plication con- tinue to function correctly when the synchronization is lost? What are the existing timing methods, and how can they be reused or repurposed? What is the requirement for resiliency and failover protection? What form of transport is available, and can it carry time signals accurately? How will the end application "consume" the synchronization? Does it need some form of phys- ical signal and, if so, what is it? Will it take packets, and are those packets PTP? What version or profile of PTP is required? One axiom that the authors like to share when working with customers on timing networks is, "This is a timing problem; you need to design a timing solution." Meaning, it is not just a problem of transporting data packets from A to B, but one of transporting time. 3.6 Summary This chapter dealt with numerous synchronization concepts. First, you learned about the different network types, then the clock types and the operational state of the clocks. Next, you learned about sources of time, including various levels of oscillators and the many different GNSS systems. The chapter continued with a look at the evolution of various time distribution techniques, from TDM and physical methods to packet-based techniques and how they are related. Next, you learned about the timing distribution network and how information on the quality and traceability of the clock is maintained during transport. Chapter 5 goes into timing error, and clock noise performance, and "Chapter 12. Operating and Verifying Timing Solutions", covers the measurable characteristics of clocks and the testing and measurement of clock parameters. But the next step is into "Chapter 4. Standards Development Or- ganizations", that takes a small diversion and examines the major organizations that are setting the standards for both synchronization and mobile communications. Part II: SDOs, Clocks, and Timing Protocols Chapter 4. Standards Development Organizations This chapter provides brief introductions to various standards development organizations