Previously, AMF would sends PDUSessionResourceSetupRequest
when the following conditions were met:
- gNB didn't send UE Context Request IE of InitialUEMessage
- AMF should send SMF generated TRANSFER message(PDU_RES_SETUP_REQ)
to the gNB
However, in issues #771, the gNB did not accept
PDUSessionResourceSetupRequest. Perhaps the gNB engineer thought
that if gNB needs to send data traffic to the UE, AMF should send
an InitialContextSetupRequest regardless of UE Context Request IE.
This is because gNB requires the kgNB security context
for data connection.
So, in this case, Open5GS-AMF decided to send
an InitialContexSetupRequest regardless of
whether it received UE Context Request IE of InitialUEMessage.