IEEE 1588 PTP
Solutions with IEEE 1588 PTP Synchronisation Protocol
We enable the support of IEEE 1588 PTP in software and hardware for cloud networks, data centre infrastructures, switches and routers to ensure perfect synchronisation.
A packet-based two-way communication known as the IEEE 1588 Precision Time Protocol (PTP) synchronises distributed clocks to sub-microseconds via Ethernet or IP-based networks.
Benefits of IEEE 1588
IEEE 1588 can provide real-time applications with
- precise time-of-day (ToD) information,
- time-stamped inputs,
- scheduled and synchronised outputs for various systems.
IEEE 1588 is today's only standardised terrestrial mechanism to deliver phase/time via a packet-based network with nanosecond accuracy. Its application area ranges from mobile networks, industrial process control, audio-visual networks, smart energy distribution to transportation, automotive, and IIoT.
How Does It Work?
IEEE 1588 works by exchanging two-way timing messages from the master clock to the slave clock. In the message, the slave clock receives information about the time the master clock is on. It is easy to determine the delay. The protocol then estimates the delay of the one-way message, halving the round-trip delay.
PTP clock synchronisation profiles were introduced in IEEE 1588-2008 to allow other standards bodies (ITU-T, IETF, SMPTE, AES, IEC, Avnu, AUTOSAR, LXI, AIA) to adopt PTP protocol to particular applications: financial/enterprise, professional broadcast, power industry, test and measurement.
Promwad enables support of the following profiles:
IEEE Std 1588-2019 for generic applications;
G8275.1, G.8265.1 for telecommunications;
IEEE Std 802.1AS for audio/video, industrial automation, and automotive applications.
How Promwad adopts this technology
To deliver the functionality of IEEE 1588v2 Precision Time Protocol, Promwad uses Microchip SparX-5i Ethernet switches augmented with Microchip 1588v2 PHYs, and 10G PHYs.
Here is the model range we use:
- Ethernet switches: VSC7546TSN, VSC7549TSN, VSC7552TSN, VSC7556TSN, VSC7558TSN.
- PHYs / 10G PHYs: VSC8572, VSC8574.
IEEE 1588v2 PTP is implemented as an application-level module in the IStaX Software Development Kits (SDKs) running on Microchip Ethernet switches hardware assisted by rewriter, egress port modules, and timing-aware PHYs.
The following features are implemented as part of PTP:
Ordinary clocks and boundary clocks using basic delay and peer-to-peer mechanisms
Peer-to-peer / end-to-end transparent clock
Local clock and servo
Best master clock algorithm
The protocol supported by default is Ethernet PTP over Ethernet multicast. It is possible to configure PTP over Ipv4 multicast or unicast.
Boundary clocks support both multicast and unicast configuration. The slave-only clock can be configured for up to five master IP addresses. When operating in IPv4 unicast mode, the slave is configured for up to five master IP addresses. The slave then requests announce messages from all the configured masters. The slave uses the BMC algorithm to select one as the master clock and then requests sync messages from the selected master.
Design can be equipped with OCXO providing IEEE 1588 slave functions and timing holdover capability. Timing failover operation can be revertive or non-revertive.
Our Case Studies in Telecom
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How to implement Precision Time Protocol?
PTP is implemented in hardware, software or both. The protocol is implemented in PTP-enabled systems and network equipment.
What is the Precision Time Protocol? What is the PTP protocol?
PTP stands for "Precision Timing Protocol" and is described in IEEE Standard 1588.
How does IEEE 1588 work?
The Precision Time Protocol determines the server and client operating modes and the master and slave clock synchronisation messages. The slave synchronises with the master, which is the source of time. A master that is synchronised to a time reference, such as GPS or CDMA, is referred to as a grandmaster.
The protocol includes a master sync message, a master delay response message, and a slave clock delay request message. The Best Master Clock (BMC) technique enables several masters to agree upon the best clock for the network in addition to the messages.
At least one master and one slave are needed for clock synchronisation via LAN. A single master can synchronise with several slaves. The slaves use synchronization messages from the master clock to adjust their local clocks. The master and slave clocks both record exact timestamps.