Path-Coupled Signaling for NAT/Firewall Traversal

Complex protocols tend to negotiate secondary flows on the application layer. This, in the general case, prevents Firewalls and NATs from allowing or routing them, and communication becomes impossible. This paper describes the requirements and design of an end-application triggered, path-coupled signaling protocol for NAT/Firewall traversal. Finally, the paper shows and discusses a performance evaluation, based on the implementation of the protocol.