The Design And Implementation Of SIP Through NAT Which Integrated STUN And HTTP Proxy Technology

SIP is an important network protocol which is widely used in VOIP systems.When IP addresses become relatively scarce,NAT technology and firewall technology are widely adopted by enterprise networks.However,due to the fact that SIP protocol cannot traverse NAT,VOIP communication is thereby rendered inconvenient by NAT.Based on the need and the actual situation to solve the demand of IP address,this thesis studies the existing technology and proposes a new method by combing the technologies of STUN and HTTP Proxy to achieve NAT traversing.In this thesis,the related technologies of NAT are introduced,STUN technology is used to identify the network type,and the corresponding traversing processes are designed according to different network environment.As for the strict restrictions of NAT,this method uses STUN and the HTTP Proxy technology to achieve the traversing.On the basis of demand,the design of the proposed method is analyzed,and the implementation of it is studied and tested by SIPp software.The results show that the system designed in this paper functions normally and has low packet loss rate.It can traverse the strictly restricted NAT including the hindered UDP without the need to change the NAT equipment.Finally,the paper summarizes the research and lists the potential drawbacks of it.