5 Minute Facts About Packet Timing You have a holdover requirement, and you need to select an oscillator from the choices presented to you by your timing equipment vendor. More stable oscillators are better, but they also cost more. You want to know which is the least expensive option that meets your requirement. However, the […]
What is gPTP?
Five-minute facts about packet timing gPTP is the name given to the IEEE 802.1AS profile of PTP. gPTP is only sort of a PTP profile. That is because gPTP is independently specified. In other words, rather than stating that it requires, forbids, and allows certain options defined in IEEE 1588, it specifies all these features […]
What happened at the last ISPCS PTP Plugfest
Five Minute Facts about Packet Timing After three years off for the pandemic, which felt like thirty, the ISPCS has been meeting in person again. In Vienna in 2022, London in 2023, and this year it will be in Tokyo in October. The ISPCS is the International Symposium on Precision Clock Synchronization. It’s a workshop […]
Problems with Unicast PTP
Five Minute Facts about Packet Timing When PTPv2 was defined the IEEE 1588 working group recognized that some networks, which could benefit from precise network timing, would not support multicast protocols. So, a unicast version of PTP was defined in IEEE 1588-2008. The ITU-T defined two PTP Profiles using unicast PTP, which have been used […]
When a Boundary Clock is the Grandmaster in a PTP network
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 […]
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 […]
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 […]