Help needed in understanding PTP configuration for CISCO IE 4000 Industrial switch

[pm17]

Hello we are trying to use the CISCO , IE 4000 to switch communication between master nodes and slave nodes . For testing PTP we are using link ptp version 1.8

We have some issues in making the time sync work  and to see the functionality of the 802.1 ptp profile.

We have done the following tests

1.  Master node to the Slave node without the CISCO switch ( It seems to work OK with a offset of +/- 20 ns)
2. CISCO switch as master to two slaves , synchronization works but we with a big offset of +/- 500 ns
3. We use another node as master, communicating to two slave nodes via the CISCO switch. We seem to loose the synchronization between the switch and slave node but the synchronization between master node and CISCO works. Also , the MASTER capable ports on the CISCO switch don’t seem to have 802.1AS capability.

What could be the reason for lack of synchronization? And why do the ports loose the PTP configuration – Is it possible to configure the switch in another configuration to reduce the synchronization error ?