Both Big Data and Software-Defined Network have a significant impact in both academic and practical aspects. These two areas have been addressed separately, but both did not contribute to the same subset area of contribution. However, Big Data can greatly facilitate, improve, and have a great impact on Software Defined Network, and vice versa. In this paper, we show how SDN helps Big Data solve several issues regarding Big Data applications, including data processing in the data centers, data delivery and traffic monitoring. For Big Data, we also show how it can help SDN as well, including