SwitchNIC: An Hybrid Architecture for Network Functions with Fast and Consistent Shared State

To support high-performance network functions, recent work has explored hybrid architectures that combine the flexibility of general-purpose processors with the performance of the PISA switch architecture. These designs partition code and state between switch platforms and general-purpose servers in pursuit of a ''best of both worlds'' design. However, integrating two separate platforms leads to the age-old challenge of ensuring high throughput and low latency while keeping distributed state consistent. We propose a new, tightly-coupled architecture called SwitchNIC that guarantees consistent state between switch and general-purpose processor, while offering 99-th percentile packet latency of 6 μs. The key to SwitchNIC's performance is a novel, ''on-path'' state replication protocol, with latency further tightened by implementing general-purpose processing on locally-integrated ARM cores. We prototype SwitchNIC by deploying its state replication algorithms on a Tofino switch with Ethernet-attached ARM-based SmartNICs. SwitchNIC achieves up to 5.2x better energy efficiency and 6.4x better processing latency than server-based systems, none of which completely and correctly support shared state between platforms.