USRP problem


I have a problem about USRP daughterboard RFX2400.

I use “” to test if some nodes can communicate with each other
in 2.4GHz by pinging function. Say there are three nodes: N1, N2 and N3.
N1 & N2 can ping with each other and N2 & N3 can receive the ping
packets too. However, N1 & N3 cannot receive the ping packet from each
other. The distances between these three nodes are same. So, does anyone
know what’s the reason causes that? Or are there any test scripts can
test if USRP works correctly or not? Is it possible that USRP did
receive the ping packets but cannot forward them through TUN/TAP driver
to User interface?

Thanks for any replies in advance!