Architecture of an embedded time gateway between PTP and SNTP

This paper deals with time synchronization in mixed network infrastructures for automation of industrial and electric plants, where old devices, which retrieve time information with the well-known NTP, must coexist with new IEEE1588 PTP compliant devices. Since PTP and NTP use very different time representations and synchronization strategies, an easy integration is quite difficult and requires additional hardware. The paper describes a transparent Time Gateway that is able to interface SNTP devices with a PTP synchronization domain (PTP devices and PTP switches). The Time Gateway has been realized with an embedded system based on an FPGA with a soft processor and an open source operating system. Preliminary experimental results show the feasibility of the proposed architecture, even if some improvements may be needed to match the time synchronization accuracy required by the legacy SNTP devices.