Expedited Eviction of Invalid Flow Entries for SDN-Based EPC Networks

Abstract

The explosive growth in mobile data traffic requires a significant redesign of the existing 3GPP Evolved Packet Core (EPC) network’s data and control planes. As a new type of EPC architecture, Software defined Networking (SDN) has been used in a large number of scenarios due to the fact that it realizes flexible and efficient control of the network, and promotes the evolution of the network to a programmable and scalable direction. However, the transition of traditional networking model to SDN architectures poses scalability issues because of the limitation of Ternary Content Addressable Memory (TCAM) in size. Facing the traffic explosion on future networks with resource-constrained architectures, TCAM storage space is not enough to bear so much traffic flows so that it not only causes performance degradation in data transmission but also results in scalability and cost-efficiency issues. In this paper, we propose an early eviction strategy to evict the invalid flow entries simper and faster to address this issue, based on detecting the message of timeout and the disconnect signaling of Stream Control Transmission Protocol (SCTP). The behavior of detection is achieved by adding a specific SDN rule set with a transparent layer in between the controller and switches, referred to as a SCTP detector. Different with the original solutions, the SCTP detector can delete invalid flow entries in time according to the layer of the transmission disconnection instead of relying on the timeout mechanism. We will also demonstrate the superiority of our proposed solution in reducing the flow entries occupancy and improving the table-miss rate through a series of simulation results.