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Configuring PTP

Precision Time Protocol (PTP) is a time protocol that can be used to synchronize computers on an Ethernet network. VersaSync supports PTP Version 1 and 2, as specified in the IEEE 1588-2008 standard, via two (2) Ethernet ports.

VersaSync currently can be configured as a PTP Master Clock only.

Next to PTP specifications, this topic describes the PTP menu items and settings, and outlines how to setup VersaSync as a PTP Master.

The PTP Screen

The PTP screen provides PTP status information, and provides access to all configurable PTP settings.

To access the PTP screen, navigate to MANAGEMENT > NETWORK: PTP Setup. The PTP screen will open:

Note: If VersaSync does not detect any PTP traffic, the PTP screen will not display the Statistics information on the right, but a 'No status available' message instead.

The PTP screen comprises five panels, which are described below:

The "Actions" Panel

The Actions panel provides access to the General Settings window (see below), and allows you to Restore the Default PTP Configuration settings.

The General Settings window is organized in five different tabs, which are described below

NOTES:

  • In the descriptions below, defaults settings are set in bold.
  • Settings changed by the user will be maintained when the PTP daemon is stopped and started, and between reboots and powercycles.

The "PTP Services" Panel

The PTP toggle switch is used to stop or start the PTP daemon. When re-starting the PTP daemon, the last user settings will be restored (NOT the Default settings.)

The "PTP Status" Panel

The PTP Status panel provides the following status information:

  • Interface Name: The Ethernet port currently in use (eth 0, or eth1, but not both).
  • Mode: [Currently, the only mode supported is Master Only]
  • Best MasterClock Algorithm: Indicates if the BMC algorithm is turned ON or OFF (see BMC Algorithm tab (Best Master Clock))
  • TwoStep: Indicates the clock mode; PTP has two ways to transmit the initial T1 timestamp of the Sync packet transmission from the Master to the Slave:
    • One-Step Master: The Sync packet is timestamped, then the timestamp is inserted into the Sync packet in real-time, as it is transmitted
    • Two-Step Master: The Sync packet is timestamped, but the timestamp value in the Sync packet is ignored. The actual T1 value is transmitted in a "Follow-Up" packet after the Sync packet.

      Note: One mode or the other must be selected. The default mode is one-step.

  • Unicast: Indicates if Unicast is turned ON or OFF. If OFF, VersaSync will not respond to Unicast Delay Requests. (It will respond to Multicast requests, though.)
  • Negotiation: Indicates if Unicast Negotiation is turned ON or OFF. If OFF, VersaSync will not respond to Negotiation Requests, i.e. there will be no Unicast Sync Messages.
  • Domain: [0 to 255; 128-255 are reserved, as per standards] Indicates the current PTP Domain Number, as defined in IEEE Std 1588-2008 Section 7.1.
  • Transport Protocol: Indicates if IPv4 or Ethernet is currently used.
  • Unicast IP Address: Indicates the interface IP address.

The "PTP Statistics" Panel

VersaSync listens to all PTP traffic on the network. In order to filter statistics to be displayed, the PTP Statistics panel allows you to select a specific PTP node from all the detected nodes on the network, using the Address field.

Note: Note that 0.0.0.0 refers to your local host address, in other words your VersaSync unit.

Select the Message Type for which you would like detailed statistics to be displayed in the panel below.

Note: The choice of Message Types may vary, depending on the selected PTP node.

The Packet Message Statistics Panel

This panel provides statistics for the Message Type and the PTP node selected in the panel above:

All statistics shown are based on the traffic that is detectable by VersaSync, i.e. in a Unicast environment, VersaSync may only detect traffic that is addressed to it, based on switch configuration.

  • Clock Identity: [e.g., "a0:36:9f:ff:fe:37:b9:5d"] What is this hex address?
  • Domain: Domain number of the selected PTP node.
  • Unicast: [0,1] OFF or ON (1)
  • Message Type:
    • Management
    • Sync
    • Follow Up
    • Delay Response
    • Delay Request
    • Announce
  • First Time: [e.g., "2016-08-12 12:23:15"] The first time a packet was received.
  • Last Time: [e.g., "2016-08-12 18:19:15"] The last time a packet was received.
  • Count: [e.g., "1336"] Indicates how many times the selected message has been detected.
  • Average Rate: [e.g., "0.0624986091344933"] Indicates how often the selected message has been detected (in seconds e.g., "1.0" would mean once every second)
  • Missing Packets: [e.g., "1023961"] Indicates how many packets of the selected message type have been missed.
  • Steps Removed: The number of communication paths traversed between the local clock and the grandmaster clock.
    1 = a single path was traversed
    2 = two paths were traversed (there was a boundary clock in the middle).
  • Mean Path Delay: Slave's calculation of path delay between itself and the Master.
  • Offset From Master: Slave's calculation how far off its time is (takes into account Mean Path Delay calculations). When selecting a PTP Slave, and the Management message type, this field will be populated with data provided by the Management interface.

Note: If the IP address 0.0.0.0 is chosen (i.e., the local unit), many of the values above will be "0".

Enabling/Disabling PTP

To enable or disable PTP:

  1. Navigate to MANAGEMENT > NETWORK: PTP Setup.
  2. In the PTP Services panel, slide the toggle switch to ON or OFF.

Selecting PTP Multicast Mode

To enter Multicast mode, perform the following steps:

  1. Navigate to MANAGEMENT > NETWORK: PTP Setup.
  2. In the Actions panel, click General Settings.
  3. Open the Network tab.
  4. Uncheck the Unicast checkbox, and configure the Multicast Ttl field below.

Selecting PTP Unicast Mode

To enter the Unicast mode, perform the following steps:

  1. Navigate to MANAGEMENT > NETWORK: PTP Setup.
  2. In the Actions panel, click General Settings.
  3. Open the Network tab.
  4. Check the Unicast checkbox, and configure the settings below (see The "Actions" Panel).

Configuration — General Steps

  • Ensure that the Ethernet port used for PTP is connected to the network, and its speed is 100 Mb/s: Navigate to MANAGEMENT > NETWORK: Network Setup, and verify the STATUS in the Ports panel.
  • Be sure that valid time and 1PPS references are currently selected: Navigate to MANAGEMENT > OTHER: Reference Priority, and confirm Reference Priority configuration, and Reference Status. Note that in order to operate properly as a Master Clock, VersaSync must be synchronized to a non-PTP reference. The built-in GNSS reference provides all information needed with no user intervention. Should you, however, be using a different reference, ensure that it transmits the following information.
    • The proper TAI or UTC time (including the current year)
    • The current TAI to UTC offset (required even if the reference’s time is in TAI)
    • Pending leap second information at least a day in advance.