6.3.3 Updates to procedures specified in TS 23.402 [4]
23.2143GPPArchitecture enhancements for control and user plane separation of EPC nodesRelease 17TS
6.3.3.1 Procedures with GTP based S2b establishment
This clause defines interactions between the CP and UP function during the following procedures:
– GTP based S2b for roaming, non-roaming and LBO (clause 7.2.4 of TS 23.402 [4]).
– Emergency services over GTP based S2b (clause 7.2.5 of TS 23.402 [4]).
– UE-initiated connectivity to additional PDN from Un-trusted Non-3GPP IP Access with GTP (clause 7.6.3 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The new PGW-C selects a new PGW-U and creates an Sx session.
Figure 6.3.3.1-1: Interaction between CP and UP function with GTP based S2b establishment
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C shall select new PGW-U as specified in clause 5.12. The PGW-C sends an Sx Session Establishment Request to the selected PGW-U for creating an Sx session for the UE.
3. The PGW-U allocates F-TEIDu for the default bearer. The PGW-U sends an Sx Session Establishment Response to the PGW-C confirming the successful creation of the Sx session. It includes the F-TEIDu it has allocated for the default bearer.
4. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.2 Procedures with GTP based S2a establishment
This clause defines interactions between the CP and UP function during the following procedures:
– UE-Initiated Connectivity to PDN in WLAN on GTP S2a (clause 16.8.1 of TS 23.402 [4]).
– WLAN on GTP S2a for roaming, LBO and non-roaming scenarios (clause 16.2.1 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The new PGW-C selects a new PGW-U and creates an Sx session.
Figure 6.3.3.2-1: Interaction between CP and UP function with GTP based S2a establishment
1-2. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
3. The PGW-C shall select new PGW-U as specified in clause 5.12 The PGW-C sends an Sx Session Establishment Request to the selected PGW-U for creating Sx session for the UE.
4. The PGW-U allocates F-TEIDu for the default bearer. The PGW-U sends an Sx Session Establishment Response to the PGW-C confirming the successful creation of the Sx session. It includes the F-TEIDu it has allocated for the default bearer.
5-7. The HSS/AAA is also made aware of the PGW-C identity at this time. The relevant steps of the procedure as specified in the figure above are then executed.
The following steps are relevant only for "WLAN on GTP S2a for roaming, LBO and non-roaming scenarios" where TWAG using the layer 3 attach request (i.e. a DHCPv4 message) is sent by the UE as the attach trigger. These steps are executed only if steps 3-7 shown in figure 16.2.1-1 are omitted where TWAP sends the layer 2 attach trigger to the TWAG.
8. The PGW-C shall select new PGW-U as specified in clause 5.12. The PGW-C sends an Sx Session Establishment Request to the selected PGW-U for creating Sx session for the UE.
9. The PGW-U allocates F-TEIDu for the bearer. The PGW-U sends an Sx Session Establishment Response to the PGW-C confirming the successful creation of the Sx session. It includes the F-TEIDu it has allocated for the default bearer.
10-11. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.3 Procedures with GTP based S2b release
This clause defines interactions between the CP and UP function during the following procedures:
– UE/ePDG-initiated detach procedure with GTP on S2b (clause 7.4.3.1 of TS 23.402 [4]).
– HSS/AAA-initiated detach procedure with GTP on S2b (clause 7.4.4.1 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The PGW-C releases the existing Sx session from the PGW-U.
Figure 6.3.3.3-1: Interaction between CP and UP function with release of GTP based S2b
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C sends an Sx Session Termination Request to the PGW-U to release the Sx session.
3. The PGW-U sends an Sx Session Termination Response to the PGW-C confirming the release of the Sx session.
4. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.4 Procedures with GTP based S2a release
This clause defines interactions between the CP and UP function during the following procedures:
– UE/TWAN Initiated Detach and UE/TWAN requested PDN Disconnection on GTP S2a (clause 16.3.1.1 of TS 23.402 [4]).
