Posted on November 28, 2018 2:32 am
 |  Asked by Gustavo Carneiro
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Hello all! I’m trying to setup a network with PTP distribuition, I’m currently with a PTP Grandmaster connected to an 7150S-64 in boundary mode, everything is ok with this guy and the devices connected to it can sync properly with my PTP, but I also want to send the PTP messages from my Grandmaster to another 7150S connected to the first using a Trunk interface, I’ve already set up this second unit to boundary mode too, and enabled the ptp on the interface connected to the first unit, but it keeps the interface on Master status. What should I do to make it work?

Posted by Kamlesh Sharma
Answered on November 28, 2018 6:28 am

Hi Gustavo,

In this case all the devices which are running PTP should be talking to each other via an untagged VLAN. Could you please make native vlan between the two 7150 devices same as access vlan assigned on interface connected to your grandmaster.


Posted by Alexis Dacquay
Answered on November 28, 2018 6:38 am

This is normal; in a PTP transparent mode a switch would NOT participate in the PTP exchange.
By setting the PTP mode to “boundary”, you make the switch participate:
1) Ports towards the GM. Such port would be a slave clock port (the GM being the PTP master)
2) Ports towards ordinary clocks. Such port would be a master clock port for the slave ordinary clocks (or your 2nd switch trunk interface)

Here is a white paper describing this in more details:


Posted by Gerard Phillips
Answered on November 28, 2018 11:21 am


Boundary Clock will work fine in the scenario you describe.

If the following tips don’t help, perhaps paste the running-config sections for global ptp for both switches, as well as the config for the trunk interface between the switches?

The things to check would include …

— What are the Priority1 settings you are running on the GM, and the 2 switches?
Typically, you’d set the switches to be the same priority, but a bigger number than the GM. This ensures that the GM continues to be the GM.

— Are the announce interval settings consistent between GM and switch, and switch to switch?
per interface, you can set with…
7150-1(config)#ptp announce interval xyz < << exact number depends how many announce messaged you want per second If these are not consistent between the two ends of the BC link, its possible that the BMCA does not give you the result you wanted! -- Have you set the ptp domain to be consistent between GM and the 2 switches? set globally with... 7150-1(config)#ptp domain xyz You can check whether the ports are receiving ptp messages to help debug with... 7150-1(config)#show ptp int eth 9 counters Interface Ethernet9 Announce messages sent: 58318 Announce messages received: 0 Sync messages sent: 50792 Sync messages received: 0 Follow up messages sent: 50792 Follow up messages received: 0 Delay request messages sent: 0 Delay request messages received: 28786 Delay response messages sent: 28786 Delay response messages received: 0 Peer delay request messages sent: 0 Peer delay request messages received: 0 Peer delay response messages sent: 0 Peer delay response messages received: 0 Peer delay response follow up messages sent: 0 Peer delay response follow up messages received: 0 Management messages sent: 0 Management messages received: 0

Posted by Gustavo Carneiro
Answered on December 1, 2018 3:50 am

It worked! Thank you very much for the informations!!

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