US Patent 11258876 Distributed flow processing and flow cache

The techniques disclosed herein improve the efficiency, reliability and scalability of flow processing systems by providing a multi-tier flow cache structure that can reduce the size of a flow table and also reduce replicated flow sets. In some configurations, a system can partition a flow space across workers and replicate the flows within a partition to a set of workers. In some configurations, a flow cache structure can include three tiers: (1) a scalable flow processing layer for executing the actions and transformations of a flow, (2) a flow state management layer for managing distributed flow state decisions, and (3) a flow decider layer for identifying actions and transformations needs to be executed on each packet of a flow. Flow replications allow other workers to pick up flows allocated to a particular worker that is taken offline in the event of a crash or update.