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Content for  TS 23.548  Word version:  18.6.0

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6.7.2.6  N2 Handover with V-SMF insertion/change/removal in HR-SBO casep. 60

This clause defines the procedure for intra-VPLMN and inter-PLMN N2-based handover for HR-SBO PDU Sessions with V-SMF insertion/change/removal. This procedure is based on Inter NG-RAN node N2-based handover with I-SMF insertion/change/removal defined in clause 4.23.7.3 of TS 23.502 by replacing the I-SMF as V-SMF and replacing the SMF as H-SMF.
The procedure assumes the UE has an HR-SBO PDU Session established as described in clause 6.7.2.2 using a source serving PLMN (e.g. involving a source V-SMF) and there is a handover to a same or different serving PLMN (e.g. involving a target V-SMF) with V-SMF change. The procedure also applies to the scenario where source or target serving network (before or after an inter-PLMN handover) is the HPLMN thus V-SMF insertion or removal happens.
Reproduction of 3GPP TS 23.548, Fig. 6.7.2.6-1: N2-based handover with V-SMF insertion/change/removal in HR-SBO case
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The procedure described in clauses 4.23.17 and 4.23.7.3 of TS 23.502 (N2-based handover with I-SMF insertion/change/removal) is performed by replacing I-SMF with V-SMF and SMF with H-SMF with following modifications:
Step 0.
The untrusted AF may subscribe via the H-NEF to the H-PCF or the trusted AF may directly subscribe to the H-PCF, then the H-PCF subscribe to the H-SMF for the event related with a mobility of the PDU Session towards a serving PLMN where local traffic offload is possible, i.e. mobility of the PDU Session either towards HPLMN or towards a VPLMN where HR-SBO is possible i.e. supported and allowed.
Step 1.
Step 1 in Figure 4.23.7.3.2-1 of TS 23.502 (initiation of the N2-based handover).
For an intra VPLMN HO, the source AMF provides the target AMF with whether HR-SBO is allowed for each PDU Session of the UE.
For an inter PLMN HO, the target T-AMF uses local policies related to the SLA with the HPLMN of the UE to determine whether HR-SBO allowed indication is sent to the V-SMF(s) for the PDU Sessions of the UE.
Step 2.
Step 2 in Figure 4.23.7.3.2-1 of TS 23.502 takes place.
If the T-AMF considers that HR-SBO is possible, the T-AMF selects a V-SMF supporting HR-SBO.
Step 2a.
(V-SMF insertion or V-SMF change) step 2 in Figure 4.23.7.3.2-1 of TS 23.502 takes place.
For V-SMF insertion and inter VPLMN V-SMF change case, the T-AMF sends an HR-SBO allowed indication to the target V-SMF in Nsmf_PDUSession_CreateSMContext Request as part of the step 3 of the procedure in Figure 4.23.7.3.2-1 of TS 23.502.
Step 2b.
(V-SMF removal) steps 9 to 12b in Figure 4.23.7.3.2-1 of TS 23.502 take place.
The target AMF sends to H-SMF a Nsmf_PDUSession_CreateSMContext request as in step 9 in Figure 4.23.7.3.2-1 of TS 23.502.
For EAS discovery with EASDF, the H-SMF selects an EASDF in HPLMN and configures the DNS context in this EASDF (Neasdf_DNSContext_Create) and may select and configure UPF(s) in HPLMN.
For EAS discovery with Local DNS Server, the H-SMF selects a Local DNS Server.
Steps 3 to 5 are skipped if the UE moves with V-SMF removal.
Step 3.
(V-SMF insertion or V-SMF change) step 4 or step 5 in Figure 4.23.7.3.2-1 of TS 23.502.
Step 3a.
(V-SMF insertion case) The (target) V-SMF retrieves SM context from H-SMF using Nsmf_PDUSession_Context Request, followed by the Nsmf_PDUSession_Context Response.
Step 3b.
(V-SMF change case) The target V-SMF retrieves SM context from the source V-SMF using Nsmf_PDUSession_Context Request/Response.
In step 3b, if source and target V-SMFs belong to same VPLMN, the SM context includes Authorization Result for HR-SBO, VPLMN Specific Offloading Information and/or corresponding Offload Identifier(s), the SM context also includes (if previously received by source V-SMF from H-SMF in the case of V-SMF change) the HPLMN address information, and the DNS Server address provided by the HPLMN.
