SDN Interfaces: Protocols, Taxonomy and Challenges

The ever-increasing demands of Internet services like video on demand, big data applications, IoE and multi-tenant data centers have compelled the network industry to change its conventional non-evolving network architecture. Software Defined Network (SDN) has emerged as a promising network architecture which provides necessary abstractions and novel APIs to facilitate network innovations and simplifies network resource management by breaking the conventional network into multiple planes. All these SDN planes interact through open interfaces or APIs which are commonly categorized into southbound, northbound and west/eastbound interfaces. In this manuscript, we have identified and emphasized various communication protocols used at south and northbound interfaces. We have provided a taxonomy of south and northbound communication protocols based on their dependence, capabilities and properties. The pros and cons associated with each communication mechanism are highlighted and the numerous research challenges and open issues involved at these two interfaces are elucidated. In addition to it, we have proposed the necessary abstractions and extensions required in communication protocols at these two interfaces to simplify real-time monitoring and virtualization in next generation networks.