SDN is a great new way to think about the networking. But, till today, it was difficult for a software-defined network to communicate with the external world.

SDN重新定义了网络架构，但是直到今天，SDN网络仍很难与外部网络进行通信。

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The approach aligns with the trend toward SDN (software-defined networking) and NFV (network function virtualization) among telecommunications operators, thanks to its elastic and virtualization-friendly cloud architecture.

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That is causing network bottlenecks and creating opportunities for technology called software-defined networking, or SDN.

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The protocol, which was initially conceived by a graduate student at Stanford University named Martin Casado, represents a new way to control network switches and routers that has come to be known as software defined networking, or SDN.

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