Thanks for posting to the Support Community! You are correct that the unit will not perform NAT on self sourced traffic. The NAT rules in the firewall are applied inbound on an interface. Since this traffic never comes in on an interface to which a "NAT source" rule is applied, we are responsible for making sure the source IP address is something reachable by the far end when we issue the command. If your goal is just to verify NAT operation within the unit, the "show ip policy-sessions" command is useful. As long as anything on the LAN is generating traffic you can view the NAT take place.
NetVanta 6355#show ip policy-sessions
Policy class "Private":
tcp (600) -> Public
192.168.101.34 62472 188.8.131.52 80 s x.x.x.x 62472
In this example, we see the source IP and port, followed by the destination IP and port. The 's' means that the source was modified to x.x.x.x and the source port was not modified.
Hope this helps!
Thanks so much for the reply!
I was 99% sure that was the case, but was unable to find this documented by Adtran (I'm sure it's out there somewhere).