PTP Instance Troubleshooting

The most common error encountered using multi-instance PTP is a failure to start one or more instances after running the ptp-instance-apply command. This is often due to an invalid configuration or missing parameter.

This section provides some troubleshooting steps to assist with determining the error.


After running the ptp-instance-apply command, the 250.001 alarm will appear if the PTP instances could not be created/started properly. The system may also show the 200.011 alarm if, after an unlock, PTP instances were unable to start.

The following example shows these alarms as they would appear in tabular terminal output.

| 250.001  | controller-0 Configuration is out-of-date.          | host=controller-0     | major    | 2022-02-25T21: |
|          |                                                     |                       |
| 200.011  | controller-0 experienced a configuration failure.   | host=controller-0     | critical | 2022-02-25T20: |
|          |                                                     |                       |          | 47:59.561262   |
  1. Determine if there was a PTP-instance failure by looking at the latest runtime puppet logs.

    sudo less /var/log/puppet/latest/puppet.log
    # Searching for "Error" in the log file shows this entry
    2022-02-28T17:26:49.529 ESC[1;31mError: 2022-02-28 17:26:49 +0000 Systemd start for ptp4l@ptp4l-legacy failed!
  2. Once the instance has been identified, examine the config file for configuration errors.

    ~(keystone_admin)]$ cat /etc/linuxptp/ptpinstance/ptp4l-ptp4l-legacy.conf
    ## Default Data Set
    boundary_clock_jbod 1
    clock_servo linreg
    delay_mechanism E2E
    domainNumber 0
    message_tag ptp4l-legacy
    network_transport L2
    summary_interval 6
    time_stamping hardware
    tx_timestamp_timeout 20
    uds_address /var/run/ptp4l-ptp4l-legacy
  3. Start the service manually and check for errors.

    ~(keystone_admin)]$ ptp4l -f /etc/linuxptp/ptpinstance/ptp4l-ptp4l-legacy.conf

    In this example the ptp4l program indicates that there is no interface specified, which is confirmed by the contents of the config file above.

  4. Check using the relevant system commands to see if there is an interface assigned to this instance and add one as required.

Additional tools


PTP management client.

Used to interact with ptp4l and read/set various PTP parameters.

$ man pmc

# General command format:
sudo pmc -u -b 0 -f <path to ptp4l.conf for targeted instance> -s <path to uds socket for target instance> 'COMMAND GOES HERE'

For Example:

pmc -u -b 0 -f /etc/linuxptp/ptpinstance/ptp4l-ptp1.conf -s /var/run/ptp4l-ptp1 ‘get PORT_DATA_SET’

Directly control PHC device clock.

Used to perform operations on the physical hardware clock (phc). PHC_CTL can be used to set the time on a NIC, check the delta between the NIC and the system clock, adjust the clock frequency.

$ man phc_ctl

# Example commands

phc_ctl <ptp_interface> get
phc_ctl <ptp_interface> cmp

# Rhis syncs the NIC clock to the system clock
phc_ctl <ptp_interface> set

Check if PTP traffic is sending or receiving on a given interface.

You can capture L2 ptp traffic by filtering on proto 0x88F7

sudo tcpdump ether proto 0x88F7 -i <ptp_interface>

# Write it to file

sudo tcpdump ether proto 0x88F7 -i <ptp_interface> -w <output_file.pcap>