Scalability analysis of the white-rabbit technology for cascade-chain networks

Due to an increase of timing requirements in many actual and future applications, improvements are needed in current synchronization protocols. New scenarios as the Internet of Things or the next generation of 5G Mobile telecommunication networks, where a large number of devices must be interconnected, will stand in need of a better synchronization accuracy and a highly scalable protocol. White Rabbit (WR) is a multi-collaborative open project aiming at the distribution of timing with sub-nanosecond accuracy to thousand of nodes connected within an Ethernet network. It is built as an extension of the Precision Time Protocol (PTP). In order to improve the PTP's accuracy, WR incorporates some enhancements such as a precise link delay model, fine delay phase measurement and clock syntonization over the physical layer. In this paper we focus on the scalability analysis of the WR solution with networks of more than 15 hops connected in a daisy-chain configuration, using the WR Light Embedded Node (WR-LEN) which includes the White Rabbit PTP Core Dual Port. The study evaluates the scalability of the WR extensions to PTPv2 for the achievement of ultra-accurate time transfer in networks with linear topology. The contribution results are relevant for applications where the scalability of the timing solution is a fundamental ingredient for addressing novel applications and markets.