The SM context may also include EAS information to be refreshed for EAS re-discovery, i.e. FQDN(s) corresponding to the old target DNAI selected by the source V-SMF (V-SMF change case).
If source and target V-SMFs belong to same VPLMN, the SM context may also include EAS IP replacement information (i.e. source EAS IP address and port number, target EAS IP address and port number) and the target DNAI.
Step 4.
(V-SMF insertion or V-SMF change) The (target) V-SMF selects a new V-EASDF e.g. based on the target UE location. The (target) V-SMF invokes Neasdf_DNSContext_Create including the DNN, S-NSSAI and HPLMN ID to obtain the new V-EASDF address.
In the case of V-SMF insertion, the UE IP address is set to the unspecified address in Neasdf_DNSContext_Create as specified in clause 7.1.2.2.
In the case of V-SMF change with inter PLMN mobility or intra PLMN mobility, the target V-SMF shall select a new V-EASDF if it is configured to use an EASDF for the PDU Session.
To support EAS discovery with local DNS server as described in clause 6.7.2.4, the (target) V-SMF (re-)selects a local DNS server, e.g. based on the target UE location.
Step 5.
(V-SMF insertion or V-SMF change) The (target) V-SMF may perform UL CL/BP and local PSA insertion/change/removal as described in step 2 of Figure 6.7.2.2-1.
Step 6.
The H-SMF (V-SMF removal) or the target V-SMF (V-SMF insertion or V-SMF change) responses to the target AMF with a Nsmf_PDUSession_CreateSMContext Response as in step 8 (V-SMF insertion or V-SMF change) or step 13 in Figure 4.23.7.3.2-1 of TS 23.502 (V-SMF removal).
The handover procedure further continues as defined in steps 14 onwards of Figure 4.23.7.3.2-1 of TS 23.502 and then per clause 4.23.7.3.3 of TS 23.502, with clause 4.23.7.3.3 of TS 23.502 modified as follows:
Step 7.
(V-SMF insertion or V-SMF change) when the T-AMF sends to the Target V-SMF an indication of Handover Complete within Nsmf_PDUSession_UpdateSMContext Request (at step 2 in Figure 4.23.7.3.3-1 of TS 23.502) the target V-SMF invokes Nsmf_PDUSession_Update Request to the H-SMF.
If a V-EASDF or a local DNS server has been selected in step 4, the selected V-EASDF or local DNS server address is provided in the request. The target V-SMF needs not provide the selected V-EASDF or local DNS server address if the target V-SMF is configured to use EAS discovery with V-EASDF using IP replacement mechanism corresponding to clause 6.7.2.5.
If the UE indicated support of refreshing stale EAS information, the V-SMF may also provide an EAS rediscovery indication and EAS information to be refreshed for EAS re-discovery if received in step 3 to the H-SMF.
This Nsmf_PDUSession_UpdateSMContext Request triggers steps 8 to 11.
Step 8.
(V-SMF insertion or V-SMF change): If the UE has changed of serving VPLMN or has moved from HPLMN to a VPLMN, the H-SMF:
  • invokes Nudm_SDM_Get service to get subscription data from UDM by providing serving PLMN ID to get subscription data specific to the Serving PLMN;
  • authorizes the request for HR-SBO based on the SM subscription data (i.e., HR-SBO authorization indication); and
  • If the HR-SBO is authorized, retrieves the VPLMN Specific Offloading Policy from H-PCF.
Step 9.
(V-SMF insertion or V-SMF change): As defined in step 8 in clause 4.23.7.3.3 of TS 23.502, the H-SMF invokes Nsmf_PDUSession_Update Response, providing the same HR-SBO related information as sent by the H-SMF in step 2 of Figure 6.7.2.2-1.
The H-SMF furthermore provides V-SMF with PCO including EAS rediscovery indication and impact field based on the EAS information to be refreshed for EAS re-discovery if received at step 7.
The target V-SMF stores the PCO including the V-EASDF address/local DNS server address, EAS rediscovery, impact field for the UE until it receives an indication of HO completion as described in step 2 in Figure 4.23.7.3.3-1 of TS 23.502 or in step 11.
If the request for HR-SBO is not authorized and a V-EASDF context had been created, the V-SMF deletes the DNS context from the selected V-EASDF, and the subsequent steps related to the HR-SBO in this procedure are skipped.
Step 10.
