Topology file

Enhanced PTP User Guide (UG1602)

Document ID
UG1602
Release Date
2022-10-18
Revision
1.0 English

When viewed on a sfptpd slave server, the topology file presents a PTP clock hierarchy diagram showing all clocks local to the slave server and PTP network elements between the slave and master clock.

  • A PTP Boundary Clock would be visible in the file as a parent to the slave.
  • A PTP Transparent Clock will also be visible in the topology file.

The topology file identifies the current state of the selected slave clock, the interface being used to receive PTP messages and the timestamping mode being used. Each clock in the topology is identified by its UUID which is derived from its MAC address. Nanosecond values between clocks are the offset values recorded during the last file update.

The following output is a example of a topology file currently showing alarm states.

state: ptp-slave-alarm
alarms: no-sync-pkts no-delay-resps
interface: eth2 (eth2)
timestamping: hw
====================

            grandmaster
       000f:53ff:fe16:0474/1
                 |
                 |
           -170.000 ns
                 |
                 |
                 v
          phc0(eth2/eth3)
        000f:53ff:fe21:9bb0
                 |
                 |
            -52.688 ns
                 |
                 |
                 v
              system
              system

In the above example, the slave is in an alarm state indicating that Sync messages and Delay_Response messages are not currently being received from the master clock.

The topology file can be periodically monitored, for example, using a script to extract key fields, to monitor the current connection state and synchronization status of the PTP slave.

Note: During normal operation the topology file is updated every second. However, alarm or state changes are reflected in the file immediately.