Virtualizing Packet-Processing Network Functions Over Heterogeneous OpenFlow Switches

The network function virtualization paradigm replaces dedicated hardware appliances with software running on virtual machines in commodity servers. However, to overcome performance and scalability issues on virtual network functions (VNFs) demanding intensive packet processing, we propose implementing these VNFs as programmable rules distributed among software-defined networking (SDN) switches. Our approach allows infrastructure providers to combine hardware-based and software-based SDN switches, exploring the tradeoff between the packet processing speed and instantiation flexibility. Our proposal includes a scalable mechanism, which decides the type and number of switches to meet network demand, along with a load balancing mechanism to distribute flows among switches, considering their singularities. We first evaluate our proposal in a small testbed with real equipment, confirming its effectiveness. Then, we evaluate our proposal with simulations to further investigate its scalability. Our results show that, even under high traffic loads, the joint operation of both mechanisms improves VNF capacity and saves virtualization resources.