16 Network slice capability enablement
23.4343GPPFunctional architecture and information flowsRelease 18Service Enabler Architecture Layer for Verticals (SEAL)TS
16.1 General
The network slice capability enablement is a SEAL service that offers network slice capability enablement capabilities, such as support for vertical application to slice re-mapping (which can be defined as the mapping of the UEs running a vertical application to different slice), to one or more vertical applications. In particular, network slice capability enablement uses a network-based mechanism to apply the slice re-mapping based on the network slice capability enablement server configuration, where the network slice capability enablement server acting as AF influences the URSP rules for the application traffic per UE by providing a guidance on the route selection parameters (including the S-NSSAI and DNN mapping).
NOTE: The network slice capability enablement server, acts as an AF within the trusted domain (MNO-owned, or trusted third party).
16.2 Functional model
16.2.1 General
The functional model for the network slice capability enablement is based on the generic functional model specified in clause 6.2. It is organized into functional entities to describe a functional architecture which addresses the support for network slice capability enablement aspects for vertical applications. Since the slicing is a feature which considers the Uu interfaces, only the on-network functional model is specified in this clause.
16.2.2 Functional model description
Figure 16.2.2-1 depicts the network slice capability enablement architecture in the non-roaming case, using the reference point representation showing how various entities interact with each other.
Figure 16.2.2-1: Architecture for network slice capability enablement – reference points representation
The network slice capability enablement client communicates with the network slice capability enablement server over the NSCE-UU reference point. The network slice capability enablement client provides the support for network slice capability enablement functions to the VAL client(s) over NSCE-C reference point. The VAL server(s) communicates with the network slice capability enablement server over the NSCE-S reference point. It is assumed that the network slice capability enablement server is deployed at the 5G system domain. The network slice capability enablement server, acting as AF, may communicate with the 5G Core Network functions via NEF (N33) reference point (for interactions with PCF, NSACF, etc.). The network slice capability enablement server may interact with OAM system over NSCE-OAM reference point, as consumer in both NSaaS and NoP model defined in the clause 4.1.6 and 4.1.7 TS 28.530[43] (for Network Slice Provisioning capabilities, Performance Assurance, Fault Supervision etc.).
NOTE: OAM interfaces and/or network slice information can be exposed to an authorized (trusted) third-party (NSCE) only after a contract has been signed between the MNO and this third-party. Whether and how CAPIF/EGMF can be used to expose management services (MnS) is up to SA5 decision.
Figure 16.2.2- illustrates the architecture for interconnection between NSCE servers.
Figure 16.2.2-2: Interconnection between NSCE servers
The NSCE server could interact with another NSCE server over NSCE-E reference point.
16.2.3 Functional entities description
16.2.3.1 General
The functional entities for network slice capability enablement SEAL service are described in the following subclauses.
16.2.3.2 Network slice capability enablement server
The network slice capability enablement server functional entity provides the application layer enablement of the network slicing aspects to support the VAL applications. Such enablement supports the network slice related operations such as the mapping or migration of one or more vertical applications to one or more network slices (from a set of network slices, as provided by the 3GPP network system) as described in procedure in clauses 16.3.2.3 and 16.3.2.4. Such adaptation assumes that the UE is subscribed to more than one slice and is done via providing a guidance to update the URSP rules at the 5GS (denoted in clause 16.3.3 as network-based mechanism). More operations are described in TS 23.435[40].
16.2.3.3 Network slice capability enablement client
The network slice capability enablement client functional entity acts as the application client for the slice enablement. The network slice capability enablement client interacts with the network slice capability enablement server to trigger network slice related operations such as adaptation due to an application requirement change. This trigger may be due to an application QoS requirement change, a service operation change. The NSCE client may receive a network slice / DNN re-mapping notification from the NSCE server. The NSCE client may optionally notify the VAL client on the network slice / DNN re-mapping.
