6.1 Initial PDN connection establishment over first access

23.1613GPPNetwork-Based IP Flow Mobility (NBIFOM)Release 17Stage 2TS

6.1.1 Initial PDN connection establishment over 3GPP access

Figure 6.1.1-1: PDN connection establishment over 3GPP access with GTP based S5/S8

In the case of E-UTRAN, the UE performs the PDN connection establishment over EUTRAN access as specified in TS 23.401 [4] clause 5.3.2.1 for Initial Attach, and as specified in TS 23.401 [4] clause 5.10.2 for UE requested PDN connectivity, with the following additions:

Step 1: In the case of initial attach, the UE includes an NBIFOM indication in the PCO in the Attach Request. In the case of UE requested PDN connectivity, the UE sends PDN Connectivity Request, including an NBIFOM indication in the PCO.

– In addition, UE requests the NBIFOM mode of this PDN connection in the PCO according to the consideration based on clause 5.4.4 Mode Selection.

Step 2-3: In the Create Session Request, the MME and SGW notify PDN GW of their support for NBIFOM.

Step 4: If dynamic PCC is applied for the PDN connection, during the IP-CAN session establishment, the PDN GW informs the PCRF about the UE and network support of NBIFOM capability, the requested NBIFOM mode, IP-CAN type and the RAT type; and if the UE and the network support NBIFOM, the H-PCRF informs the PDN GW about its decision on whether to allow NBIFOM for the PDN connection. If PCC does not apply, the PDN GW takes the local decision on whether to allow NBIFOM for the given PDN connection.

Step 5: The PDN GW indicates the NBIFOM support and the NBIFOM mode in the PCO and includes the Charging Id for the PDN Connection in the Create Session Response. The PCO is forwarded to the UE as described in TS 23.401 [4].

For UTRAN, the UE performs the initial PDN connection establishment over GERAN/UTRAN access as specified in TS 23.060 [5] clause 9.2.2.1A (PDP context activation using S4) and addition of a new PDN connection as specified in TS 23.060 [5] clause with the following additions:

Step 1: As described in TS 23.060 [5] clause 9.2.2.1, the UE sends Activate PDP context Request, including an NBIFOM indication as well as the requested NBIFOM mode in the PCO. UE requests the NBIFOM mode of this PDN connection in the PCO according to the consideration based on clause 5.4.4 Mode Selection.

Step A-B: As described in TS 23.060 [5], clause 9.2.2.1A, the SGSN and S-GW inform the PDN GW their support of NBIFOM:

– If PCC applies, during the IP-CAN session establishment procedure, the PDN GW informs the PCRF about the UE and network support of NBIFOM capability, about the requested NBIFOM mode and about the IP-CAN type and RAT type; and if the UE and network support NBIFOM, the H-PCRF informs the PDN GW about its decision on whether to allow NBIFOM for the PDN Connection. If PCC does not apply, the PDN GW takes a local decision on whether to allow NBIFOM for the PDN Connection.

Step 9: As described in TS 23.060 [5] clause 9.2.2.1A, the PDN GW indicates the NBIFOM support and the NBIFOM mode in the PCO and includes the Charging Id for the PDN Connection in the Create Session Response. The PCO is forwarded to the UE as described in TS 23.401 [4].

6.1.2 PDN connection establishment over S2a

This clause describes PDN connection establishment for S2a with single-connection mode and S2a with multi-connection mode.

6.1.2.1 Single-connection mode

This procedure is used to establish a PDN Connection over trusted WLAN access in single-connection mode.

Figure 6.1.2.1-1: PDN connection establishment procedure over TWAN access for SCM

For SCM, a new PDN connection is established as described in TS 23.402 [2] clause 16.2 for Initial Attach, with the following additions:

– During the EAP authentication, the UE negotiates single-connection mode and requests EPC access. The UE also indicates NBIFOM support in the PCO provided during the EAP authentication. The UE also provides the requested NBIFOM mode in the PCO according to the conditions for NBIFOM mode selection in clause 5.4.4.

– The TWAN includes an NBIFOM support indication in the Create Session Request to the PDN GW.

