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 … [Continue reading]
Implementing PRP devices and networks
5 minute facts about packet timingIn 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. … [Continue reading]
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 … [Continue reading]
Unicast Master Port Selection in PTP: When should a slave port swipe right
Five Minute Facts About Packet TimingIn 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 … [Continue reading]
What’s new in IEEE 1588-2019: L1 Sync
Five Minute Facts About Packet Timing Time to play what's new in IEEE 1588-2019, the game where everyone wins new PTP features. L1 Sync is short for physical layer frequency synchronization. Recall that frequency sync is also referred to … [Continue reading]
What’s in IEEE 1588-2019: DIY PTP Port States
Five Minute Facts About Packet TimingIn this installment of What’s in IEEE 1588-2019 we look at the exciting and dangerous world of manual port state configuration1. The Best Master Clock Algorithm leaving you uninspired? No longer a problem, you … [Continue reading]
PTP Auto Mode
Five Minute Facts About Packet Timing By Andreja Jarc. In this post I would like to introduce a method which can be deployed in versatile PTP networks, professional media, power or any other timing network. Basically, it is a method which … [Continue reading]
The PTP AUTHENTICATION TLV
Five Minute Facts About Packet Timing This is the next installment in our series: what is in the 2019 edition of IEEE 1588. Recently, I posted a discussion about GNSS spoofing, and what to do about it. However, the radio interface is not the only … [Continue reading]
GNSS Spoofing and how to mitigate it
Five Minute Facts About Packet Timing In a previous post I talked about GNSS jamming and how to mitigate it. Today I will discuss GNSS spoofing. Once again GNSS means Global Navisgation Satellite System, which includes not only GPS, but similar … [Continue reading]
GNSS jamming and how to mitigate it
Five Minute Facts About Packet Timing This post discusses GNSS jamming, for a discusstion of GNSS Spoofing see the follow up post. Before a timeserver transmits messages with timing information it usually gets that information from a GNSS … [Continue reading]