– UE/TWAN-Initiated Detach in WLAN on GTP S2a (clause 16.7.1.1 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The PGW-C releases the existing Sx session from the PGW-U.
Figure 6.3.3.4-1: Interaction between CP and UP function with release of GTP based S2a
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C sends an Sx Session Termination Request to the PGW-U to release the Sx session.
3. The PGW-U sends an Sx Session Termination Response to the PGW-C confirming the release of the Sx session.
4. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.5 Procedures with dedicated bearer activation by PGW
This clause defines interactions between the CP and UP function during the following procedures:
– Dedicated S2b Bearer Activation Procedure with GTP on S2b (clause 7.10 of TS 23.402 [4]).
– Dedicated S2a Bearer Activation Procedure with GTP on S2a (clause 16.5 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The PGW-C modifies the existing Sx session for activating new dedicated bearer.
Figure 6.3.3.5-1: Interaction between CP and UP function with dedicated bearer activation by PGW
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C initiates dedicated bearer activation procedure based on the PCC decision provision (QoS policy) message received from the PCRF. It uses received QoS policy to assign the EPS Bearer QoS, i.e., it assigns the values to the bearer level QoS parameters QCI, ARP, GBR and MBR. The PGW-C sends an Sx Session Modification Request to the existing PGW-U for activating new dedicated bearer for the UE.
3. The PGW-U shall allocate TEIDs for the new bearer(s). The PGW-U sends an Sx Session Modification Response to the PGW-C confirming the successful modification of the Sx session. It shall include the TEIDs it has allocated for the new bearer(s).
4. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.6 Procedures with bearer deactivation by PGW
This clause defines interactions between the CP and UP function during the following procedures:
– PDN GW Initiated Bearer Deactivation with GTP on S2b (clause 7.9.2 of TS 23.402 [4]).
– PDN GW Initiated Bearer Deactivation with GTP on S2a (clause 16.4.1 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The PGW-C modifies the existing Sx session for deactivating the dedicated bearer.
Figure 6.3.3.6-1: Interaction between CP and UP function with bearer deactivation by PGW-C
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C initiates bearer deactivation procedure based on IP-CAN modifications encountered by the PCRF when the dynamic PCC is deployed. The PGW-C sends an Sx Session Modification Request to the existing PGW-U for deactivating the dedicated bearer for the UE.
3. The PGW-U de-allocates the TEIDs for the dedicated bearer and sends an Sx Session Modification Response to the PGW-C confirming the successful modification of the Sx session.
4. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.7 Procedures with bearer modification
This clause defines interactions between the CP and UP function during the following procedures:
– S2b Bearer Modification Procedure with GTP on S2b (clause 7.11.1 of TS 23.402 [4]).
– HSS Initiated Subscribed QoS Modification (clause 7.11.2 of TS 23.402 [4]).
– PDN GW-initiated S2a Bearer Modification Procedure with GTP on S2a (clause 16.6.1 of TS 23.402 [4]).
– HSS Initiated Subscribed QoS Modification (clause 16.6.2 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The PGW-C modifies the existing Sx session for modification of the existing bearer.
Figure 6.3.3.7-1: Interaction between CP and UP function with bearer modification
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C initiates dedicated bearer modification procedure based on the PCC decision provision (QoS policy) message received from the PCRF. It uses this QoS policy to determine that a service data flow shall be aggregated to or removed from an active bearer or that the authorized QoS of a service data flow has changed. The PGW-C sends an Sx Session Modification Request to the existing PGW-U for modification of the existing bearer for the UE.
3. The PGW-U updates the Sx parameters and sends an Sx Session Modification Response to the PGW-C confirming the successful modification of the Sx session.
4. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.8 Procedures with handover from non-3GPP access
This clause defines interactions between the CP and UP function during the following procedures:
– Handover from Trusted Non-3GPP IP Access to E-UTRAN with GTP on S2a or S2b and GTP on S5/S8 interfaces (clauses 8.2.1.1 and 16.11 of TS 23.402 [4]).
