hello:  

     I ues vpp18.10.  Using iperf like this:inside network: iperf -c 192.168.11.12  -u -i 1  -b 50M -t 10,outside network: iperf -s -u  -i 1.

     10second later,VPP will abort. 

     VPP config like this:

set interface ip addr GigabitEthernet2/6/0 12.0.3.1/24
set interface ip addr GigabitEthernet2/7/0 192.168.11.1/24
set interface state GigabitEthernet2/6/0 up
set interface state GigabitEthernet2/7/0 up
set interface nat44 in GigabitEthernet2/6/0 out GigabitEthernet2/7/0
nat44 add interface address GigabitEthernet2/7/0