A survey on issues of concern in Software Defined Networks

Software Defined Network (SDN) is a network architecture in which the network traffic may be operated and managed dynamically according to users´ requirements and demands, thereby making SDN feasible for all networking domains. This is possible in SDN because the data and control planes are detached from one another. The control of packet forwarding is set apart from the forwarding elements and is the performed by a programmable software component, the controller. The forwarding elements such as switches function only as packet carrying devices. This architecture provides open interfaces for communication between the controller and the forwarding hardware as well as the controller and the network applications. OpenFlow (OF) is regarded as a standardized protocol for SDN which provides interfaces for communication among the controller and forwarding elements. The controller programs the data plane through these interfaces, whereas network applications are developed using open interfaces for communication among the controller and the applications. Therefore, the controller through programmatic control is able to manage the network devices as specified by these custom-built network applications. SDN is the latest network architecture and OpenFlow protocol is still in its initial stage. So, in the present scenario few issues exist in SDN as well as in the OpenFlow protocol. This paper focuses on most of the issues that exists in SDNs and OpenFlow.