root@OpenWrt:~# ping 44.1.1.44 -I wan -c 4
PING 44.1.1.44 (44.1.1.44): 56 data bytes
64 bytes from 44.1.1.44: seq=0 ttl=54 time=80.774 ms
64 bytes from 44.1.1.44: seq=1 ttl=54 time=80.527 ms
64 bytes from 44.1.1.44: seq=2 ttl=54 time=80.781 ms
64 bytes from 44.1.1.44: seq=3 ttl=54 time=80.752 ms
--- 44.1.1.44 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 80.527/80.708/80.781 ms
root@OpenWrt:~# ping 44.1.1.44 -I tunl0 -c 4
PING 44.1.1.44 (44.1.1.44): 56 data bytes
64 bytes from 44.1.1.44: seq=0 ttl=50 time=200.975 ms
64 bytes from 44.1.1.44: seq=1 ttl=50 time=200.664 ms
64 bytes from 44.1.1.44: seq=2 ttl=50 time=200.784 ms
64 bytes from 44.1.1.44: seq=3 ttl=50 time=200.830 ms
--- 44.1.1.44 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 200.664/200.813/200.975 ms