OmniPath Ping: Active Network Measurement in the Era of Packet Spraying

Ping and Traceroute constitute the fundamental toolkit for network monitoring. Built upon these primitives, initial active probing systems focus on achieving sufficient coverage of switches and links. To further diagnose subtle failures (e.g., misconfigurations) affecting specific service flows, recent systems have proposed service tracing to measure their connectivity and performance. These systems operate effectively under the widely adopted flow-level LB scheme (i.e., ECMP), which binds each flow to a deterministic path. However, the paradigm shift towards packet-level LB (e.g., packet spraying) in next-generation networks invalidates this foundation. By dispersing packets of a single flow across multiple paths, packet spraying causes traditional primitives to suffer from path ambiguity in failure localization and incurs prohibitive overhead for full path coverage. In this paper, we propose OmniPath Ping (OPP), the first diagnostic primitive designed for service tracing under packet spraying. OPP overcomes these challenges through a switch-host co-design featuring two key techniques: (1) an in-network OmniPath cache that captures per-hop telemetry to resolve path ambiguity; and (2) in-network duplication and deduplication mechanisms that enable full path coverage with zero redundancy. To further ensure scalability for network-wide service tracing, OPP incorporates (3) a topology-aware concurrency control mechanism to balance OmniPath cache SRAM usage and probe timeliness. Extensive results demonstrate that OPP achieves 10 ms-level service tracing with full path coverage at minimal host and network overhead, requiring only 181 KB of switch SRAM.