Implementing a recirculation‑based selective forwarding unit using P4

Modern video conference applications rely on Selective Forwarding Units (SFU) to replicate packet traffic between participants. Traditional SFUs commonly operate in user space and as such are required to move packets to and from it so they can copy them. These operations have a significant negative impact on latency. Switches with programmable dataplanes offer a solution to this problem enabling SFUs to run directly on switches and thus not to incur such costs. Using P4, an open-source programing language for switches, specifically its recirculation feature, in which packets can reenter a switch pipeline instead of being transmitted, a more efficient SFU was developed. After its development, it was compared with a Python-based SFU implementation running in user space on a Linux host, instead of on a switch, similarly to traditional SFUs. Even in simulated hardware, the P4-Based SFU outperformed its counterpart by demonstrating lower latency, increased stability and reduced packet loss. The results highlight the potential of programmable dataplanes for the development of high performance SFUs.