16.2.4 Reference points description
16.2.4.1 General
The reference points for the functional model for network slice capability enablement are described in the following subclauses.
16.2.4.2 NSCE-UU
The interactions related to network slice capability enablement functions between the network slice capability enablement server and the network slice capability enablement client are supported by NSCE-UU reference point. This reference point utilizes Uu reference point as described in 3GPP TS 23.501 [10].
16.2.4.3 NSCE-C
The interactions related to network slice capability enablement functions between the VAL client(s) and the network slice capability enablement client within a VAL UE are supported by the NSCE-C reference point. The NSCE client may receive application requirement change, application client information (such as its KQI) over NSCE-C. Further, the NSCE client may provide a notification on the network slice adaptation upon successful adaptation of the slice to application mapping.
16.2.4.4 NSCE-S
The interactions related to network slice capability enablement functions between the VAL server(s) and the network slice capability enablement server are supported by the NSCE-S reference point. This reference point is an instance of CAPIF-2 reference point as specified in 3GPP TS 23.222 [8].
16.2.4.5 N33
The reference point N33 supports the interactions between the network slice capability enablement server and the NEF and is specified in 3GPP TS 23.501 [10]. N33 is used for the network-based mechanism for slice re-mapping, where NSCE server acting as AF influences the URSP rules for the application traffic per UE by providing a guidance on the route selection parameters (including the S-NSSAI and DNN mapping), as specified in TS23.502 clause 4.15.6.10, TS 23.503 clause 6.6.2.2, TS 23.548 clause 6.2.4.
16.2.4.6 NSCE-E
The interactions between the NSCE servers are generically referred to as NSCE-E reference point. This reference point supports information collection from other NSCE servers.
16.2.4.7 NSCE-OAM
The interface between the NSCE server and the OAM system are generically referred to as NSCE-OAM reference point. This reference point supports provioning of management service as defined in clause 6.1, TS 28.531[41].
Editor’s note: How NSCE-OAM reference point can be realized by consuming the services exposed by EGMF/CAPIF is currently studied by SA5.
16.3 Procedures and information flows for network slice capability enablement
16.3.1 General
This subclause describes the procedure for network slice adaptation while more procedures for network slice capability enablement are defined in TS 23.435[40].
16.3.2 Network slice adaptation for VAL application
16.3.2.1 General
This subclause describes the procedure for network slice adaptation at the Network Slice Capability Enablement (NSCE) server, based on a request from a VAL server to adapt the network slice for the VAL application. This request is handled between the NSCE server and the NSCE client per each VAL UE of the VAL application.
16.3.2.2 Information flows
16.3.2.2.1 Network slice adaptation request
Table 16.3.2.2.1-1 describes the information flow network slice adaptation request from the VAL server to the NSCE server.
Table 16.3.2.2.1-1: Network slice adaptation request
|
Information element |
Status |
Description |
|
VAL service ID |
M |
The VAL service ID of the VAL application for which the network slice adaptation may corresponds to. |
|
List of VAL UE IDs |
M |
List of the VAL UE IDs within the VAL service for which the slice adaptation request corresponds |
|
Requested slice information |
O |
Indication of the new slice which is requested. The slice information can be either the S-NSSAI or the ENSI (as specified in TS 33.501, for AF outside 3GPP MNO domain). |
|
Requested DNN |
O |
Indication of the new DNN which is requested. |
|
Requested Adaptation threshold |
O (NOTE 1) |
The threshold of network slice adaptation |
|
>Requested adaptation threshold of the delay of network slice |
O |
The network slice delay defined clause 5.1.1.1, 5.1.1.2, 5.1.1.3, in TS 28.552[45] and key performance indicators in clause 6.3, in TS 28.554 [46], and network slice related analytics report in clause 8.4.2.4.3, in TS 28.104[47]. |
|
NOTE 1: The NSCE is requested to adapt UE to the requested network slice only when the current network slice status crosses the requested threshold. |
||
16.3.2.2.2 Network slice adaptation response
Table 16.3.2.2.2-1 describes the information flow network slice adaptation response from the NSCE server to the VAL server.
