Challenges and solutions to consistent data plane update in software defined networks

Software Defined Networking (SDN) has emerged as a promising paradigm to make network management easier while supporting various applications requiring different guarantees in terms of performance, availability and correctness. In essence, SDN decouples the control and data planes such that a logically centralized SDN controller finds the paths based on given requirements, and then accordingly installs the necessary forwarding rules on the distributed SDN switches, which are simple forwarding devices. Due to various reasons such as congestions, failures or policy changes in the network, the SDN controller needs to find new paths and shift the traffic from the original paths to the new paths. However, during this transition, numerous time consuming steps need to be performed such as updating nodes on the new paths. If not carefully coordinated, these updating steps may cause loops, black-holes, and performance degradations. In this paper, we provide a detailed survey of the existing techniques that try to consistently update the new state of the data plane. We also discuss open issues and future challenges.