FEPS: Flow Entries Preprocessing Scheme for Software Defined Networks

Software Defined Networking (SDN) is a nextgeneration networking paradigm where the forwarding and control planes are decoupled. This decoupling enables intent-based networking. The two planes communicate using the OpenFlow protocol, which all networking components in the forwarding plane must support. Since the control plane is separated from the OpenFlow switches, all intelligent decision-making, including the management of the routing table (referred to as the flow table), is handled by the control plane. The flow table used in SDN is designed using Ternary Content Addressable Memory (TCAM). However, TCAM is power-hungry and storage-inefficient, allowing it to accommodate only around 1,500 to 3,000 entries in the flow table. This limitation makes the SDN flow table vulnerable to flow table attacks. In this research study, a Flow Entries Preprocessing Scheme (FEPS) is proposed to preprocess flow entries, eliminate redundant ones, and free up the flow entries storage space. FEPS utilizes a Radix Trie data structure for this preprocessing, which is also known as a compression trie. The evaluation of FEPS is conducted in three different topological scenarios, achieving a compression ratio of up to $\mathbf{7 8. 8 1 \%}$. Since FEPS is a software module, the overhead of adding any hardware to the OpenFlow switch is eliminated. The efficacy of FEPS surpasses the evaluation metrics of other studies.