Products

Microprocessors, GPS-linked Clocks,

Boundary Clocks, NIC cards,

Protocol Stacks, RF Instrumentation,

Aircraft Flight Monitoring Instruments, etc

Typical Applications

Industrial automation, T&M, Military,

Power Generation and Distribution,

Consumer Electronics, telecommunications, etc

Some Common Features

  • Mappings to UDP/IP v4&6, Ethernet (direct mapping), DeviceNetTM, PROFINET, ControlNetTM

  • Optional unicast messaging (in addition to multicast)

  • Formal mechanisms for message extensions (using TLV)

  • PTP profiles

  • Transparent clocks

  • Configuration options

  • Synchronization accuracies better than 1 ns

  • Security (experimental specification only)

    • Covered very briefly in this tutorial
    • See reference 6 for more information

  • Options for redundancy and fault tolerance

  • Means to accumulate cumulative frequency scale factor offset relative to grandmaster

    (experimental specification only)

  • New management capabilities and options

  • Higher sampling rates compared to V1; asymmetry corrections

Application Service Interface
  • The timing requirements (jitter wander time synchronization) of the respective applications that use the PTP clock must be met
  • The quality of the clock delivered to the application depends on both the quality of the PTP clock and the application service interface
Basic PTP Concepts
  • PTP Domain:
  • A logical grouping o f PTP clocks that synchronize to each other using the PTP
  • protocol, but that are not necessarily synchronized to PTP clocks in another domain.
PTP clock types

Ordinary clock (OC)

has a single PTP port in a domain and maintains the timescale used in the domain. It may serve as a source of time, i.e., be a master, or may synchronize to another clock, i.e., be a slave. It may provide time to an application or end device.

Boundary clock (BC)

has multiple PTP ports in a domain and maintains the timescale used in the domain. It may serve as a source of time, i.e., be a master, or may synchronize to another clock, i.e., be a slave. It may provide time to an application.

Transparent clock (TC)

A device that measures the time taken for a PTP event message to transit the device and provides this information to clocks receiving this PTP event message.

P2P TC

Peer-to-peer transparent clock (P2P TC): A transparent clock that, in addition to providing PTP event transit time information, also provides corrections for the propagation delay of the link connected to the port receiving the PTP event message. In the presence of peer-to-peer transparent clocks, delay measurements between slave clocks and the master clock are performed using the peer delay measurement mechanism.

E2E TC

End-to-end transparent clock (E2E TC): A device that only measures the time taken for a PTP event message to transit the device and provides this information to clocks receiving this PTP event message; i.e., it does not provide corrections for the propagation delay of the link connected to the port receiving the PTP event message. It does not use the peer delay measurement mechanism but, instead, supports use of the delay request-response mechanism
PTP event messages
PTP general messages
PTP communication path