In this paper, we explore how a programmable forwarding plane offered by a new breed of network switches might naturally accelerate consensus protocols, specifically focusing on Paxos. The performance of consensus protocols has long been a concern. By implementing Paxos in the forwarding plane, we are able to significantly increase throughput and reduce latency. Our P4-based implementation running on an ASIC in isolation can process over 2.5 billion consensus messages per second, a four orders of magnitude improvement in throughput over a widely-used software implementation. This effectively removes consensus as a bottleneck for distributed applications in data centers. Beyond sheer performance, our approach offers several other important benefits: it readily lends itself to formal verification; it does not rely on any additional network hardware; and as a full Paxos implementation, it makes only very weak assumptions about the network.

Programmable network hardware can run services traditionally deployed on servers, resulting in orders-of-magnitude improvements in performance. Yet, despite these performance improvements, network operators remain skeptical of in-network computing. The conventional wisdom is that the operational costs from increased power consumption outweigh any performance benefits. Unless in-network computing can justify its costs, it will be disregarded as yet another academic exercise.

Traditionally, computer storage has been separated into a hierarchy based on response time, volatility, and cost of media. This tiering is undergoing a significant upheaval as a new breed of memory technologies, termed Storage Class Memories (SCM), now make it feasible to replace several tiers of the hierarchy with a single, cost-effective, uniform type of memory/storage. To make large-scale SCM deployments practical, however, memory system designers will first need to solve the problem of how to guard against unavoidable storage wear-out and failures-problems traditionally absent from "main memory" and handled by software at leisurely timescales in the domain of storage. In this paper, we propose a novel approach to providing fault tolerance in SCM-based main memory. Our key insight is to treat memory as a distributed storage system and rely on data replication and a consensus protocol to keep the replicas consistent. Separate memory instances store replicated copies of the data, and we use a programmable network interconnect to provide fast consensus between the memory instances. Our initial experiments using software memory controller emulation demonstrate reasonable overhead over local memory reads and show great promise as scalable main memory.