First attach the flow chart of session establishment in 23502: the flow chart
listed in the above specification has the advantages of
① large and complete,
but there are many small regrets, mainly
① not combining with specific scenarios to analyze
② not joining the main protocol Message and parameter description
③Hidden the NRF network element selection process
④The text on the arrow in the figure is actually not the name of the message. For example, the third step is Nsmf_PDUSession_CreateSMContext Request, but the actual message name is HTTP2 POST:/nsmf- pdusession/v1/sm-contexts, this is easy to cause confusion in learning, so it is not very friendly to novices (this is how I came here at the beginning, after reading the agreement, I found that combining wireshark to capture packets is still in the cloud).
The following process is based on actual conditions and is closer to the actual network of domestic operators
certainGuangzhou 5GUser toBeijingBusiness trip. After waking up at 7 in the morning, start the machine and complete the registration under the Beijing AMF service area. I got on the taxi at 8 o'clock and clicked on an APP to scan news to trigger the PDU session establishment process.
The process will be accessed through gNB access in Beijing, Beijing AMF to complete session management message transparent transmission, Beijing SMF to complete session management control, Beijing NRF to complete network element selection, and Beijing data center UPF to complete the forwarding of user data messages to Beijing Internet exit (Beijing DN), and the UE session management-related contract data is issued by the home city Guangzhou UDM, and the Guangzhou PCF issues the UE session management control strategy.
Reference: 51xuetongxin.com
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