To Next Page

To Previous Page

GEN7iB

282

GEN series SYNCHRONIZATION METHODS

14.2 PTP

14.2.1 PTP

(1)

technology background

(1)

Source: Wikipedia

the free encyclopedia

The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout

a computer network. On a local area network, it achieves clock accuracy in the sub-mi-

crosecond range, making it suitable for measurement and control systems.

PTPwasoriginallydenedintheIEEE 1588-2002standard,ociallyentitled“Standard

for a Precision Clock Synchronization Protocol for Networked Measurement and Control

Systems” and published in 2002. In 2008, a revised standard, IEEE 1588-2008 was

released. This new version, also known as PTP Version 2, improves accuracy, precision

and robustness but is not backwards compatible with the original 2002 version.

Architecture

The IEEE 1588 standards describe a hierarchical master-slave architecture for clock

distribution. Under this architecture, a time distribution system consists of one or

more types of communication media (network segments) and one or more clocks. An

ordinary clock is a device with a single network connection and is either the source

(master) of or destination (slave) for a synchronization reference. A boundary clock

has multiple network connections and can accurately bridge synchronization from

one network segment to another. A synchronization master is selected for each of the

network segments in the system. The root timing reference is called the grandmaster.

The grandmaster transmits synchronization information to the clocks residing on its

network segment.

The boundary clocks with a presence on that segment then relay accurate time to the

other segments to which they are also connected.

AsimpliedPTPsystemfrequentlyconsistsofordinaryclocksconnectedtoasingle

network. No boundary clocks are used. A grandmaster is elected and all other clocks

synchronize directly to it. IEEE 1588-2008 introduces a clock associated with net-

workequipmentusedtoconveyPTPmessages.ThetransparentclockmodiesPTP

messages as they pass through the device. Timestamps in the messages are corrected

for time spent traversing the network equipment. This scheme improves distribution

accuracy by compensating for delivery variability across the network.

HBK GEN7iB GEN Series User Manual

Questions and Answers: