To ensure that we can all watch YouTube without interruption, major Internet service providers must manage two very different switching technologies. Wide area "IP" networks made up of packet switches are interconnected over long distances by circuit-switched "transport" networks.
A typical service provider operates and manages these two networks independently, leading to a duplication of functionality and resources as well as to higher operating costs. Additionally, the two networks do not dynamically interact. For example, in response to long-term changes in demand, IP network controllers must contact circuit-switch network controllers, who adjust the long-distance pipelines by manually plugging in new circuits that increase or decrease the bandwidth.
"This is a long, drawn-out process that can take days or week to accomplish," said Guru Parulkar. He and his team at Stanford University have developed a way to merge the two network architectures that could allow Internet service providers to cut costs and to respond more flexibly to the needs of their users.
Past efforts to bridge packet-based and circuit-based technologies have approached the problem with the assumption that the two networks, which have very different architectures, must remain distinct. As a result, trying to span the two networks has resulted in very complex solutions. The transformation of circuit-based technology to IP has vastly changed this equation as both packet-based and circuit-based applications run on the same IP platform. But little has been done to show the possibility and consistency of a uniform solution.
The OpenFlow project takes advantage of this architectural evolution in the direction of true convergence. It merges the two types of networks by blurring the distinction between packet switches and circuit switches, presenting them both as "data-plane" flow switch abstractions (that switch at different granularities) to an external, decoupled "control plane." Such an abstraction is achieved between the controller and the switches via the OpenFlow protocol. This then enables new capabilities that can exploit the mix of switching technologies dynamically.
For example, the "controller can configure a circuit in seconds instead of days or weeks," said Vinesh Gudla, one of the students working on the project. Gudla will present a set-up of two packet switches connected by a circuit switch that uses OpenFlow to stream video.
The research is being presented at the Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC) -- the world's largest international conference on optical communication and networking -- from March 21-25 at the San Diego Convention Center.
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