FDispatcher: Using Flow Director to Accelerate NFV Packet Dispatching

Packet dispatching forwards arrival traffic from the network interface card (NIC) to the virtual network functions (VNFs) in each server in network function vir-tualization (NFV) platforms and has been recognized as a fundamental problem. Traditionally, the dispatching has been CPU-intensive, while existing offloading approaches rely on expensive software-defined network (SDN) switches or Smart-NICs. Our paper proposes FDispatcher, an NFV framework that leverages the Flow Director (FDir) feature on the inexpensive off-the-shelf NICs, to bind flows with destination VNFs for CPU-bypassed packet dispatching. However, the number of bindings that FDir supports is far less than the flow concurrency that an NFV middlebox handles. We divide packet dispatching into FDir-assisted fast path and software-based slow path, and then enable fast-path flows monitoring, reduce FDir reconfiguration overhead, and eliminate potential heavy I/O during scaling. FDispatcher improves packet dispatching throughput by 1.6x~2.8x with a 38x driver efficiency and costs no more than 2 ms for load balancing during scaling.