Ieee 1588V2 Precision Timing Protocol (Ptp) - Juniper ACX1000 Configuration Manual

IEEE 1588v2 Precision Timing Protocol (PTP)

Copyright © 2017, Juniper Networks, Inc.
Configuring Precision Time Protocol Clocking on page 243
Supported IPv4, TCP, and UDP Standards
The IEEE 1588v2 standard defines the Precision Time Protocol (PTP), which is used to
synchronize clocks throughout a packet-switched network. This synchronization is
achieved through packets that are transmitted and received in a session between a
master clock and a slave clock or remote clock client. The clocks used for the distribution
of accurate time are in an hierarchical master/slave architecture, which includes boundary
clocks, ordinary clocks, and grandmaster clocks. A boundary clock is both a clock source
and a clock client. An ordinary clock is either a clock source or a clock client. However, a
grandmaster clock is always a clock source. An ordinary clock on a device is always a
clock client. In addition, User UDP over IPv4 and unicast mode are used to transport PTP
messages.
NOTE: In ACX Series routers, the grandmaster functionality is supported only
on ACX500 router.
The following key PTP features are supported:
Boundary clock—A boundary clock has multiple network connections and can act as
a source (master) and a destination (slave or clock client) for synchronization messages.
It synchronizes itself to a best master clock through a slave port and supports
synchronization of clients to it on master ports. Boundary clocks can improve the
accuracy of clock synchronization by reducing the number of 1588v2-unaware hops
between the master and the client. Boundary clocks can also be deployed to deliver
better scale because they reduce the number of sessions and the number of packets
per second on the master.
Ordinary clock—The PTP ordinary clock has a single network connection and can act
as a source (master) or destination (slave or clock client) for synchronization messages.
On devices, the ordinary clock is a slave, which receives synchronization reference
messages from a master, either a grandmaster or a master boundary clock. You cannot
configure an ordinary master on a device. However, a boundary clock can provide time
to the ordinary slave.
PTP grandmaster clock—The PTP grandmaster clock communicates time information
to destination or slave ports. The grandmaster clock is an external device to which the
boundary or ordinary clock synchronizes. You cannot configure a grandmaster clock
on a device. However, a boundary clock slave or an ordinary clock slave can receive
time from a grandmaster clock.
Clock source—A clock source is the PTP master clock to which the slave synchronizes.
The clock source is included in the configuration of the slave clock.
Chapter 9: Configuring Timing and Synchronization
237