Content for  TS 23.316  Word version:  18.5.0

If the PDU Session Modification procedure is initiated by the UE, the UE shall send a PDU Session Modification Request message to AMF as specified step 1 in clause 4.3.2.2 of TS 23.502. The message shall be sent to W-AGF via W-CP signalling connection. The W-AGF shall transparently forward the PDU Session Modification Request to AMF/SMF.

The steps 1a (from AMF) to 1e and steps 2-3 as per the PDU Session Modification procedure in clause 4.3.3.2 of TS 23.502 are executed.

The AMF sends N2 PDU Session Resource Modify Request (N2 SM information received from SMF, NAS message) message to the W-AGF. This step is the same as step 4 in clause 4.3.3.2.

The W-AGF may issue W-CP resource modification procedure (out of scope of 3GPP) with the 5G-RG that is related with the information received from SMF. Based on the N2 SM information received from the SMF, the W-AGF may perform following:

[Conditional] The W-AGF may decide to create a new W-UP resource for the new QoS Flow(s).

[Conditional] The W-AGF may decide to add or remove QoS Flow(s) to/from an existing W-UP resource.

[Conditional] The W-AGF may decide to delete an existing W-UP resource, e.g. when there is no QoS Flow mapped to this W-UP resource.

The W-AGF acknowledges N2 PDU Session Resource Modify Request by sending a N2 PDU Session Resource Modify Response Message to the AMF to acknowledge the success or failure of the request.

Step 7 as per the PDU Session Modification procedure in clause 4.3.3.2 of TS 23.502 is executed.

The W-AGF sends the PDU Session Modification Command to 5G-RG (if received in step 3) and receives the response message from 5G-RG. Steps 4a/4c and step 7 may happen consecutively. Steps 7b map happen before step 4b/4d.

The W-AGF forwards the NAS message to the AMF.

All the steps after step 10 in clause 4.3.3.2 of TS 23.502 are executed according to the general PDU Session Modification procedure.

One or more PDU Sessions are already established for the 5G-RG using the procedure described in clause 7.3.1.

The 5G-RG sends a PDU session release request (N1 SM container (PDU Session Release Request), PDU Session ID) to the AMF via the W-AGF as defined in clause 4.3.4 of TS 23.502.

The steps 1a (from AMF) to 3 according to the PDU Session Release procedure defined in clause 4.3.4.2 of TS 23.502 are executed.

This step is the same as step 4 in clause 4.3.4.2 of TS 23.502.

Upon receiving AN session release request message from the AMF, the W-AGF can trigger the release of the corresponding W-UP resource with procedure out of scope of 3GPP.

This step is the same as step 6 in clause 4.3.4.2 of TS 23.502.

Step 7 according to the PDU Session Release procedure defined in clause 4.3.4.2 of TS 23.502 are executed.

The W-AGF delivers the NAS message (N1 SM container (PDU Session Release Command), PDU Session ID, Cause) to the 5G-RG.

The 5G-RG sends a NAS message (N1 SM container (PDU Session Release Ack), PDU Session ID) to the W-AGF.

This step is the same as step 9 in clause 4.3.4.2 of TS 23.502.

All steps after step 9 in the PDU Session Release procedure defined in clause 4.3.4.2 of TS 23.502 are executed.

[Optional] FN-RG sends an IP address/prefix request to the W-AGF via the L2 connection established in clause 7.2.1.3.

