Nat penetration of gb28181

One 、 National standard gb28181 Intranet through

Reference resources ：

RFC3581——SIP Medium rport Mechanism
VIA Header fields
eXosip obtain IP And port

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National standard gb28181 Cross network （ Cross router ） Analysis of the situation of ：

The lower platform is behind the intranet switch , The superior platform is on the public network , Because the camera in the intranet will pass through a gateway when sending information to the public network , The gateway will use nat Protocol conversion intranet port , There is intranet penetration , The port mapped from the intranet to the extranet will change , Therefore, there should be a set of mechanisms for penetration , Because the national standard is based on sip Agreed ,sip Use of Intranet penetration under rport Mechanism , If the request is sent without rport The logo is not to enable this mechanism ,

When the device is registered , We need to record the equipment IP And port , In order to communicate with them later .

If it's support rport Mechanism server , It needs to check... In the received request Via Whether the header contains a with no value rport Parameters . If there is , It needs to bring... In the response rport Value , This is related to received The treatment is similar to .

example

Here's an example of sending REGISTER Examples of information , When requesting information Via The header contains... Without value rport Parameters , As shown below ：