(V-SMF insertion or V-SMF change): The (target) V-SMF configures the V-EASDF with the DNS handling rules as defined in step 3 of Figure 6.7.2.2-1.
If the (target) V-SMF has interacted with the V-EASDF in step 4, the V-SMF invokes Neasdf_DNSContext_Update Request including UE IP address to complete the configuration of the context in the V-EASDF.
The (target) V-SMF may configure the ULCL/L-PSA selected in the step 5 to forward DNS messages to V-EASDF.
When the V-SMF is configured to use EAS discovery with V-EASDF using IP replacement mechanism as described in clause 6.7.2.5, the (target) V-SMF configures the UL CL/L-PSA in the VPLMN with the IP replacement information (i.e. IP address of the DNS server provided by the HPLMN, the selected V-EASDF IP address and port number and DNS traffic filtering rules related with when IP replacement applies).
Step 11.
(V-SMF insertion or V-SMF change): The target V-SMF sends the PCO for the UE (received at step 9) in a PDU Session Modification Command sent to the UE.
(V-SMF removal): At step 10 in Figure 4.23.7.3.3-1 of TS 23.502, when receiving Nsmf_PDUSession_UpdateSMContext Request (Handover Complete indication), the H-SMF sends the PCO including the V-EASDF or Local DNS Server address selected in step 2b in a PDU Session Modification Command sent to the UE. If the UE indicated support of refreshing stale EAS information, the PCO may include EAS rediscovery indication.
Step 12.
(V-SMF change or removal): When the S-AMF invokes Nsmf_PDUSession_ReleaseSMContext Request to inform the Source V-SMF to release the SM context of the PDU Session, e.g. at step 3a or 11a in Figure 4.23.7.3.3-1 of TS 23.502, the DNS context in the old (V-)EASDF is removed by the (source) V-SMF using Neasdf_DNSContext_Delete service.
(V-SMF insertion): When the target V-SMF sends Nsmf_PDUSession_Update Request with a Handover Complete Indication at step 6 in Figure 4.23.7.3.3-1 of TS 23.502, the DNS context in the old EASDF is removed by the H-SMF using Neasdf_DNSContext_Delete service.
Step 13.
If the AF had subscribed in step 0 and a serving PLMN change occurred towards a PLMN where local traffic offload is possible for the PDU Session, the H-SMF notifies the H-PCF then either via H-NEF or directly notify the AF indicating the target serving PLMN ID and DNN, S-NSSAI of the HPLMN. This may take place as soon as the H-SMF has received an indication of Handover Complete.
Step 14.
EAS discovery procedure by UE may take place:
(V-SMF change or V-SMF insertion): EAS Discovery procedure with V-EASDF for HR-SBO (according to clause 6.7.2.3), with Local DNS for HR-SBO (according to clause 6.7.2.4), or with V-EASDF using IP replacement mechanism (according to clause 6.7.2.5); or
(V-SMF removal): EAS Discovery procedure with EASDF or Local DNS Server (according to clause 6.2.3.2).
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6.7.2.7  Inter V-SMF mobility registration update procedure in HR-SBO casep. 64

This clause defines the procedure for inter V-SMF intra-VPLMN and inter-PLMN mobility registration update procedure for HR-SBO PDU Sessions. This procedure is based on I-SMF insertion/change/removal defined in clauses 4.23.3 and 4.23.4.3 of TS 23.502 by replacing the I-SMF as V-SMF and replacing the SMF as H-SMF.
Reproduction of 3GPP TS 23.548, Fig. 6.7.2.7-1: Inter V-SMF mobility registration update in HR-SBO
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Step 0.
Same as step 0 of Figure 6.7.2.6-1.
Step 1.
The UE establishes a HR-SBO PDU Session as described in clause 6.7.2.2.
Step 2.
The UE initiates Mobility Registration Update procedure to the Target AMF as described in clauses 4.23.3 and 4.2.2.2.2 of TS 23.502. During the registration procedure, the target AMF (in roaming case) receives the SMF selection data including HR-SBO allowed indication per DNN/S-NSSAI from the UDM in the step 14b of the procedure in clause 4.2.2.2.2 of TS 23.502.
Step 3a.
(V-SMF insertion or V-SMF change): at step 17 of clause 4.2.2.2.2 of TS 23.502, the Target AMF selects and inserts a V-SMF supporting HR-SBO and provides the received HR-SBO allowed indication for the established Session for DNN, S-NSSAI in the PDUSession_CreateSMContext Request sent to the target V-SMF.
