Network Address Translation (NAT) causes well-known difficulties for peer-to-peer (P2P) communication, since the peers involved may not be reachable at any globally valid IP address.
M. Wander, S. Holzapfel, A. Wacker, and T. Weis. 9th IEEE Consumer Communications and Networking Conference, CCNC 2012, Las Vegas, Nevada, USA, (14 - 17 January 2012)