Albatross: A Containerized Cloud Gateway Platform with FPGA-accelerated Packet-level Load Balancing

Alibaba Cloud's centralized gateways relied heavily on high-capacity switching ASICs, but the abrupt halt of Tofino chip evolution in Jan 2023 forced us to seek alternatives that can meet the requirements of performance, supply-chain security, code reuse, and resource efficiency. After evaluating multiple options, we developed Albatross, our 3rd gen cloud gateway based on FPGA and x86 CPUs. Albatross delivers FPGA-based packet-level load balancing to the host CPUs to prevent CPU core overload, manages large reorder buffers under high-latency jitters (100μs) during complex cloud service processing, and resolves head-of-line (HOL) blocking from packet losses or software exceptions in CPUs. To avoid being overloaded by heavy hitters due to anomalies or attacks, it also implements a two-stage rate limiter for millions of tenants with only 2MB of FPGA memory. To maximize resource utilization, Albatross uses containerization to host multiple gateway instances and designs a BGP proxy to lessen the BGP peering overhead on uplink switches caused by high-density container deployments. After hundreds of man-months of development, a single Albatross node can process 80 120Mpps of cloud network traffic with an average latency of 20μs, reducing gateway and sandbox infra costs by 50%.