Technology Update on IEEE 1588: The Second Edition of the High Precision Clock Synchronization Protocol

A high precision time base is important in many distributed systems. The Precision Time Protocol (PTP) specified in IEEE 1588 is able to synchronize networked clocks with an accuracy down to the nanosecond range. The mechanism combines high accuracy and fast convergence with low demand on clocks and on network and computing resources. A second generation of PTP has been developed and was approved in March 2008. It was published as standard document IEEE 1588 – 2008, also known as PTP version 2 (PTPv2). This new protocol offers some additional interesting features and improvements which open the door to new applications. The paper introduces the concept of IEEE 1588 synchronization mechanisms and explains then in more detail how PTP was enhanced, e.g. by Transparent Clock (TC), peer-to-peer delay measurement, unicast operation, pure layer 2 operation, enhanced accuracy, and extension mechanisms. Application examples show how these enablers are used by industry. Compatibility between PTP version 1 and version 2 is discussed. The semiconductor industry has created different solutions how PTP can be supported by hardware. The implementation options are outlined and discussed.