gPTP port roles

[John_Lemonovich]

I am using an X430-8p switch to connect two Altera Arria 10 kits running Linux PTP. I am using L2 802.1AS (gPTP) and I'm wondering how the port role assignment should work in my case. If I would like my one A10 kits to be GM, and the other one to be an OC slave, what should be the port roles? I am able to manipulate priorities to get both A10 nodes as slaves to the switch, and in this case, the sync works very well (~20ns or less) but when I have one as master and one as slave, they seem to sync but very poorly with large path delays.

In this case, where I would like one A10 kit to be master and one as slave (through the switch), should both switch ports report as Passive gPTP port role? Is there a way to force ports to passive role?

Thank you,
John

[Chad_Smith1]

Difficult to say what may have happened, obviously something abnormal. We probably need to take a look at this via a GTAC case.

[John_Lemonovich]

Yes with the two devices connected together (that was the starting point) - they work perfect...one as GMC one as slave. I since have BMCA ON which explains some of the messages/timeouts I was seeing. Yesterday I tried a test turning on one port at a time - I started with port 3 on with one of my devices as GMC. The switch seemed to work fine as slave to my GMC. I then turned on port 5 and booted my other device and my device reported as slave to the switch port 5 as master. Then out of nowhere my two boards sync'd (one as master one as slave) as I have been trying, and the sync and path delays were excellent. That worked for about 10 minutes and then something happened where the switch console was running painfully slow and I had to reboot. That's where I left off...

[Chad_Smith1]

With BMCA off I don't think we will send Sync or Announce messages. It really sounds as if the device isn't actually trying to act as GMC. That could explain the behavior with the other slave as well.

Is it possible to directly connect the two devices (omitting the switch)? If so, does everything work as expected?

[John_Lemonovich]

It's not sending timeout messages over Ethernet, it's printing to the console that it's not receiving sync/announce messages, presumably as information during the BMCA. It may be just because my debug log level is so high that it's printing anything and everything. I can open a support case, I didn't know if maybe any users on here would have run into this scenario using Altera devices with LinuxPTP.
I am also now setting up a new GMC on a Linux PC so that I can just make my two A10 devices slaves, to see if that works well. When I let the switch be master, both of my A10 devices sync as slaves and the performance is great ... sync'd to ~20ns or so on the PPS output.