After the registration procedure is completed, the W-AGF may establish PDU session(s) on behalf of the FN-RG. The trigger for W-AGF to initiate a PDU establishment process is defined in BBF TR-456 [9], WT-457 [10] and CableLabs WR-TR-5WWC-ARCH [27]. The W-AGF generates a PDU session ID and derives the parameters for the PDU Session (PDU Session type, S-NSSAI, DNN, SSC mode, etc.) based on signalling received from the FN-RG (DHCP, IPv6 RS, etc.), on local configuration, and on information received from the 5GC (e.g. during the Registration procedure or when received URSP rules) and stored on the W-AGF. If W-AGF has received a DHCPv4/DHCPv6 request from the FN-RG, it may request a PDU Session with deferred IP address allocation. The W-AGF sends a NAS PDU Establishment Request to the AMF. This request contains the PDU Session ID, and may contain a Requested PDU Session Type, a Requested SSC mode, 5GSM Capability PCO, SM PDU DN Request Container, Number of Packet Filters. In the case of PDU Session Type IPv6 or IPv4v6, the PDU Session Establishment Request may contain an interface identifier of the FN-RG IPv6 link local address associated with the PDU Session. The W-AGF sends NAS PDU Establishment Request in a N2 Uplink NAS transport message (NAS message, User location information, W-AGF identities). The W-AGF identities contains a list of Identifiers (i.e. a FQDN and/or IP address(es)) of N3 terminations at W-AGF and can be used by SMF in step 8 in clause 4.3.2.2.1 of TS 23.502 as input to select an UPF.

The PDU session request is processed in the 5GC as per steps 2-11 of clause 4.3.2.2.1 of TS 23.502. These steps are for UPF selection and resource reservation/allocation in the UPF. With regard to TS 23.502, an additional parameter is sent from AMF to SMF i.e. the list of Identifiers (i.e. a FQDN and/or IP address(es)) of N3 terminations at W-AGF received by the AMF from the W-AGF. The SMF can use it in step 8 for UPF selection as per clause 4.3.2.2.1 of TS 23.502. In the case of PDU Session Type IPv6 or IPv4v6, in step 11 of clause 4.3.2.2.1 of TS 23.502:

• The PDU Session Establishment Accept contains the SMF IPv6 link local address associated with the PDU Session if the RAT Type in the Nsmf_PDUSession_CreateSMContext request equals to wireline access.
• The PDU Session Establishment Accept contains the interface identifier of the FN-RG IPv6 link local address if provided in step 1. Otherwise a SMF allocated FN-RG interface identifier is provided.

The SMF responds via AMF as defined in step 11 of clause 4.3.2.2.1 of TS 23.502 with an N2 PDU Session Resource Setup Request that includes QoS profile(s), PDU Session ID, PDU Session Establishment Accept and the N3 tunnel endpoint information for the UPF. The differences with step 11/12 in clause 4.3.2.2.1 of TS 23.502 are:

• The W-AGF shall ignore RSN if received from 5GC.

Based on its own policies, configuration and based on the QoS flows, QoS parameters received in the previous step, the W-AGF shall determine what W-UP resources are needed for the PDU session. The W-AGF may, as defined in BBF TR-456 [9], WT-457 [10] and CableLabs WR-TR-5WWC-ARCH [27], perform Access specific resource reservation with the AN, that is, it sets up the W-UP resources for the PDU session.

The W-AGF allocates AN N3 tunnel information for the PDU Session and includes the AN N3 tunnel endpoint information in the N2 PDU Session Resource Setup Response message to the AMF.

The PDU session setup procedure is completed in 5GC. All steps after step 13 as specified in TS 23.502 Figure 4.3.2.2.1-1 are executed.

If W-AGF requested deferred IP address allocation in step 1 and this was accepted by the network, the W-AGF sends on the user Plane of the PDU Session any DHCP or RS message received beforehand from the FN-RG to the 5GC to obtain the IP address/prefix.

W-AGF completes the IP address/prefix allocation with the FN-RG via the established L2 connection. If W-AGF did not request deferred IP address allocation in step 1a, the IP address/prefix sent back to the FN-RG is the UE IP address/prefix delivered in NAS message in step 2b. If W-AGF requested deferred IP address allocation in step 1a, the IP address/prefix sent back to the FN-RG is the UE IP address/prefix delivered via deferred IP address allocation procedures in step 6a.