Multi-path Time Protocols

Abstract

Over the last few years, packet based networks have become the common transport for applications requiring clock synchronization. Classical time distribution protocols are run between a master clock and a slave clock using a single network path between the two clocks. A recently introduced approach called Slave Diversity uses multiple paths between a master-slave pair to reduce the effect of temporal congestion or errors in a specific path. The current paper applies the multi-path approach to the most widely-used packet based time protocols, PTP and NTP. We introduce extensions to the PTP and NTP standards called Multi-Path PTP (MPPTP) and Multi-Path NTP (MPNTP), respectively, and describe their application over various transport protocols. Our experimental evaluation shows that a large number of paths can be utilized when running the multi-path protocols over the internet, and thus that our multi-path approach can be effectively deployed over existing IP networks.