Cisco 3548 cant receive ptp multicast 224.0.1.129 sync and follow up

[rehadiri]

Hello,

Cisco 3548 configured for ptp not working properly , 

The configuration is made as it is said in the document https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3548/sw/system_mgmt/602/b_N3548_System_Management_Config_602A11/b_N3548_Sysetm_Management_Config_602A11_chapter_011.html

There is a vlan ( vlan 555 ) for ptp , each vlan port is ptp enabled and ( ptp vlan 555 ) is said for each interface. The L3 IP interface is communicating with GM clock  and we can see that the source ptp ip address -> 224.0.1.129 sync and follow up messages coming continuously  .  But the L3 interface stays Master . cant switch to Slave.

On the other hand when  i start a local clock on a vlan port that port can switch to PTP Slave.

Do we need to make IP igmp join stuff for 224.0.1.129 multicasts ? Is Feature PTP cant handle that ?

Thanks   

[rehadiri]

I forgot to mention Cisco 3548 software. The NXOS version is  9.2.(2)

Thanks

[rehadiri]

I have to share some striking information this issue;

There is a big misperception about the source of the PTP server . As i saw the source IP address of the PTP server in the dumpcap log, i thought that the announce / sync and follow up messages are coming from the real PTP server . But unfortunately this is not the case. Actually there isn't any PTP message coming from that server. This is uncovered by checking the input interface counters. What is Cisco doing is its becomes the Master and starts generating GM clock by insterting the IP address of the PTP server in the source IP address field . So thats why i saw all the PTP interfaces as Master .

I should check why there is no PTP message coming from that server.

Thanks.   

[hzg]

you can config this command: no ptp grandmaster-capable
By default Nexus 3k is “ptp grandmaster-capable”, so disable this capability to get synched with the GM.