I have a WS 2008R2 RRAS server running both NAT and RIP. Sometimes, a RIP peer will not receive any response at all.
Capturing the packets showed that the RRAS server sent the packet using (incorrectly) the IP of the public interface of NAT but through the correct private interface. These are two separated interfaces, so I do not understand how this is possible.
Also, this only seems to happen if a neighbor list is used instead of broadcast/multi-cat. If I enabled broadcasting with the neighbor list, then the correct source IP with be chosen for both kinds of packets.