Packet Subscriptions for Programmable ASICs

In this paper, we explore how programmable data planes can provide a higher-level of service to user applications via a new abstraction called packet subscriptions. Packet subscriptions generalize forwarding rules, and can be used to express both traditional routing and more esoteric, content-based approaches. We describe a compiler for packet subscriptions that uses a novel BDD-based algorithm to efficiently translate predicates into P4 tables that can support O(100K) expressions. Using our compiler, we've built a proof-of-concept pub/sub financial application for splitting market feeds (e.g., Nasdaq's ITCH protocol) with line-rate message processing, using the full switch bandwidth of 6.5Tbps.