Indian Standard Time Dissemination Using Precision Time Protocol: Toward Resilient Time Synchronization Using Optical Fibers for Critical Infrastructure in India

National time dissemination using terrestrial ethernet and optical fiber cables is an alternative to satellite-based systems and provides redundancy to reliable time services for critical infrastructure in the country. Precision time protocol based on IEEE 1588 standards using such cables and fibers can provide sub-microsecond time synchronization between a provider and the client. The method employs hardware time stamping, dedicated traffic-free fiber links, and PTP-aware network elements. We present a proof of concept experiment for the distribution of Indian standard time using the IEEE protocol in a laboratory and the effect of introducing a PTP-supported switch on the distribution performance. Further, we report on the observed synchronization when an underground dark telecom optical fiber lying outside the laboratory in the central Delhi region is used as the medium of communication. The short-term one-second pulse–pulse jitter is found to be around 2.5 ns without any drift during the measurement period.