5 Minute Facts About Packet Timing I recently received some questions about Boundary Clocks (BCs) becoming Grandmasters (GMs) from a blog reader sent to my email. Yes, I really answer them. It was especially interesting because we spent a lot of time discussing stepsRemoved and BC/GMs at a recent meeting of the Network Synchronization and […]
A Step Toward a More Inclusive Terminology for PTP
Five Minute Facts about Packet Timing The IEEE Standards Association will soon published IEEE 1588g-2022, an amendment to IEEE 1588-2019. The amendment recommends optional alternative terms for master and slave. The terms selected are: The obvious concern is the one about the insensitivity of using the institution of slavery as a technical analogy. Another concern […]
IEEE 1952: the new standards project for resilient PNT
Five-minute facts about packet timing If you’ve been paying attention, and I know you have, there has been a lot of discussion lately about the fact that the critical infrastructure of the world is dependent on GNSS for position, navigation, and timing (PNT). I’m talking about everything that differentiates us from wild animals: power, communications, […]
Genlock in a networked world
Five-minute facts about packet timing Once upon a time there was an industry that needed data sharing and time synchronization among devices that were spatially disbursed. So, the industry developed standards for data transfer and timing signals that each device could interface to, and everything worked. But the technical professionals in the industry did not […]
BMCA Deep Dive: Part 2
Five-minute facts about packet timing This is part 2 of a two-part description of the Best Master Clock Algorithm (BMCA). In Part 1 we listed the information that is considered in the BMCA and what the priorities are amongst those quantities. You can think of this information as the clock credentials. If you missed part […]
BMCA deep dive: part 1
Five-minute facts about packet timing I previously posted about the Best Master Clock Algorithm or BMCA. Nevertheless, this aspect of the Precision Time Protocol (PTP) continues to stimulate questions from equipment designers and network operators. So, I will attempt to describe it in more detail, which will be spread over two posts. In this post […]
Network Time Security (NTS): Updated security for NTP
Five-minute facts about packet timingNetwork Time Protocol version 4 (RFC 5905) is a spectacularly successful network time transfer protocol. It can be found in almost every IP network. Often NTP messages will traverse leased lines or the “public internet”. Therefore, it is especially important that an NTP client can determine that the NTP server is […]
Implementing PRP devices and networks
5 minute facts about packet timing In a previous post I talked about the new redundant networking protocols High Availability Seamless Redundancy (HSR) and Parallel Redundancy Protocol (PRP). These protocols are defined in the IEC 62439-3 standard. Today I want to talk in more detail about PRP devices and networks. Recall that a PRP network […]
The Root of All Timing: Understanding root delay and root dispersion in NTP
Five Minute Facts About Packet Timing If you examine an NTP packet you will see the fields root delay and root dispersion. See the diagram from RFC 5905 in Figure 1 bellow, which defines NTP version 4, the current version. You might ask what is with all this “root” stuff? Root in this case refers […]
Unicast Master Port Selection in PTP: When should a slave port swipe right
Five Minute Facts About Packet Timing In multicast PTP a slave port need only subscribe to the PTP multicast addresses and timing will come to it. However, in unicast PTP a slave port has to reach out to the master port it wants time from with PTP message requests. It is more of a client-server […]