 transport network. This in- volves the use of devices with outstanding holdover performance, autonomous sources of time (such as atomic clocks), and clever network design to provide redundancy in the timing signal. The final aspect to consider is the security of the timing signal, both in the PTP message stream it- self and within the transport links. This is covered in prongs A and B of Annex P of IEEE 1588- 2019 and includes the ability to use MACsec in the links without sacrificing phase/time accuracy. Chapter 12 covers the final topics when implementing a timing solution, which includes hardware design, procurement, acceptance testing, assurance, and monitoring as well as troubleshooting and field testing. Chapter 12. Operating and Verifying Timing Solutions In this chapter, you will learn the following: Hardware and software solution requirements: Describes the components that make up a PTP-aware device and the principles underlying the design of an accurate clock. Writing a request for proposal: Gives hints and tricks about writing an effective RFP to help properly select network elements for a network-based timing solution. Testing timing: Introduces the equipment, methods, and test cases involved when testing both the behavior and performance of either a transport network or a standalone clock. Automation and assurance: Covers aspects of configuring and managing the timing network using automation tools. It begins with the Simple Network Management Protocol (SNMP) be- fore moving on to more modern approaches with NETCONF/YANG. Troubleshooting and field testing: Covers aspects such as common problems that engineers encounter, troubleshooting, clock accuracy monitoring, field testing, and extensive information on global navigation satellite system (GNSS) receiver performance. The chapters up to this point have covered many of the theoretical aspects of deploying a timing solution, the requirements and design for a mobile deployment, and the ITU-T recommendations supporting all aspects of building a timing 