Non-UE N2 Messages Transfer Call Flow

This section describes the Non-UE N2 Messages Transfer call flow.

The AMF does not analyze the binary contents of the received message from any of its peer nodes.

Non-UE N2 Messages Transfer Call Flow
Non-UE N2 Messages Transfer Call Flow Description

Step

Description

1

The peer node sends a NonUEN2MsgeTransferRequest to the AMF. The REST-EP receives this request and forwards the message to the AMF service.

2

AMF does the following while handling the warning messages (these messages may contain filters, for example, gNB or TAIs that must match):

  • On receiving the warning message, AMF service checks for protocol errors and returns error response, if there is any.

  • If the warning message contains filters, the AMF forwards the message to all NG-RANS that match the filters.

  • If the warning message doesn’t contain filters, the AMF forwards the message to all NG-RANs connected to this AMF.

  • If the warning message contains filters but no matching NG-RANs, the AMF doesn’t send any message.

3

The AMF sends NonUEN2MsgeTransferResponce to the REST-EP.

  • The AMF saves PWS messages to obtain correlation in responses, if the CBCF requests the responses to be send.

4

The REST-EP sends the response to the peer that sent the request.

5

The AMF service forwards the NonUEN2MsgeTransferRequest to the NGAP-EP. The NGAP-EP uses the parameters of the request to find the list of gNodeB to send these messages.

6

The NGAP-EP forwards the message to gNB with the following scenarios:

  • The NGAP copies the N2 payload without any changes and forwards it to the gNB, when the message has the N2InformationClass set to PWS.

  • The AMF performs the following actions, when the sendRanResp field in PWS information is set to true.

    • Saves the msgIdentifier and the serial number of the message.

    • Saves the notification control block for PWS information.