– If dynamic PCC is applied for the PDN Connection, the PDN GW initiates an IP-CAN session establishment procedure. As part of this procedure the PDN GW informs the PCRF about the UE and network support of NBIFOM capability, about the requested NBIFOM mode and about the IP-CAN type. If the UE and network support NBIFOM, the PCRF informs the PDN GW about its decision on whether to allow NBIFOM for the PDN Connection. If dynamic PCC is not applied, the PDN GW takes a local decision on whether to allow NBIFOM for the PDN Connection.

– The PDN GW includes the Charging Id for the PDN Connection separately in the Create Session Response to the TWAN. The PDN GW indicates the network support of NBIFOM in the PCO in the Create Session Response. The PCO is forwarded to the UE as described in clause 16.2, TS 23.402 [2].

6.1.2.2 Multi-connection mode

This procedure is used to establish a PDN Connection over trusted WLAN access in multi-connection mode.

Figure 6.1.2.2-1: PDN connection establishment procedure over TWAN access for MCM

For MCM, the UE attaches to TWAN using the procedure described in steps 1-15 in clause 16.2.1 of TS 23.402 [2] and negotiates for multi-connection mode. If multi-connection mode is authorized by the network, the UE performs the PDN Connection establishment procedure in clause 16.8.1 of TS 23.402 [2] with the following additions:

– The UE indicates NBIFOM support in PCO in the WLCP PDN Connection Request to the TWAN. The UE also provides the requested NBIFOM mode in PCO according to the conditions for NBIFOM mode selection in clause 5.4.4.

– The TWAN includes an NBIFOM support indication in the Create Session Request sent to the PDN GW.

– If dynamic PCC is applied for the PDN Connection, in the PDN GW initiates an IP-CAN session establishment procedure. As part of this procedure the PDN GW informs the PCRF about the UE and network support of NBIFOM capability, about the requested NBIFOM mode and about the IP-CAN type. If the UE and network support NBIFOM, the PCRF informs the PDN GW about its decision on whether to allow NBIFOM for the PDN Connection. If dynamic PCC is not applied, the PDN GW takes a local decision on whether to allow NBIFOM for the PDN Connection.

– The PDN GW includes the Charging Id for the PDN Connection separately in the Create Session Response to the TWAN. The PDN GW indicates the NBIFOM support in the PCO in the Create Session Response. The PCO is forwarded to the UE as described in clause 16.2, TS 23.402 [2].

6.1.3 PDN connection establishment over S2b

This procedure is used to establish a PDN Connection over untrusted WLAN access.

Figure 6.1.3-1: PDN connection establishment over WLAN access

The procedure is the same as described in clause 7.2.4 of TS 23.402 [2], with the following additions:

– The UE uses Configuration Payload in IKEv2 signalling to indicate its support for NBIFOM. The UE also provides in the IKEv2 Configuration Payload the requested NBIFOM mode for this PDN connection according to the conditions on NBIFOM mode selection in clause 5.4.4.

– If the ePDG supports NBIFOM, the ePDG shall indicate its NBIFOM capability in the Create Session Request sent to the PDN GW. The ePDG also transfers the UE support for NBIFOM and the UE request for the NBIFOM operation mode to the PDN GW.

– If dynamic PCC is applied for the PDN Connection, the PDN GW initiates an IP-CAN session establishment procedure. As part of this procedure the PDN GW informs the PCRF about the UE and network support of NBIFOM capability, about the requested NBIFOM mode and about the IP-CAN type. If the UE and network support NBIFOM, the PCRF informs the PDN GW about its decision on whether to allow NBIFOM for the PDN Connection. If PCC is not applied, the PDN GW takes a local decision on whether to allow NBIFOM for the PDN Connection.

– The PDN GW includes the Charging Id for the PDN Connection separately in the Create Session Response to the ePDG The PDN GW indicates the NBIFOM support in the APCO in the Create Session Response.

– The ePDG shall forward the negotiated result of NBIFOM support to the UE via Configuration Payload in IKEv2 signalling.