Step 3b.
(V-SMF removal) in case the Target AMF is an AMF of HPLMN (the UE moves from a VPLMN to HPLMN), in step 3b-1, the Target AMF sends a PDUSession_CreateSMContext Request sent to the H-SMF. In step 3b-2, the H-SMF retrieves SM Context from the V-SMF by invoking Nsmf_PDUSession_Context Request. The H-SMF may select an EASDF in HPLMN and configure the DNS context in this EASDF (Neasdf_DNSContext_Create) and may select and configure UPF(s) in HPLMN as in step 3b-3. For the V-SMF removal case, the steps 4 to 10 are skipped.
Step 4a.
(V-SMF insertion case) The (target) V-SMF retrieves SM context from H-SMF using Nsmf_PDUSession_Context Request/Response, followed by the Nsmf_PDUSession_Context Request/Response.
Step 4b.
(V-SMF change case) The target V-SMF retrieves SM context from the source V-SMF using Nsmf_PDUSession_Context Request/Response indicating HR-SBO support in the Request in the case of an intra-PLMN V-SMF case.
In step 4b, if source and target V-SMFs belong to same VPLMN, the SM context from the source V-SMF includes Authorization Result for HR-SBO, VPLMN Specific Offloading Information and/or corresponding Offload Identifier(s) and (if previously received by source V-SMF from H-SMF) the HPLMN address information, and the DNS Server address provided by the HPLMN.
Step 5.
As in step 4 of Figure 6.7.2.6-1, the (target) V-SMF may invoke Neasdf_DNSContext_Create.
Step 6.
As in step 5 of Figure 6.7.2.6-1, the (target) V-SMF may perform UL CL/BP and local PSA insertion/change/removal.
Step 7.
The target V-SMF invokes Nsmf_PDUSession_Update Request to the H-SMF as in step 7 of Figure 6.7.2.6-1.
Step 8.
As in step 8 of Figure 6.7.2.6-1, the H-SMF invokes Nudm_SDM_Get service, authorizes the request for HR-SBO based on the SM subscription data, and retrieves the VPLMN Specific Offloading Policy from H-PCF in case the HR-SBO is authorized.
Step 9.
As in step 9 of Figure 6.7.2.6-1, once the HR-SBO is authorized, the H-SMF sends the VPLMN Specific Offloading Information in the Nsmf_PDUSession_Update Response message to the target V-SMF.
Step 10.
As in step 9 of Figure 6.7.2.6-1, the (target) V-SMF may configure the V-EASDF based on the received VPLMN Specific Offloading Information.
Step 10a.
The (target) V-SMF may also update the configuration of the V-UPF based on the received VPLMN Specific Offloading Information.
Step 11.
As in step 6 of Figure 6.7.2.6-1, the target V-SMF (in the case of V-SMF removal, the H-SMF) answers to the target AMF with PDUSession_CreateSMContext Response.
Step 12.
The registration procedure continues as defined in clause 4.2.2.2.2 of TS 23.502 from step 18 on.
Step 13.
In the case of V-SMF removal or change, when, at step 17a of clause 4.23.4.3 of TS 23.502, receiving Nsmf_PDUSession_ReleaseSMContext Request from the source AMF, the source V-SMF initiates a Neasdf_DNSContext_Delete if a V-EASDF was used for the PDU Session.
In the case of V-SMF insertion, when at step 9 the H-SMF sends to the V-SMF VPLMN Specific Offloading Information in Nsmf_PDUSession_Update Response, the DNS context in the old EASDF may be removed by the H-SMF using Neasdf_DNSContext_Delete service.
Step 14.
(V-SMF insertion or V-SMF change): The target V-SMF sends the DNS information for the UE (received at step 9) and EAS rediscovery indication via PCO in a PDU Session Modification Command sent to the UE.
(In the case of V-SMF removal): the H-SMF sends the DNS information (received at step 3) for the UE and EAS rediscovery indication via PCO in a PDU Session Modification Command sent to the UE.
Step 15.
As in step 13 of Figure 6.7.2.6-1, notification from H-SMF to the AF either via H-NEF or directly to the AF.
Step 16.
As in step 14 of Figure 6.7.2.6-1: EAS discovery procedure by UE may take place.
