Wu MW., Huang Y., Chen IY., Lu SK., Kuo SY. (2006) A Scalable Port Forwarding for P2P-Based Wi-Fi Applications. In: Cheng X., Li W., Znati T. (eds) Wireless Algorithms, Systems, and Applications. WASA 2006. Lecture Notes in Computer Science, vol 4138. Springer, Berlin, Heidelberg
A few killer applications that rocked the Internet community these years are peer-to-peer (P2P) file-sharing applications and VoIP (voice over Internet Protocol) telephony services. Unlike traditional client-and-server applications in which servers are services provider and by default should be public addressable, each peer in P2P networks can play both roles (client and server). However, legacy usage of the network address translation (NAT) module on most wireless access points (APs) causes new problems with emerging P2P communications especially in opposing APs (both peers of an Internet connection are behind AP) where each peer uses private Internet Protocol (IP) address and neither side has global visibility to each other. This article therefore examines such issue from three approaches, 1) leveraging the complexity of client application, 2) introducing additional intermediate gateways and protocols and 3) enhancing the wireless AP itself. Client-based solutions such as UDP/TCP hole-punching suffer from race condition while gateway-based solutions tend to incur overhead for interoperability and deployment. This paper proposes a scalable port forwarding (SPF) design for wireless AP, which introduces little or negligible time and space complexity, to significantly improve the connectivity and scalability of a conventional AP by 1) lessening the race condition of P2P traversals in opposing APs, 2) multiplexing the port numbers to exceed theoretical upper bound 65,535 and 3) allowing more servers to bind to a specific port.
Wi-Fi Access Point (AP) Peer-to-Peer (P2P) Port Forwarding Network Address Translation (NAT)