– Handover from Trusted Non-3GPP IP Access to UTRAN/GERAN with GTP on S2a and GTP based S5/S8 (clauses 8.2.1.3 and 16.11 of TS 23.402 [4]).
– Handover from Untrusted Non-3GPP IP Access to E-UTRAN with GTP on S2b and GTP on S5/S8 interfaces (clause 8.6.1.1 of TS 23.402 [4]).
– Handover from Untrusted Non-3GPP IP Access to UTRAN/GERAN with GTP on S2b and GTP on S5/S8 interfaces (clause 8.6.1.2 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The SGW-C selects a SGW-U and creates an Sx session.
– The SGW-C modifies the existing Sx session for modification of the bearer.
– The PGW-C selects a PGW-U and creates an Sx session.
– The PGW-C modifies the existing Sx session for modification of the bearer.
Figure 6.3.3.8-1: Interaction between CP and UP function with handover from non-3GPP access
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The SGW-C shall select SGW-U as specified in clause 5.12 when the request with a Handover Indication information. The SGW-C sends Sx Session Establishment Request to the selected SGW-U for creating Sx session for the UE.
3. The SGW-U allocates F-TEIDu for all received bearers. The SGW-U sends Sx Session Establishment Response to the SGW-C confirming the successful creation of the Sx session. It includes the F-TEIDu it has allocated for each and every bearer.
4. The relevant steps of the procedure as specified in the figure above are executed. Since Handover Indication is included, the PGW-C may execute a PCEF-Initiated IP‑CAN Session Modification Procedure with the PCRF.
5. The PGW-C sends an Sx Session Modification Request to the PGW-U for modifying the Sx session for the UE.
6. The PGW-U allocates F-TEIDu for all received bearers. The PGW-U sends an Sx Session Modification Response to the PGW-C confirming the successful modification of the Sx session. It includes the F-TEIDu it has allocated for each and every bearer.
7. The relevant steps of the procedure as specified in the figure above are executed.
8. The SGW-C sends an Sx Session Modification Request after Radio and Access bearers are established at the SGW-C.
9. The SGW-U sends an Sx Session Modification Response to the SGW-C confirming the successful modification of the Sx session.
10. The relevant steps of the procedure as specified in the figure above are executed.
11. The PGW-C sends an Sx Session Modification Request to prompt the PGW-U to tunnel packets from non 3GPP IP access to 3GPP access system and immediately start routing packets to the SGW-U for the default and any dedicated EPS bearers established.
12. The PGW-U sends an Sx Session Modification Response to the PGW-C.
13. The relevant steps of the procedure as specified in the figure above are executed.
6.3.3.9 Procedures with handover from 3GPP access
This clause defines interactions between the CP and UP function during the following procedures:
– Handover from 3GPP Access to Untrusted Non-3GPP IP Access with GTP on S2b (clause 8.6.2.1 of TS 23.402 [4]).
– Handover in single-connection mode from 3GPP access to Trusted WLAN on GTP S2a for roaming and non-roaming scenarios (clause 16.10.1.1 of TS 23.402 [4]).
During the above procedures following is the nature of interactions between the CP and UP function:
– The new PGW-C selects a new PGW-U and creates an Sx session.
Figure 6.3.3.9-1: Interaction between CP and UP function with handover from 3GPP access
1. Procedure as listed in this step is initiated as specified in the relevant clauses of this specification. The relevant steps of the procedure as specified in the figure above are executed.
2. The PGW-C allocates F-TEIDu for each and every bearer. Then the PGW-C sends an Sx Session Establishment Request to the selected PGW-U for modifying the Sx session for the UE.
3. The PGW-U allocates F-TEIDu for all received bearers. The PGW-U sends an Sx Session Establishment Response to the PGW-C confirming the successful modification of the Sx session. It includes the F-TEIDu it has allocated for each and every bearer.
4. The relevant steps of the procedure as specified in the figure above are executed.