Last updated on December 27, 2018
Assume a NAT has Endpoint Independent Mapping behavior for both UDP and TCP. Although I understand that if a machine would send a UDP datagram to one destination and port and then send another UDP datagram to a different destination and port, it would get the same mapping for both (assuming it sent those UDP packets from the same port number), I am unsure of how the NAT would behave if the protocols being used are different for these two different destinations. In other words, if a machine assigned the source port number 7000 to any layer-4 datagram it sends out, and it starts off by sending a UDP datagram to some destination Y1:y1 (IP:port) and then sends a TCP segment to some destination Y2:y2, where Y1:y1 != Y2:y2, would the NAT mapped port number for the UDP datagram end up being the same actual number as the NAT mapped number for the TCP segment?
I've read RFC 4787, 5382 and 5128 and I just need a bit of clarification.