 This makes port prediction straightforward, as it is the same source port for each packet.Furthermore, "port preservation" in NAT for TCP allows P2P protocols to offer less complexity and less latency because there is no need to use a third party (like STUN) to discover the NAT port since the application itself already knows the NAT port.However, if two internal hosts attempt to communicate with the same external host using the same port number, the external port number used by the second host is chosen at random.