A Comprehensive and Efficient NAT Traversal Scheme on SIP Signaling

摘要

Due to the characteristics of SIP protocol, various NAT network has become a stumbling block for the extensive application on SIP. However, several existing NAT traversal solutions are not suitable for all the NAT networks, or some solutions significantly affect the instantaneity during the interaction of SIP, which is due to that they either need us to modify the existing equipments in the network, or have limitations on their practical application. Therefore, according to the features of SIP protocol and various traversal protocols, this paper proposes a comprehensive and efficient traversal method. It is based on extension protocol of SIP, STUN protocol, and TURN protocol. In detail, this method applies the extension protocol of SIP to the traversal of SIP signaling. For streaming media in asymmetric NAT network, it uses STUN protocol. What's more, TURN protocol is adopted for the traversal of streaming media in symmetric network. Practice has proved that the SIP soft-phone integrated with this method traverses all kinds of network.