Prioritized admission control with load distribution over multiple controllers for scalable SDN-based mobile networks

Abstract

Software-defined networking (SDN) is a promising networking paradigm towards a centralized network control plane decoupled from the forwarding plane. Owing to its intrinsic separated architecture between the control and forwarding plane (OpenFlow switch specification 1.5.0. https://www.opennetworking.org/images/stories/downloads/sdn-resources/onf-specifications/openflow/openflow-switch-v1.5.0.noipr.pdf , 2014; Doria et al. in Forwarding and control element separation (ForCES) protocol specification. http://tools.ietf.org/html/rfc5810 ), SDN control plane is more sensitive to scalability concerns compared to traditional management systems (GPP TS 32.101. Telecommunication management; Principles and high level requirements (Release 14), 2017) because forwarding plane nodes no longer have the ability to make decisions of incoming traffics which means forwarding plane performance is highly dependent on the control plane’s response (Karakus and Durresi in Comput Netw 112: 279–293, 2016; Oktian et al. in Comput Netw 121: 100–111, 2017; Bianco et al. in Comput Commun 102:130–138, 2016). To solve the problem, SDN architectures employing multiple controllers have been proposed. However, when the load is concentrated on certain controllers, incoming requests to the controllers can be blocked while others are idle resulting in low efficiency overall. Especially, in mobile networks, this problem can become critical because blocking or delay of requests related to handover causes a severe quality of service degradation. This paper proposes a prioritized admission control scheme with load distribution over multiple controllers for scalable SDN-based mobile networks in which handover messages are admitted with high priority and load distribution is performed over multiple controllers to prevent blocking of handover messages. From the performance evaluation of the proposed scheme, the blocking probability of handover messages can be reduced and controller resources can be efficiently utilized without significant additional signaling load compared to conventional schemes.