Deliberately Congesting a Switch for Better Network Functions Performance

Traditional wisdom suggests maintaining minimal occupancy in the port queues of network devices to prevent packet delays or drops en route to their destination. In this paper, however, we explore the unconventional idea of deliberately congesting the queues of a network device to enhance the performance of a Network Function (NF) deployment. The key intuition behind this approach is to utilize the existing memory available in the switch queues to store packet payloads while their headers are processed on an external NF processor. We present two techniques for congesting a port on a switch: i) self-clocking packet recirculation, which recirculates packets within the switch to automatically achieve the correct queuing delay, and ii) a proportional controller using multicast forwarding, which adjusts the rate of packet forwarding based on the level of congestion. We evaluate our approaches both in simulations and a prototype.