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# - Add complete linuxptp-daemon pods to example output # - Update NodePtpDevice to show 5 workers with E810 NICs # - Fix MCP output with correct columns # - Change interface names to ens7f0 (E810 standard) # - Add note about customizing interface names # Resolves: TELCODOCS-2500
36 lines
3.1 KiB
Plaintext
36 lines
3.1 KiB
Plaintext
// Module included in the following assemblies:
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//
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// * networking/ptp/about-ptp.adoc
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:_mod-docs-content-type: CONCEPT
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[id="ptp-elements_{context}"]
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= Elements of a PTP domain
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[role="_abstract"]
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PTP uses a leader-follower hierarchy of grandmaster, boundary, and ordinary clocks to synchronize time with high precision across network nodes.
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The clocks synchronized by PTP are organized in a leader-follower hierarchy.
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The hierarchy is created and updated automatically by the best master clock (BMC) algorithm, which runs on every clock.
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Follower clocks are synchronized to leader clocks, and follower clocks can themselves be the source for other downstream clocks.
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.PTP nodes in the network
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image::319_OpenShift_PTP_bare-metal_OCP_nodes_1123_PTP_network.png[Diagram showing a PTP grandmaster clock, boundary clock, and ordinary clock syncing from a GPS satellite that is connected to the PTP grandmaster clock. The boundary and ordinary clocks are synced to the grandmaster clock.]
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The three primary types of PTP clocks are described in the following sections.
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Grandmaster clock:: The grandmaster clock provides standard time information to other clocks across the network and ensures accurate and stable synchronization. It writes time stamps and responds to time requests from other clocks. Grandmaster clocks synchronize to a global navigation satellite system (GNSS) time source. The grandmaster clock is the authoritative source of time in the network and is responsible for providing time synchronization to all other devices.
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Boundary clock:: The boundary clock has ports in two or more communication paths and can be a source and a destination to other destination clocks at the same time. The boundary clock works as a destination clock upstream. The destination clock receives the timing message, adjusts for delay, and then creates a new source time signal to pass down the network. The boundary clock produces a new timing packet that is still correctly synced with the source clock and can reduce the number of connected devices reporting directly to the source clock.
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Ordinary clock:: The ordinary clock has a single port connection that can play the role of source or destination clock, depending on its position in the network. The ordinary clock can read and write timestamps.
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[id="ptp-advantages-over-ntp_{context}"]
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== Advantages of PTP over NTP
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One of the main advantages that PTP has over NTP is the hardware support present in various network interface controllers (NIC) and network switches. The specialized hardware allows PTP to account for delays in message transfer and improves the accuracy of time synchronization. To achieve the best possible accuracy, it is recommended that all networking components between PTP clocks are PTP hardware enabled.
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Hardware-based PTP provides optimal accuracy, since the NIC can timestamp the PTP packets at the exact moment they are sent and received. Compare this to software-based PTP, which requires additional processing of the PTP packets by the operating system.
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Before enabling PTP, ensure that NTP is disabled for the required nodes. You can disable the chrony time service (`chronyd`) using a `MachineConfig` custom resource.
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