Enabling Fast and Stable Service Mesh Communication via Piggyback Layer-7 Traffic Control on Programmable Switches

Service mesh has become an essential infrastructure for managing cloud-native microservices, widely adopted by major providers to streamline service orchestration and reduce operational overhead. A core component of service mesh architecture is the sidecar proxy, managing policy-based routing, Layer-7 load balancing, and related functions. Traditional per-pod distributed sidecar deployments route all inter-pod communication through local proxies, introducing substantial resource consumption and inefficiencies. Recent approaches advocate for centralized proxy deployments to offload compute-intensive modules to gateway nodes; however, this design introduces non-trivial traffic detours and exacerbates network congestion.To overcome these limitations, we propose PiggyCar, a novel service mesh communication system that piggybacks Layer-7 traffic control onto programmable network devices. In PiggyCar, resource-intensive tasks are offloaded to intermediary switches along inter-pod paths, enabling in-network execution of advanced network functions. PiggyCar incorporates a latency-aware offline planner for optimal network policy placement and a stability-oriented online scheduler that dynamically adapts to traffic fluctuations in real time. We prototype PiggyCar on a testbed comprising six servers and four programmable switches. Experimental results show that PiggyCar cuts latency by up to 97.2% compared to Canal, boosts throughput by up to 1.82× under high RPS conditions, and consistently delivers the lowest network jitter.