  Consensus protocols are the foundation for building many fault-tolerant
distributed systems and services. This paper posits that there are significant
performance benefits to be gained by offering consensus as a network service
(CAANS). CAANS leverages recent advances in commodity networking hardware
design and programmability to implement consensus protocol logic in network
devices. CAANS provides a complete Paxos protocol, is a drop-in replacement for
software-based implementations of Paxos, makes no restrictions on network
topologies, and is implemented in a higher-level, data-plane programming
language, allowing for portability across a range of target devices. At the
same time, CAANS significantly increases throughput and reduces latency for
consensus operations. Consensus logic executing in hardware can transmit
consensus messages at line speed, with latency only slightly higher than simply
forwarding packets.
