Impact of Network Address Translator Traversal on Delays in Peer-to-Peer Session Initiation Protocol

Peer-to-Peer Session Initiation Protocol (P2PSIP) is a distributed communication system being standardized in the Internet Engineering Task Force (IETF). Since it uses the peer-to-peer paradigm, P2PSIP faces the problems created by Network Address Translators (NATs); even peers located behind NATs need to be able to not only initiate connections to other peers but also accept connections initiated by other peers. In this paper, we study the impact of standardized NAT traversal solutions, namely Session Traversal Utilities for NAT (STUN), Traversal Using Relays around NAT (TURN), and Interactive Connectivity Establishment (ICE), on delays in P2PSIP overlay networks. These delays are studied from the viewpoint of wireless and wired nodes acting as clients in a P2PSIP overlay network running in the PlanetLab. The delays are also compared to those of the traditional client/server Session Initiation Protocol (SIP).