Session

Almost a quarter of the world-wide consumer Internet traffic is pushed through mobile networks (roughly 75 exabytes per month in 2022 [1]). Such traffic creates a demand for high data rates and continuous development of telecommunications standards. High traffic requires not only efficient bandwidth utilization but also a good synchronization between wired components of 5G/6G network. Well-known PTP (Precision Time Protocol [2]) with its sub-microsecond synchronization needs to be improved even more. To achieve sub-nanosecond synchronization, it needs to be coupled with Synchronous Ethernet (e.g., White Rabbit Project [3][4]).

Synchronous Ethernet (SyncE) is a technology that allows transport clock signal through the Ethernet physical layer. This prevents the clock skew and clock jitter between adjacent network nodes. SyncE signaling protocol itself is defined by a series of ITU-T recommendations (ITU-T Rec. G.8261, G.8262, G.8264).

The presentation aims to describe the need of having frequency synchronization and its role when coupled with PTP in 5G/6G networks [5]. Its focus is SyncE signaling protocol implemented by Linux open-source project synce4l [6]. The application can work either as a source for frequency synchronization hierarchy (leader) or as on the node synchronizing to it (follower). The presentation shows the synce4l project, focusing mainly on the features, requirements (both in software and hardware), and configuration in a real network. Finally, it describes how synce4l corresponds with the currently discussed new DPLL (Digital Phase Locked Loop) subsystem [7] in the Linux kernel and user-space networking community.

[1] https://twiki.cern.ch/twiki/pub/HEPIX/TechwatchNetwork/HtwNetworkDocuments/white-paper-c11-741490.pdf [2] https://en.wikipedia.org/wiki/Precision_Time_Protocol [3] https://white-rabbit.web.cern.ch/ [4] https://ohwr.org/projects/white-rabbit/wiki/WRpublications [5] https://moniem-tech.com/2023/02/20/time-synchronization-is-critical-in-5g-open-ran-network/ [6] https://github.com/intel/synce4l [7] https://lore.kernel.org/netdev/20230824213132.827338-1-vadim.fedorenko@linux.dev/#r