I found that when I input ifconfig gr0 192.168.200.1 on machine A, and input ifconfig gr0 192.168.200.2 on machine B at the same time, both machines showed Tx and Rx packages.
But when I ping 192.168.200.2 from machine A ( or ping 192.168.200.1 from machine B respectively), one window of machine A only showed Tx packages and another window showed "Destination Host Unreachable". Machine B showed both Rx/Tx packages.
It means that machine B can successfully received packages from machine A but A failed to receive replied packages from machine B. It confused me that the packages tx/rx were succeed before the ping. Anyone has idea?
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Regards,
Weixian Zhou