Synchronize PTP Time (IEEE 802.1AS)#

What is PTP?#

Precision Time Protocol (PTP) provides sub-microsecond time synchronization across Ethernet devices, enabling accurate latency measurements.

Install PTP Tools#

sudo apt-get update
sudo apt-get install -y linuxptp git
git clone https://git.code.sf.net/p/linuxptp/code linuxptp
cd linuxptp

PTP Commands#

The TSN switch is configured to act as the PTP Grandmaster clock. On each Arrow Lake machine, execute the following command to synchronize the system clock using PTP.

Note: Make sure to replace enp1s0 with the actual network interface name associated with the i226 network card.

  1. Start the PTP daemon (ptp4l).

    Start the ptp4l daemon on each machine, specifying the network interface (enp1s0) related to the i226 network on that machine and the gPTP configuration file.

    sudo ptp4l -i enp1s0 -f configs/gPTP.cfg --step_threshold=1 -m -s

  2. Synchronize the System Clock (phc2sys).

    Synchronize the system clock with the PTP hardware clock (PHC).

    sudo phc2sys -s enp1s0 -c CLOCK_REALTIME --step_threshold=1 --transportSpecific=1 -w -m

  3. Verify Synchronization.

    Check the phc2sys output to ensure the offset is within acceptable limits (e.g., less than 50ns). The output should look similar to this:

    phc2sys[1234.567]: CLOCK_REALTIME phc offset 12345 s0 freq +0 delay 1234