized controller to process those reconfigurations on behalf of OpenFlow-enabled switches.

Genesis finds that OpenFlow can reroute traffic around deactivated links between cascaded switches, or around some anomaly downstream that can't be detected through link "beaconing" techniques, which ping for link status but might lack rerouting capabilities. With an API into switch tables, OpenFlow controllers allow Genesis to easily steer traffic around trouble spots and overly congested links, and control the entire switch fabric "from a bird's eye view," Miller says.

INSTANT EXPERT: All you need to know about OpenFlow

OpenFlow also allows Genesis to create policies based on its hosting customers. These policies can be easily added to or removed from the entire switching fabric so provisioning and de-provisioning of network resources for customers can be achieved through a single API call, Miller says.

Miller says that capability "was exciting to hear" when he was initially evaluating OpenFlow. "You hear about a technology and you ask, 'How well accepted is it, how implemented is it?' We would implement it in a small forum just to see how well it worked."

So far, it's working as advertised, he says. Genesis has two NEC ProgrammableFlow controllers -- one for redundancy -- in its Chicago data center governing two NEC 48-port, 1Gbps Ethernet ProgrammableFlow switches. The environment is supporting 2,500 virtual machines.

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