IAB Considerations for UNilateral Self-Address Fixing (UNSAF) Across Network Address Translation

As a result of the nature of Network Address Translation (NAT) Middleboxes, communicating endpoints that are separated by one or more NATs do not know how to refer to themselves using addresses that are valid in the addressing realms of their (current and future) peers. Various proposals have been made for "UNilateral Self-Address Fixing (UNSAF)" processes. These are processes whereby some originating endpoint attempts to determine or fix the address (and port) by which it is known to another endpoint - e.g. to be able to use address data in the protocol exchange, or to advertise a public address from which it will receive connections.