Introduction to time synchronization over Ethernet


Maciej Machnikowski


Nuts and Bolts

Session Type




The growth of fast LTE and the appearance of 5G networks results in rigorous requirements on timing in packet networks.
This session will introduce the basics of time synchronization in Ethernet networks. It starts with definitions and background of time sync, defines what we can synchronize, and why we need to.
Then it goes over the basics of frequency synchronization done on different levels - Physical layer explained based on SyncE and packet layer based on IEEE 1588 protocol.
The SyncE section explains the physical basics of the protocol, different operation modes of operation (QL-Disabled and QL-Enabled). It gives a brief overview of the ESMC messages that serve as a quality indicator.
The IEEE 1588 explains the basics of time synchronization using packet-based distribution. It describes how the timing information is recovered from the incoming data stream and what are the drawbacks of this method.
In the end, this talk compares different synchronization methods and explains where to use each of them to get the best results. It will also discuss the current gaps in the kernel APIs to enable better support for different synchronization methods and propose the solution to address them.