Tiered gPTP: A Simulative Study on Balancing Time-Sync Accuracy and Coverage with Time Source Replication

Deterministic Networking (DetNet) is designed for real-time applications in wide-area networks requiring time synchronization within 1 μs. However, gPTP has the problem of decreasing accuracy as the number of hops between a reference clock and its client increases. To address this problem, we might deploy many Grandmaster Clocks (GMCs). However, its financial cost is too high. To solve these problems, we propose Tiered gPTP, in which nodes synchronized by HUYGENS act as reference clocks, based on the stratum structure defined in the Network Time Protocol (NTP). We have implemented a Tiered gPTP system in OMNet++ and conducted simulation analyses to demonstrate its effectiveness. The evaluation results show that the Tiered gPTP system achieves time synchronization within 1 μs at a lower financial cost than deploying multiple GMCs.