FHA: Flow-level High Availability on Programmable Network Hardware for Cloud Provider

With the advancement of data center intelligence, more flow states are being managed by programmable switches and DPUs to enhance efficiency and reduce overhead. However, in practical deployment, they face the challenge of achieving high availability. This is primarily due to the large flow tables in smart hardware, which require significant hardware and network overhead for synchronization between devices. On the other hand, the flow states often change, making rapid synchronization with the hardware another challenge. In this paper, we design a synchronization system, FHA, between smart network devices, utilizing both the control plane and the data plane to solve the challenge of rapid synchronization. Additionally, we have designed the RangeSync algorithm, which greatly reduces the overhead of synchronizing flow tables between systems. We implemented a preliminary prototype on the AMD Pensando DPU. In our evaluation, our data plane synchronization achieved a latency of 6μs. For the control plane channel, compared to the baseline, synchronization resulted in an 83.3% reduction in latency and a 66.7% decrease in overhead when synchronizing 12 million flow states.