Explicit Routing in Software-Defined Networking (ERSDN): Addressing Controller Scalability

Software-Defined Networking (SDN) promises a more flexible, automatable and programmable computer network. Software-Defined Networking separates the control from data plane. The control plane is placed in a centralized controller which network applications such as traffic engineering, QoS and firewalls reside. The centralize controller creates a scalability problem when large numbers of network events are processed in the control plane. Reducing the number of network events processed in the control plane and only processing required network events is critical in addressing the scalability concerns of SDN architecture. This paper addresses the scalability problem of controller by introducing Explicit Routing in SDN (ERSDN) which is a routing scheme used to reduce the number of network events processed by the control plane. This paper makes three contributions to research. First, it presents ERSDN a routing scheme used to select transit routers throughout the network at the edge routers. Second, it presents the design and implementation of ERSDN. Third, it evaluates the effect of ERSDN on SDN controller scalability in terms of the number of network events handled in the control plane. Finally, the results show that ERSDN is able to reduce the number of network events processed in the control plane by 430% when compared to traditional routing in SDN/Open flow network. ERSDN is a promising routing solution which can be used to address the controller scalability problem.