Just a snippet of a funny observation: I've discovered the config parameter "clock_servo nullf" . Very good - that answes another need I had: to let the PHC freewheel along the ultimate external reference (10MHz -> PLL_synth -> 25 MHz from the PTP GM out of band), and let ptp4l do the talk and calculate the delays and offsets that it can obsereve on the network. It seems to work fine. On a real-wold network I may also need to raise the bar for step-wise adjustment (for this measurement to proceed unhampered).
Just to test if it works, I've tried L2 multicast through an old D-Link DGS-1216T. It does work, the (p)delay is about 2 microseconds. The switch does let both P2P Pdelay and E2E Delay through just fine. And the funny point is: while the E2E transactions result in no asymmetry, the P2P transactions result in about +60 nanoseconds of additional asymmetry. That's curious... That's over two metallic gigabit hops. For comparison, straight against the GM, I have about 7 or 10 ns of (p)delay and about -20 ns of asymmetry, which may well correspond to the length of my PPS cabling (that I use to pre-settle the PHC). Yes I'm having fun with my toys :-D Frank _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
