P4+NFV: Optimal offloading from P4 switches to NFV for diverse traffic streams

Software-defined Networking (SDN) is making its mark in the operator networks. The latest generation of SDN switches supporting paradigms such as P4, are paving the way for complete data plane programmability. Though P4 switches enable some newer applications, they do not provide the same agility and scalability offered through fully programmable softwarized data planes of Virtual Network Functions (VNFs). This paper argues that to achieve substantial performance benefits, an operator can take advantage of deploying P4 switches alongside VNFs. The idea is to use the P4 switch as a default packet handler, whereas traffic can be offloaded to an off-site VNF when queues at the switch start to build. To this end, this paper first models the queuing behavior of a networked system with a P4 switch and a VNF to determine the queuing delay induced by such a hybrid architecture. While doing so, the paper considers two different cases of homogeneous and heterogeneous traffic patterns. Subsequently, the paper proposes algorithms for finding optimal traffic offloading, leading to overall delay minimization. The paper showcases significant performance gains of optimally offloading traffic from a P4 switch to a VNF amidst changes in disparate traffic and network parameters through simulations and analytical results. For instance, at moderate loads of homogeneous traffic, optimal offloading yields performance gains of up to 76.44% over a scenario where a P4 switch handles all the packets. For heterogeneous traffic patterns, the results show that the dominant flow's workload and average packet size can significantly impact the offloading performance. © 2024 Elsevier B.V.