Method for sustaining NAT address in SIP network system and device thereof

Abstract

The invention provides a Network Address Translation (NAT) address binding and maintaining method and a corresponding device and system in a Session Initiation Protocol (SIP) network system. In the SIP network system, an SIP user agent is connected with a second network SIP server through an NAT / PAT device of a private network. The method comprises the following steps: a) the SIP server periodically creates a NOTIFY message to the SIP user agent; b) the SIP user agent responds to the NOTIFY message so as to maintain the binding of the NAT / PAT device to the NAT address. According to the method and the device provided by the invention, the connectable performance of the SIP user agent in the private network can be effectively maintained, and the reliability of the SIP network system is improved.

Description

technical field [0001] The present invention relates to a multimedia communication network system and its device based on the Initial Session Protocol (SIP) protocol. Background technique [0002] As a typical broadband application, multimedia communication protocols represented by Voice over IP (VoIP) are facing unprecedented development opportunities. In terms of VoIP technology and standards, the main protocols used are H.323, MGCP and SIP. These three communication protocols can all complete the voice processing on the IP network. The H.323 protocol is widely used, and the SIP protocol has gradually become the mainstream protocol of VoIP due to its characteristics of being more open, easier to expand, and closely integrated with the Internet. [0003] However, in the current network environment, the IPv4 address space is severely exhausted. To solve this problem, people have designed a network address translation (NAT) / port address resolution (PAT) device. The network ...

AI Technical Summary

Problems solved by technology

[0006] Mode 1: The SIP terminal located behind the NAT / PAT device in the private network periodically sends a registration (REGISTER) request to the SIP server located in the public network. The request period must be lower than the address binding period of the NAT / PAT device, but this mode It has the following disadvantages: 1), compared with other NON-INVITE request methods, the REGISTER request needs to consume more SIP server resources; 2), the SIP server cannot pass some useful information to the SIP terminal through the corresponding REGISTER response message; 3 ), all SIP terminals have to support this periodic "Pinging" method

[0007] Method 2: The SIP server located in the public network periodically sends optional OPTIONS (a request method defined by the SIP protocol, used to query the performance of the receiver) request to all SIP terminals located behind the NAT / PAT device in the private network , the request cycle must be lower than the NAT / PAT device address binding cycle, but this method has the following disadvantages: 1) Compared with other methods, responding to the OPTIONS request needs to consume more SIP terminal resources, and the response message needs to contain additional Header information, such as Allow, Accept language, etc., have a great impact on the performance of SIP terminals; 2), poor reliability, when the SIP server is in an overloaded working state and cannot generate OPTIONS requests to notify SIP terminals in time, the address binding will expire ; 3), the scalability is poor, because the OPTIONS request is only a simple request message, it is impossible to carry additional information to the SIP terminal

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