Five Minute Facts About Packet Timing By Doug Arnold and Andreja Jarc A previous post discussed unicast PTP. Most PTP Profiles are based on multicast communication. However, PTP can operate using unicast. This is necessary in networks which don’t support multicast, or if there is a large number of PTP slaves, which would generate too […]
Hybrid Mode PTP: Mixed Multicast and Unicast
Five Minute Facts About Packet Timing By Doug Arnold. Quiet! Such is the lament of a PTP slave in a delay request – delay response PTP network. A slave port needs to receive Sync and Announce messages from a master port, and it needs to send Delay_Request messages and receive the corresponding Delay_Responses. If the […]
PTP in networks without timing support
Five Minute Facts About Packet Timing By Doug Arnold. In an earlier post I described how boundary clocks and transparent clocks correct for timing errors in the network between the PTP grandmaster and PTP slaves. But what do you do if you don’t have boundary clocks or transparent clocks? What if you have a bunch […]
Telecom Profile With Full On-Path Support
Five Minute Facts About Packet Timing By Doug Arnold. A while back I posted about the Telecom Profile for Frequency Synchronization, or ITU-T G.8265. In the view of the International Telecommunications Union (ITU), frequency was all they could promise with this profile since it assumed that there was no on-path support. In other words the […]
Time Synchronization Requirement for Synchrophasers
Five Minute Facts About Packet Timing By Doug Arnold. The IEEE Standard for Synchrophaser Measurements for Power Systems (IEEE C37.118.1 -2011) recommends that phase measurement equipment in power systems by synchronized to UTC to within 1 μs. That is fairly strict timing requirement for a system that deals with voltages and currents at the low frequencies […]
The PTP Telecom Profile for Frequency Synchronization
Five Minute Facts About Packet Timing By Doug Arnold. The Precision Time Protocol Telecom Profile for Frequency Synchronization was created by International Telecommunication Union, or ITU, for the transferring precise frequency through a packet switched network which does not have any support for PTP. Don’t let the name fool you though, you can transfer time […]
Unicast PTP
Five Minute Facts About Packet Timing By Doug Arnold. So far in this column we have talked about multicast PTP. Multicast is clearly critical to the working of the standard Best Master Clock Algorithm, since all the clocks need to discover who the possible master clocks in order to pick the best. However, some applications need unicast […]
Using SNMP to Manage Network Time Servers
By Andreja Jarc and Doug Arnold. The Simple Network Managment Protocol Most network connected devices support a number of management options including the Simple Network Management Protocol, or SNMP. SNMP is a network protocol which allows a single network management system to monitor a large number of devices on the network. Indeed this is one […]
The IEEE 1588 Default Profile
Five Minute Facts About Packet Timing By Doug Arnold. As we’ve seen in previous posts, PTP has many optional features, and often more than one way to do things. This is what gives PTP its awesome flexibility to cover so many different kinds of applications. There is however a dirty secret behind this power: PTP […]
NTP vs PTP: Network Timing Smackdown!
Five Minute Facts About Packet Timing By Doug Arnold. I get asked a lot of questions from customers about network timing technology. Some of them are challenging to answer. However, one that I get all the time that is easy to answer is this: “Do I want NTP or PTP?” It all comes down to […]