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6.7.2.8  N2 Handover without V-SMF change in HR-SBO casep. 67

This clause defines the procedure for intra-VPLMN N2-based handover without V-SMF change for HR-SBO PDU Session. This procedure is based on Inter NG-RAN node N2-based handover without I-SMF change defined in clause 4.23.7.2 of TS 23.502.
The procedure described in clauses 4.23.17, 4.23.7.2, 4.9.1.3.2 and 4.9.1.3.3 of TS 23.502 is performed by replacing I-SMF with V-SMF and SMF with H-SMF with following modifications:
  • Preparation phase, step 3 of clause 4.9.1.3.2: the source AMF provides the target AMF with whether HR-SBO is allowed for each PDU Session of the UE.
  • Preparation phase, after step 4 of clause 4.9.1.3.2:
    For EAS discovery with V-EASDF as described in clause 6.7.2.3, the V-SMF may (re-)select a new V-EASDF or reuse the existing V-EASDF based on the target UE location. The V-SMF may invoke Neasdf_DNSContext_Create including the DNN, S-NSSAI and HPLMN ID to obtain the new V-EASDF address.
    For EAS discovery with local DNS server as described in clause 6.7.2.4, the V-SMF may (re-)select a local DNS server, e.g. based on the target UE location.
  • Preparation phase, steps 5-6 of clause 4.9.1.3.2:
    The V-SMF may perform UL CL/BP and local PSA insertion/change/removal as described in step 2 of Figure 6.7.2.2-1.
  • Execution phase, after step 7 of clause 4.9.1.3.3:
    The V-SMF removes the DNS Context in the old V-EASDF if a new V-EASDF is selected.
  • Execution phase, step 10a of clause 4.23.7.2.3 and 4.9.1.3.3:
    The V-SMF invokes Nsmf_PDUSession_Update Request toward the H-SMF.
    If a V-EASDF or a local DNS server has been selected, the selected V-EASDF or local DNS server address is provided in the request. The V-SMF needs not provide the selected V-EASDF or local DNS server address if the V-SMF is configured to use EAS discovery with V-EASDF using IP replacement mechanism corresponding to clause 6.7.2.5.
    If the UE indicated support of refreshing stale EAS information, the V-SMF may also provide an EAS rediscovery indication and EAS information to be refreshed for EAS re-discovery corresponding to the old target DNAI if it has been inserted by the V-SMF.
    The H-SMF invokes Nsmf_PDUSession_Update Response toward the V-SMF including the PCO for the UE. The PCO may includes V-EASDF or local DNS Server address, EAS rediscovery indication and impact field which is generated based on EAS information to be refreshed for EAS re-discovery.
  • Execution phase, after step 10 of clause 4.9.1.3.3:
    The V-SMF sends the PCO in a PDU Session Modification Command sent to the UE.
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6.7.2.9  Xn Handover with V-SMF change in HR-SBO casep. 68

This clause defines the procedure for Xn handover with intra-PLMN V-SMF change for HR-SBO PDU Session. This procedure is based on Xn based handover with re-allocation of I-SMF defined in clause 4.23.11.3 of TS 23.502.
The procedure described in clauses 4.23.17 and 4.23.11.3 of TS 23.502 is performed by replacing I-SMF with V-SMF and SMF with H-SMF with following modifications:
  • step 4 of clause 4.23.11.3:
    The target V-SMF retrieves SM context from the source V-SMF.
  • The SM context includes Authorization Result for HR-SBO, VPLMN Specific Offloading Information. It may also include Offload Identifier(s).
  • The SM context also includes (if previously received by source V-SMF from H-SMF) the HPLMN address information, and the DNS Server address provided by the HPLMN.
  • The SM context also includes EAS information to be refreshed for EAS rediscovery, i.e. the FQDN(s) corresponding to the old target DNAI if it has been inserted by the source V-SMF.
    The V-SMF selects a new V-EASDF, e.g. based on the target UE location. The V-SMF may invoke Neasdf_DNSContext_Create including the DNN, S-NSSAI and HPLMN ID to obtain the new V-EASDF address.
    To support EAS discovery with local DNS server as described in clause 6.7.2.4, the V-SMF selects a local DNS server, e.g. based on the target UE location.
    The V-SMF may perform UL CL/BP and local PSA insertion as described in step 2 of Figure 6.7.2.2-1.
