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Spirent TestCenter: IEEE 1588v2 PTP Slave ports stuck in listening state.

Symptoms
  • The Spirent ports don’t reach the right PTP state and stay on listening. On DUT side the PTP counters show no PTP messages received from Spirent.
Environment
  • Spirent TestCenter
    • IEEE-1588v2
    • PTP
Explanation/Resolution
  • It could be Spirent TestCenter was configured with all 1588 PTP devices using the same clock identity.
    • This was confusing the devices since they were receiving clocks from a master that had the same clock identity.
    • To reconfigure, simply highlighted all the devices and do a fill increment on the Clock Identity so that all devices are now different.
    • Then the devices can distinguish between himself and the master clock.
  • It could also be the 1588 PTP devices are configured on a different domain.
    • Set the appropriate domain in DUT or TestCenter so that they are matching.
    • There is a domain column on the TestCenter 1588v2 configuration.
    • You can capture the 1588v2 messages and check the domain number (in wireshark it shows as the subdomainnumber).
  • When set to Slave-Only mode, the priority must be higher than Master.
    • If priority on Slave in Slave-Only mode is lower than the Master it will stay in listening state.
    • Actually it is the expected behavior. The behavior is specified in section ‘9.2 State protocol’ of IEEE1588v2 2008 spec. A slave-only clock can never enter the MASTER state. However if the State Decision or BMCA recommends the state of Slave-Only node to be a Master, it shall remain in Listening state. Meaning the node marked as Slave-only remains in Listening state it’s clock attributes are better than the node connected to it.  Please check the below state diagram for the state transitions in Slave-only mode. 
    • This behavior is in accordance with the below state diagram. 

Root Cause
  • Configuration issue on Spirent side.

Product : Data Center,Spirent TestCenter,IEEE 1588