Timed Data Plane Update in Data Center Network SoftwareDefined Networks make it more principled and formal to operate and verify networks, which decouple the control plane and the data plane and introduce flexibility and programmability into the network. The SDN control plane needs to frequently update the data plane. However, the decoupled control and data planes face new challenges. The network is still an asynchronous distributed system in rule updates. If the update operations are not carefully scheduled, it may result in blackhole, congestions, and violate the consistency properties. Motivated by the tightly synchronized SDNs, we proposed TIDERS Algorithm for consistent network updates in timed SDNs  where one node update can be scheduled at specific time. In TIDERS, we use synchronized time technique to achieve fast network updates while guaranteeing consistency properties. We focus on congestionfree in scheduling the update operations. To achieve this, we first set up a flowbased dependency graph and transform it into switchoperation level dependency graph. Based on operation dependency graph, we generate an update schedule and gradually optimize it to finally get a fast update schedule. After that, we conduct a series of simulations comparing our approach with several other methods to evaluate it.

A comprehensive survey of interface protocols for software defined networks Abstract   Software Defined Network implementation has seen tremendous growth and deployment in different types of networks. Compared to traditional networks it decouples the control logic from network layer devices and centralizes it for efficient traffic forwarding and flow management across the domain. This multilayered architecture has data forwarding devices at the bottom in the data plane, which is programmed by controllers in the control plane. The highlevel management plane interacts with the control plane to program the whole network and enforce different policies. The interaction among these planes is done through interfaces that work as communicationprogramming protocols. In this survey, we present a comprehensive study of these interface and programming protocols, which are primarily classified into southbound, northbound, and eastwestbound interfaces. This work first classifies each of them into subcategories and then presents a comprehensive comparative analysis. As the different interfaces have different properties, hence, the subclassification and their analysis are done using different properties. In addition, we also discuss the impact of different virtualization techniques, such as hypervisors, on interface protocols and interplane communication. More over specialized interfaces for emerging technologies such as the Internet of Things and wireless sensor networks are also presented. Finally, the paper highlights several short term and long term research challenges and open issues specific to the SDN interface protocols.