PTP Implementation and Troubleshooting

The synchronization of data networks has been of critical importance from the very beginning of the digitization of network communications. Mobile cellular networks, satellites, television head-end services and Optical Fibre Communications Transports have all depended upon good synchronization. As data rates and distances increase the precision of synchronization must be improved. Also as we link different technologies together and group them into larger and more complex networks synchronization across networks become important too.

When Internet services started carrying time Network Time Protocol (NTP) provided and mechanism which allowed time to be carried in a uniform way through the Internet over asynchronous as well as synchronous networks. This enabled accuracy of timing to be improved across the world with precision of a few milliseconds. While this was an important step and provided accurate time synchronization for most business applications, with increases in technology speed and many real-time applications coming online greater precision has become necessary. This is particularly important when network speed start to reach 10 Gbit/s and above, when trading applications need to achieve billions of transactions per second or UHD video applications need to synchronize individual lines or pixels of a picture.

Once we used to provide timing trunks to each individual network component on a point to point basis. This is complex and very expensive as network now stretch across the world. Today we need to carry a master clock signal through multiple network components which may each introduce delay and recover and further relay the signal compensating for the inevitable delays along the way.

IEEE 1588, Precision Time Protocol (PTP) was designed to achieve precision timing and to meet the new set of modern synchronization needs. The difference between PTPv1 and PTPv2 will be studied. Hands-on exercises will focus on IEEE Std. 1588-2008, PTP version 2, its configuration on systems and its management using RFC 8173 PTP version 2 MIB. Hands-on exercises will include configuring Master and slave clocks, running PTP over Multicast and unicast operation and analysis of captured PTP traffic in class and from live systems where available.

This course is designed to provide a good understanding of the problems in providing accurate time synchronization, describe the evolution of PTP from the roots of NTP and compare the functions of NTP with PTP versions 1 and the latest version 2 implementations.

In-class exercises will be based upon laptop software implementations of PTPd open source code. Students will configure the range of different kinds of PTP clocks - Grandmaster (GM),  Boundary Clock (BC) and Ordinary Clocks (OC). The way clocks are selected in PTP and NTP will be compared and the protocol exchanges analysed using WireShark protocol analysers. Configurations that allow the compensation for delays will be studied and the integration of NTP and PTP networks considered. Configurations will include delivery of timing using Multicast services and also unicast services.

In real operational networks failures occur from time to time and this can lead to drift and inaccuracy of time. The course will teach how to detect and troubleshoot problems, consider how to correct the inaccuracies and recover from these situations in a controlled manner. Students will monitor how the best Master clock is selected from a group by attaching their configured Master, and Slave clocks to a common network by analysing the resultant traffic using WireShark and monitoring timing performance.

Multicast video running over Real-time Transport Protocol (RTP) is used in modern IPTV Head-ends. Generated IPTV traffic will be used to demonstrate the carriage of time clocks in such environments and hands-on exercises will be used to identify the accuracy of timing on both lightly loaded and heavily loaded segments. The impact of relaying streams though switches with varying loading and thus varying delay will be studied hands-on and the performance of PTP modules monitored. The impact of failing switches and re-routing traffic will be studied and methods of detecting and correct problems studied.

This course is intended for engineers, service designers, developers, systems engineers and troubleshooting technicians involved in the development and support for IPTV Head-ends, 4G and 5G Mobile services, optical telecommunications and satellite systems that require precise timing systems.  Hands-on exercises will use Windows based PCs or laptops deploying Virtual Machine environments to build different kinds of PTP clocks. They will use GPS and other Master clock systems in order to compare the accuracy and effectiveness of different kinds of PTP clocks. They will learn how to configure Master, Boundary and Slave clocks in Hands-on class exercises,  as well as using an Internet Simulator to test performance under controlled fault conditions. Exercises will be run over an in class LANs to test performance and troubleshoot typical faults. Attendees will be given an opportunity to connect their own Windows 10 laptop in order to run the hands-on exercises and build their own clock systems.