Table 16.3.2.2.2-1: Network slice adaptation response
|
Information element |
Status |
Description |
|
Result |
M |
Result includes success or failure of the network slice adaptation with the underlying network. |
|
Cause |
O |
Indicates the cause of failure |
16.3.2.2.3 Network slice adaptation trigger
Table 16.3.2.2.3-1 describes the information flow Network slice adaptation trigger from the NSCE client to the NSCE server.
Table 16.3.2.2.3-1: Network slice adaptation trigger
|
Information element |
Status |
Description |
|
VAL UE ID(s) |
M |
The VAL UE ID(s) within the VAL service, for which the network slice adaptation trigger applies |
|
VAL service ID |
M |
The VAL service ID of the VAL application for which the network slice configuration may corresponds to. |
|
Requested S-NSSAI |
M |
Indication of the new S-NSSAI which is requested. |
|
Requested DNN |
O |
Indication of the new DNN which is requested. |
|
Request application requirements |
O |
The application-related request parameters |
|
>Requested time window |
O |
Indication of the new scheduled time window that is requested |
|
>Requested location criteria |
O |
Indication of the new location criteria that is requested |
|
>Requested access type reference |
O |
Indication of the new access type (3GPP, non-3GPP or multi-access) preference that is requested. |
|
>Requested UE IP address preservation indicator |
O |
Indication that UE IP address preservation is requested |
16.3.2.2.4 Network slice adaptation trigger response
Table 16.3.2.2.4-1 describes the information flow network slice adaptation trigger response from the NSCE server to the NSCE client and optionally to the VAL client.
Table 16.3.2.2.4-1: Network slice adaptation trigger response
|
Information element |
Status |
Description |
|
Result |
M |
Result includes success or failure of the network slice adaptation. |
|
Cause |
O |
Indicates the cause of failure |
16.3.2.3 Procedure for VAL server-triggered and network-based network slice adaptation for VAL application
Figure 16.3.2.3-1 illustrates the VAL server-triggered and network-based procedure where the NSCE server supports the network slice adaptation with the underlying 3GPP system for the VAL UEs of the VAL application.
Figure 16.3.2.3-1: Network slice adaptation for VAL application
1. The VAL server sends a network slice adaptation request to the NSCE server for the VAL application (and the VAL UEs within the VAL application). This request may be in the form of exact requested network slice (and optionally DNN) for all the VAL UEs of the VAL application; or indication that the VAL application needs to be remapped to a different network slice (and optionally DNN). The request optionally includes the adaptation threshold of network slice adaptation as defined in Table 16.3.2.2.1-1.
2. [Optional]NSCE server collects the network slice status information, including network slice performance measurements in clause 5.1.1.1, clause 5.1.1.2, clause 5.1.1.3, in TS 28.552[45] and key performance indicators in clause 6.3, in TS 28.554 [46], and network slice related E2E latency analytics report in clause 8.4.2.4.3, in TS 28.104[47] from network slice management functions by utilizing MnS of create MOI operation defined in clause 11.1 and MnS of streaming data reporting service or file data reporting service defined in clause 11.5 and 11.6, TS 28.532[44].
3. The NSCE server processes the request and triggers the network slice configuration per VAL UE within the VAL Application. If network slice status from step 2 is considered, the NSCE server analyses the network slice status information before triggering the network slice configuration. If the threshold is crossed for the current network slice of adaptation and the objective network slice satisfy the requests, NSCE server triggers the network slice configuration per VAL UE within the VAL Application.
4. The NSCE server acting as AF provides the updated S-NSSAI and DNN per VAL UE. In particular, NSCE server sends this information to the PCF via NEF as part of the AF-driven guidance for URSP determination to 5G system (as specified in TS23.502 clause 4.15.6.10, TS 23.503 clause 6.6.2.2, TS 23.548 clause 6.2.4). This guidance may update the route selection parameters to indicate different sets of PDU Session information (DNN, S-NSSAI) that can be associated with applications matching the application traffic.
