vSMF Create Session Procedure
This section provides details about the create session procedure for vSMF.

Step |
Description |
---|---|
1 |
The AMF receives a request from a UE. Based on the local configuration, the AMF locates a vSMF and a list of possible hSMFs to handle the UE request. It creates a CreateSmContext request, and POSTs the message to the vSMF. In the vSMF, based on the presence of an hSMF URI that is not its own, and the SUPI policy configuration of , the vSMF creates a PDU Context for valid UE requests. |
2 |
The vSMF locates and creates a charging association with the appropriate CHF. |
3 |
The vSMF responds to the AMF request with a reference to the created PDU Session. |
4 |
The vSMF sends a PFCP Session Creation request to the vUPF. The vUPF responds with the CN tunnel Information of the created tunnel. |
5 |
The vSMF creates a PDU Session Create Request to send to the hSMF. The CN tunnel information of the vUPF is an IE that is sent to the hSMF. Most of the request parameters from the AMF are copied on to the request to the hSMF. The following parameters from the N1 Message are removed from the request before it's sent to the hSMF:
The UE request from the vSMF to the hSMF is sent asynchronously. This method enables the hSMF to start the EBI assignment procedures through the vSMF when it's processing the create request from the VSMF. |
6 |
If a secondary authentication is required, the hSMF uses the callback URI for the vSMF session and the modify method to send an authentication request payload for the UE. |
7 |
The vSMF sends this message to the AMF, and the AMF responds to the vSMF. |
8 |
The UE responds to the authentication request, which is conveyed by the AMF to the vSMF. |
9 |
The vSMF sends the update to the hSMF. |
10 |
The vSMF responds to the AMF for the Modify Request. |
11 |
If this session can be moved to EPC, the hSMF starts the EBI allocation procedure by invoking the modify method on the vSMF callback URI. |
12 |
The vSMF invokes the assign-ebi method on the AMF, and the AMF sends back the assigned EPS bearer ID to the vSMF. |
13 |
The vSMF responds to the hSMF. |
14 |
If the request is acceptable to the hSMF, it responds with a 201 Created response which includes the subscription information required for the setup of the PDU session in the GNB. The response also contains an N1 payload. |
15 |
The SMF updates the CHF with the parameters from the response from hSMF, including the charging profile setup by the hSMF. |
16 |
The vSMF creates an N1N2MessageTransferRequest to the AMF.
|
17 |
The AMF responds to the N1N2MessageTranfer Request. |
18 |
The GNB responds with an N2 response to the ERAB RESOURCE SETUP REQUEST to the AMF, which the AMF sends in an SmContext Update message to the vSMF. |
19 |
The vSMF requests the vUPF to update the tunnel information of the GNB, the tunnel and other information sent by the hSMF in step 6. The vUPF responds to the vSMF. |
20 |
If required, the vSMF updates the CHF with any additional information. |
21 |
The vSMF responds to the Update request from the AMF. |
22 |
If there are any flows that have failed to setup, the vSMF notifies the hSMF accordingly. |
23 |
The hSMF responds to the vSMF. |