How Do Synchronous Ethernet And Precision Time Protocol Work? Part 2: Precision Time Protocol (PTP) by Per Lembre, Director of Product Marketing, Xelerated
Precision time protocol (PTP), defined in IEEE-1588, is the dominating packet method for precision time distribution. Currently, there are two versions of PTP technology available. The PTPv1, released in 2002, defines a hierarchical chain of master-slave relationships. While this served the target application well, it faced scaling challenges for WAN applications and carrier infrastructure. In PTPv1, synchronization quality degrades as new layers are introduced and more members are added to the hierarchy. This was why a major revision, PTPv2 was developed and approved in March 2008.
Developed to achieve higher accuracy, PTPv2 introduces a couple of new architecture models and message formats. In addition, the standard allows for profile definitions for its usage in specific applications. One example is IEEE 802.1AS, which focuses on how to apply PTP in audio -video broadcast home networks. Profiles allow optional features to be added, including fault tolerance and security. The profile may also specify architecture implementation by limiting the options available.