NOTE: NSCE server provides the updated S-NSSAI/DNN as a suggestion/guidance to PCF; however it is up to PCF to decide whether to perform the slice/DNN re-mapping
5. Upon successful adaptation of the route selection parameters, the NSCE server provides a network slice adaptation response to the VAL server, providing information on the fulfilment of the network slice adaptation request per VAL application.
16.3.2.4 Procedure for VAL UE-triggered and network-based network slice adaptation for VAL application
Figure 16.3.2.4-1 illustrates the VAL UE-triggered and network-based procedure where the NSCE server supports the network slice adaptation with the underlying 3GPP system for the VAL UEs of the VAL application.
Pre-condition:
– The NSCE client has connected to the NSCE server;
Figure 16.3.2.4-1: Network slice adaptation for VAL application
1. The VAL client provides a new application requirement to the NSCE client, indicating a new service profile for the VAL application. This may be in the form of a change at the application QoS requirements, location requirements, time window requirement, access type preference(e.g., 3GPP, non-3GPP or multi access) service operation change, or other application-related parameters.
2. The NSCE client sends a network slice adaptation trigger to the NSCE server for the VAL application. This trigger may be in the form of exact requested network slice (and optionally DNN) for the VAL UE of the VAL application; or indication that the VAL application needs to be remapped to a different network slice (and optionally DNN). The trigger may also include additional application requirements based on step1, e.g., the requested location criteria, time window.
NOTE 1：How the requested network slice is known by the NSCE client is out of scope of this release.
3. The NSCE server processes the request and triggers the network slice configuration per VAL UE within the VAL Application.
NOTE 2：Whether and how the NSCE server triggers the network slice adaptation for all the VAL UEs within the VAL Application is out of scope of this release.
NOTE 3: How the NSCE server decides to trigger the network slice configuration is implementation dependent.
4. The NSCE server acting as AF provides the updated S-NSSAI, application requirements and DNN per VAL UE. In particular, NSCE server sends this information to the PCF via NEF as part of the AF-driven guidance for URSP determination to 5G system (as specified in TS23.502 clause 4.15.6.10, TS 23.503 clause 6.6.2.2, TS 23.548 clause 6.2.4). This guidance may update the route selection parameters to indicate different sets of PDU Session information (DNN, S-NSSAI, application requirements) that can be associated with applications matching the application traffic. 5GC uses this information to update the URSP to the affected UE(s).
NOTE 4: NSCE server provides the updated S-NSSAI/DNN as a suggestion/guidance to PCF; however it is up to PCF to decide whether to perform the slice/DNN re-mapping
5. The NSCE server sends the response to the NSCE client indicating success or failure.
16.4 SEAL APIs for network slice capability enablement
16.4.1 General
Editor’s note: The definition of SEAL APIs for NSCE-UU is FFS
Table 16.4.1-1 illustrates the SEAL APIs for network slice capability enablement.
Table 16.4.1-1: List of SEAL APIs for network slice capability enablement
|
API Name |
API Operations |
Known Consumer(s) |
Communication Type |
|
SS_NetworkSliceAdaptation |
Network_slice_adaptation |
VAL server |
Request /Response |
16.4.2 SS_NetworkSliceAdaptation API
16.4.2.1 General
API description: This API enables the VAL server to communicate with the network slice capability enablement server for network slice adaptation over NSCE-S.
16.4.2.2 Network_Slice_Adaptation
API operation name: Network_Slice_Adaptation
Description: Requesting for network slice adaptation.
Known Consumers: VAL server.
Inputs: See subclause 16.3.2.2.1
Outputs: See subclause 16.3.2.2.2
See subclause 16.3.2.3 for the details of usage of this API operation.