Recent research TSN.

TSN The most basic concept and requirement in the network is clock synchronization , Because in a network , Only when the clock is synchronized can real-time evaluation and processing be carried out , If the clocks are not synchronized , There is simply no agreement on time ,TSN It can't be achieved .

Test network topology ：

SIG-0101 Is a TSN Switch ,swp0 - swp3 yes TSN so . 

eno0 And swp2 There is no need to connect . This connection is only for the gateway as a endpoint nothing more .

This network card supports PTP agreement , have access to ptp4l Hardware mode of , The accuracy of clock synchronization may be affected by the real-time performance of the operating system .

This network card can only be used ptp4l The software model of , When running, you need to add   -S , Otherwise, it will be reported that the Internet port does not support .

I won't support it ptp Hardware clock .

  Run the command on the gateway ：

-l7 You can output more logs

./ptp4l -i swp2 -p /dev/ptp1 -f gPTP.cfg -2 -m

gPTP.cfg The content of the document

[global]
gmCapable               1
priority1               128
priority2               248
logAnnounceInterval     0
logSyncInterval         -3
syncReceiptTimeout      3
#neighborPropDelayThresh        800
neighborPropDelayThresh 80000
min_neighbor_prop_delay -20000000
assume_two_step         1
path_trace_enabled      1
follow_up_info          1
transportSpecific       0x1
ptp_dst_mac             01:80:C2:00:00:0E
network_transport       L2
delay_mechanism         P2P

Run at test end

 ./ptp4l -i eth0  -f gPTP.cfg -2 -m

You can see , At the beginning, there was a big clock gap , But soon the clock gap fell . As low as 5,9,6,7ns.