Computer networks have to support an ever-increasing array of applications, ranging from cloud computing in datacenters to Internet access for users. In order to meet the various demands, a large number of network devices running different protocols are designed and deployed in networks. As a result, network management and the deployment of new protocols and applications are quite challenging. On one hand, network operators have to manage so many different network devices and manually configure these devices using different tools. On the other hand, vendors use different physical infrastructures as well as software interfaces to manufacture devices, which makes it difficult for researchers to implement new functions in devices. Therefore, network infrastructure and architecture design face great challenges.