  • step 6 of clause 4.23.11.3:
    If a V-EASDF or a local DNS server has been selected in step 4, the selected V-EASDF or local DNS server address is provided in the Nsmf_PDUSession_Update Request.
    The target V-SMF needs not provide the selected V-EASDF or local DNS server address if the target V-SMF is configured to use EAS discovery with V-EASDF using IP replacement mechanism corresponding to clause 6.7.2.5.
    If the UE indicated support of refreshing stale EAS information, the target V-SMF may also provide an EAS rediscovery indication and EAS information to be refreshed for EAS re-discovery if received in step 4 to the H-SMF.
  • step 9 of clause 4.23.11.3: the H-SMF includes the same HR-SBO related information as sent by the H-SMF in step 2 of Figure 6.7.2.2-1.
    The H-SMF furthermore provides the target V-SMF with EAS rediscovery indication to be sent to the UE and also impact field based on the EAS information to be refreshed for EAS re-discovery if received at step 6.
    The target V-SMF configures the V-EASDF with the DNS handling rules as defined in step 3 of Figure 6.7.2.2-1.
    If the target V-SMF has interacted with the V-EASDF in step 4, the target V-SMF invokes Neasdf_DNSContext_Update Request including UE IP address to complete the configuration of the context in the V-EASDF.
    The target V-SMF may configure the V-UPF selected in the step 4 to forward DNS messages to V-EASDF.
    When the target V-SMF is configured to use EAS discovery with V-EASDF using IP replacement mechanism as described in clause 6.7.2.5, the V-SMF configures the UPF in the VPLMN with the IP replacement information (i.e. IP address of the DNS server provided by the HPLMN, the selected V-EASDF IP address and port number and DNS traffic filtering rules related with when IP replacement applies).
    The target V-SMF sends the PCO including the V-EASDF address/local DNS server address, EAS rediscovery, impact field for the UE in a PDU Session Modification Command sent to the UE.
  • step 12a of clause 4.23.11.3:
    When the AMF invokes Nsmf_PDUSession_ReleaseSMContext Request to inform the Source V-SMF to release the SM context of the PDU Session, the DNS context in the old V-EASDF is removed by the source V-SMF using Neasdf_DNSContext_Delete service.
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6.7.2.10  Xn Handover without V-SMF change in HR-SBO casep. 69

This clause defines the procedure for Xn handover without V-SMF change for HR-SBO PDU Session. This procedure is based on Xn based handover without change of I-SMF defined in clause 4.23.11.5 of TS 23.502.
The procedure described in clauses 4.23.17 and 4.23.11.5 of TS 23.502 is performed by replacing I-SMF with V-SMF and SMF with H-SMF with following modifications:
  • step 2 of clause 4.23.11.5:
    When the V-SMF receives Nsmf_PDUSession_UpdateSMContext Request, the V-SMF may (re-)select a new V-EASDF or reuse the existing V-EASDF based on the target UE location. The V-SMF may invoke Neasdf_DNSContext_Create including the DNN, S-NSSAI and HPLMN ID to obtain the new V-EASDF address.
    For EAS discovery with local DNS server as described in clause 6.7.2.4, the V-SMF may (re-)select a local DNS server, e.g. based on the target UE location.
    The V-SMF may perform UL CL/BP and local PSA insertion/change/removal as described in step 2 of Figure 6.7.2.2-1.
    The V-SMF invokes Nsmf_PDUSession_Update Request toward the H-SMF.
    If a V-EASDF or a local DNS server has been selected, the selected V-EASDF or local DNS server address is provided in the request. The V-SMF needs not provide the selected V-EASDF or local DNS server address if the V-SMF is configured to use EAS discovery with V-EASDF using IP replacement mechanism corresponding to clause 6.7.2.5.
    If the UE indicated support of refreshing stale EAS information, the V-SMF may also provide an EAS rediscovery indication and EAS information to be refreshed for EAS re-discovery corresponding to the old target DNAI if it has been inserted by the V-SMF.
    The V-SMF is responsible of when to remove the context in the old V-EASDF.
  • step 6 of clause 4.23.11.5:
    The Nsmf_PDUSession_Update Response sent by the H-SMF towards the V-SMF includes the PCO for the UE. The PCO may include V-EASDF or local DNS Server address, EAS rediscovery indication and impact field which is generated based on EAS information to be refreshed for EAS re-discovery.
    The V-SMF sends the PCO in a PDU Session Modification Command sent to the UE.
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