Structured Characterization Methodology for Time Transfer in Packet-Switched Networks: A PTP-Unaware Case Study

Time transfer accuracy in packet-switched networks is fundamentally dictated by the infrastructure’s timing awareness, shifting from a jitter-limited bottleneck in precision time protocol (PTP)-unaware systems to an asymmetry- and hardware-limited regime in PTP-aware deployments. This article presents a structured, context-aware methodology designed to isolate and characterize the diverse network-induced impairments that degrade time-transfer accuracy under controlled conditions. This framework organizes the analysis across five aligned stages: 1) analytical infrastructure context; 2) traffic-dynamics modeling; 3) pre-experimental calibration; 4) controlled experimentation; and 5) an integrative analysis. As a primary validation of the framework’s baseline capabilities, the methodology is applied to a high-noise scenario in a controlled laboratory testbed: a static, PTP-unaware spine–leaf Ethernet fabric where packet delay variation (PDV) constitutes the dominant driver of offset evolution. The evaluation encompasses one server and three clients with distinct clock characteristics (quartz-based, high-precision oscillator, and high-precision with DPLL) across various traffic profiles and protocol settings. The experimental results reveal that the digital phase-locked loop (DPLL) client requires nearly 1 h to acquire lock, whereas the other oscillators lock within seconds; the optimal observation interval scales with variability (5 min under load, 15 min at 0 % load)—behaviors uncaptured by current ITU-T recommendations; and the DPLL client yields the lowest time offset despite its locking latency. By successfully isolating these baseline impairments, the method proves time-efficient and establishes a rigorous foundation for extending this statistical pipeline to PTP-aware infrastructures.