Network Functions With Dynamic State Management on Programmable Switches

Recent popular programmable switches provide programmability in packet processing at the line rate, promising to host various Network Functions (NFs). However, the limitations on the switch programmability make it unable to manage runtime dynamic NF states. In the status quo, on-switch NFs rely on the network controller for dynamic state management, suffering from high first-packet latency. This paper proposes DNF, a hardware-software co-design system for dynamic state management of network functions on programmable switches. DNF designs a dynamic State Table on the switch, which provides <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opportunistic</i> service to NF flows and sets up <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fallback</i> NFs on the server to handle flows that fail on the switch. DNF proposes a state pre-computation and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">runtime-binding</i> method for per-flow state initialization, which avoids a flow’s runtime interaction with the controller and the consequent latency. DNF devises a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">state replacement</i> method, which periodically swaps hot flows into the switch. It could maximize the switch resource utilization and the throughput. We prototype DNF on P4 switches, implement six representative NFs, and compare DNF with state-of-the-art solutions. Our experiments show DNF reduces the first-packet latency by up to 98% compared with the controller-assisted architecture and improves the system throughput by up to 4.87 times compared with the software solution.