The Precision Time Protocol (PTP) according to IEEE 1588 and its variants are increasingly being used as the basis for achieving accurate media clock distribution and synchronization in media networks. This article introduces the principles of PTP with a view towards media clock synchronization, and gives an overview of requirements for media clock distribution in a network. We show how PTP can be harnessed for reconstructing media clocks locally in each network node in such a way that those requirements can be met. We discuss different strategies for clock synthesis and distribution, their application area, and the impact on the implementation of a node. We finally discuss two existing media network frameworks (AVB and RAVENNA) which both utilize PTP for media clock synchronization, and analyze the commonalities and differences between them.
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