LAUSR

The transition from serial digital interface (SDI) to the All-IP studio has been happening more frequently, with numerous broadcasting facilities partly, or even exclusively, relying on this new technology. Accurate and reliable synchronization is a mandatory requirement for every broadcasting studio. Consequently, packet-based time transfer over Ethernet evolved into a crucial building block. The Precision Time Protocol (PTP) has proved time and again that it can deliver the required accuracy of less than $1~\mu \text{s}$ regardless of the size and topology of the underlying network. Its inherent fault tolerance is limited and thus insufficient to fulfill the stringent requirements of the broadcasting industry in that respect. Thus, it has to be extended to a highly robust and resilient time transfer technology by applying a series of enhancements. This paper presents various ways of significantly improving the resilience of PTP including an in-depth analysis of failures caused by malfunctioning or misconfigured devices as well as malicious attacks. The latter should be investigated independently because PTP itself is vulnerable to such attacks. Countermeasures for all major fault conditions are presented together with their potential impacts on time transfer. Realworld examples with typical failure conditions and their effects on accuracy, both locally and systemwide, are given. Methods on how to prevent these failures altogether or at least detect them reliably thus being able to issue adequate countermeasures without delay are discussed as well. The paper concludes by presenting ways the broadcasting industry can benefit from these new features efficiently and quickly .