Software-Defined Networking has been gaining increasing attention in both research and industry communities. Separating the control and data planes has brought many advantages such as greater control plane programmability, more vendor independence, possibility of network virtualization, and lower operational expenses. SDN deployments are possible in a variety of contexts: Enterprise networks, Datacenter networks, and WANs. However, SDN raises several concerns for WANs including performance limitations due to the larger propagation delays, the increased controller work load due to a larger
number of network elements, and concerns about performance impacts of the controller placement.
This study attempts to address some of these issues by examining the effects of using source routing as an alternative to traditional distributed routing in SDN-based WANs. Our simulations and analysis show that source routing can bring significant gains in SDN performance in WANs, improve network scalability, and reduce network performance sensitivity to controller placement.