vladimiroltean
commented
4 years ago the "basetime" in NXP board should be an integer multiple of the "basetime" in Cisco IE4000
If the Cisco IE4000 supports IEEE 802.1Qbv (which it looks like it does), then yes.
how to get the basetime parameter from the message of time-synchronization?
Is this a question on how to use the Cisco equipment?
The base-time argument is not fixed. All nodes in the network need to agree, using an application-defined protocol, upon a time in the nearby PTP future that would work as common base-time for all of them. A trivial protocol might be:
- The master checks the synchronization offset of all its slaves (or each slave sends a message to the master when it's synchronized). The threshold can be e.g. +/- 50 ns. With linuxptp, the synchronization offset can be derived either from the system logs, or with pmc from the TIME_STATUS_NP dataset (you need to specify "-t 1" for 802.1AS).
- By convention, the master and all slaves install port schedules starting with a base-time equal to the beginning of the next second (floor(current-time) + 1).
Such a protocol, but for plain 1588 instead of 802.1AS, is exemplified in the time-test.sh program from tsn-scripts.
Hope this helps, -Vladimir
My questions: How to use the "time-synchronization for Qbv"? (Or, how to connect time-synchronization and Qbv gate function?)
I have ls1028ardb with openil 1.6 and it can sync with Cisco IE4000 successfully by using ptp4l with profile gPtP.
As we know, the time-synchronization is fundamental for Qbv-gate function. Even the board can be synced well, how can I use the synced "time" from Cisco IE4000?
I noticed that we can set up "basetime" by using tsntool for the Qbv gate function. In my understanding, the parameter "basetime" should be connected to time-synchronization. In other words, the "basetime" is the middle bridge between time-synchronization and Qbv-gate function. Because I think the parameter "basetime" is the start-point time for executing Qbv-gate function, so the "basetime" in NXP board should be an integer multiple of the "basetime" in Cisco IE4000. But how to get the basetime parameter from the message of time-synchronization. Or, in the case of my understanding of "basetime" is wrong, how can I use the "time-synchronization" for Qbv-gate function?