Why We Care: PTP Clocks Hierarchy

PTP (Precision Time Protocol) is a protocol used for synchronizing clocks in a network. It is a time synchronization protocol that is designed to provide high-precision time and frequency synchronization for networked devices.

PTP (Precision Time Protocol) is an IEEE 1588 standard protocol that synchronizes real-time clocks of connected nodes in a distributed system using a network. This protocol establishes a leader-follower hierarchy among the nodes (referred to as clocks) where followers synchronize with their leaders, and the leader-follower relationship is determined by a Best Master Clock (BMC) algorithm. Through dynamic relationship determination, the PTP network can simplify the interconnect graph, resolving cycles down to a tree of leaders and followers. The grandmaster, located at the root of the tree, synchronizes with GPS and serves as the ultimate leader for all clocks. Interior nodes in this network are called boundary clocks (BC) and have follower ports and one or more leader ports. PTP can achieve high accuracy, even within sub-microsecond limits on local networks.

PTP works by sending time signals between devices, a best grandmaster, leader, and a follower clocks. The best grandmaster clock sends synchronization messages to leader clocks, and the leader clocks adjust their clock frequency and time to match the best grandmaster clock. The leader clocks send synchronization messages over their network(s), and the follower clocks adjusts their clock frequency and time to match the leader clock. Again, aka boundary clocks. PTP uses precise hardware timestamps to measure the time between devices.

PTP is often used in real-time systems, where accurate timing is essential, such as in audio and video production or industrial automation. It can also be used in some communication networks, such as 5G and industrial Ethernet.

Each of the following company’s products support and /or generate PTP:

1. Leader Electronics Corporation offers the LT8900 and the LT8910A PTP Time Server/Grandmaster Clocks, both of which are designed to provide accurate PTP synchronization for broadcast and post-production applications. The devices generate IEEE 1588-2008 PTP packets with sub-microsecond timing accuracy and support PTP profiles such as the Audio-Video Profile (PTP AV) and the IEEE Power Profile. They also feature two independent 10 Gigabit Ethernet interfaces, allowing for redundant operation and the ability to simultaneously serve as a Network Time Protocol (NTP) server. The LT8910A additionally offers dual electrical inputs, enabling it to function as a redundant PTP Grandmaster clock.

2. Cisco Systems, Inc. offers a range of PTP solutions, including routers, switches, and network interface cards that support IEEE 1588v2. Some of the models that support PTP generation and/or synchronization include the Cisco Catalyst 9300 Series Switches, the Cisco 9200 Series Switches, the Cisco NCS 1002, the Cisco NCS 540 Series Routers, and the Cisco NCS 560 Series Routers. These devices provide high-precision timing capabilities for a range of applications, including 5G mobile networks, industrial automation, and financial trading. They can serve as a PTP Grandmaster clock, Leader clock and/or follower, depending on the application requirements, and have features such as hardware timestamping, clock quality monitoring, and PTP profiles for specific industries.

3. Riedel Communications offers the MediorNet MN-C-OPT-HDMI PTP Media Interface Card, which is designed to provide PTP support and synchronization for its MediorNet media network. The card supports SMPTE ST 2059 PTP profiles and is capable of acting as both a PTP Grandmaster clock and a PTP client. It features multiple input and output ports, including an HDMI port for timecode distribution, and has a high-precision oscillator for sub-microsecond timing synchronization. The card also supports redundancy, multi-casting of PTP messages, and monitoring and configuration via a web-based interface. Additionally, Riedel’s Artist and Bolero communications systems offer PTP synchronization for intercom communication applications.

4. Meinberg Funkuhren offers a variety of PTP Time Servers/Grandmasters that are designed to provide accurate PTP synchronization for a range of applications, including telecom, financial trading, and industrial automation. Some of the models include the LANTIME M900/M600/M4000 PTP Time Servers and the IMS – M400 Industrial PTP Time Server. These Time Servers support IEEE 1588-2008 PTP profiles and various ITU-T G.827x telecom profiles such as G.8275.1 and G.8275.2. They can serve as a PTP Grandmaster clock, Leader, and/or follower clock, depending on the application requirements, and offer features such as hardware timestamping, fault-tolerant design, and redundant power supplies. Meinberg also offers PTP software and network interface cards that support PTP generation and synchronization.

5. Tektronix offers a range of PTP hardware and software products that support PTP generation, including time servers, grandmasters, and clients that generate and measure PTP signals with high accuracy and precision. These devices are specifically designed for PTP and are capable of supporting PTPv1, PTPv2, and PTP-RA.

6. Juniper Networks provides networking equipment that supports PTP generation, including network switches and routers that are capable of handling PTP traffic, as well as software tools for the configuration and management of PTP networks. Juniper’s devices are designed to support PTPv2 and can be used in a variety of PTP network architectures.

7. Ross Video offers PTP generation solutions for the broadcast industry, including PTP time code generators and servers that are designed to synchronize video and audio signals across multiple cameras and equipment. These devices support PTPv2 and PTP-RA and are specifically designed for the broadcast environment.

8. Mellanox Technologies provides network adapters and switches that support PTP generation, allowing for the transmission and synchronization of time-critical data across high-speed networks. Mellanox’s devices support PTPv2 and can be used in a variety of PTP network architectures, including data center and telecommunications applications. Nvidia does not offer a Precision Time Protocol (PTP) implementation as a standalone product. However, Nvidia’s Mellanox networking solutions product line includes NICs (network interface cards) and switches that support PTP as well as other timing protocols such as Network Time Protocol (NTP), Precision Time Protocol (PTP), and IEEE 802.1AS.

These products help enable synchronization throughout data centers and other networked deployments that require tight synchronization between multiple devices, such as high-performance computing, financial trading, media and entertainment industries, and industrial control systems. In addition to PTP support, Nvidia Mellanox’s networking solutions offer low-latency and high-bandwidth capabilities, making them well-suited for demanding applications.

9. Spectracom specializes in precise timing solutions, including PTP servers and PTP-enabled network devices for PTP generation. Spectracom’s devices support PTPv1, PTPv2, and PTP-RA and are designed to provide high levels of accuracy and precision for a variety of industries, including telecommunications, defense, and finance. They also offer software tools for PTP network analysis and management.

10. Selenio Media Communications offers support for various versions of Precision Time Protocol (PTP), including PTPv1, PTPv2, and PTP Profile for Professional Broadcast Applications (PTP-RA). This enables customers to synchronize media processing and transport devices in IP-based broadcasting systems with sub-microsecond accuracy. It offers a single timing source and does not have built-in redundancy.

Note: this is not an exhaustive list of PTP generators or supporters thereof.

In summary, the main differences between PTP offerings are the level of accuracy, redundancy, and interoperability features they offer, allowing customers to select the product that best suits their requirements for timing accuracy, scalability, and reliability.

I’ve been asked if I’m being paid for this post. No, I am not being paid to share this information, nor do I work for any named company within the article.

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