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Content for  TS 23.558  Word version:  17.4.0

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8.9  EEC Context and EEC Context relocationp. 147

8.9.1  Generalp. 147

EEC Context contains information related to an EEC which is used by EESs to provide the Edge Enabler Layer services. The EEC Context may include information about the EEC-hosting UE and the ACs to which the EEC provides services. The EEC Context information may be collected and maintained at the EES in an EDN while the respective ACs are connected to EASs in that EDN.
EEC Context relocation procedures allow the EEC Context information to be shared between EESs (via EDGE-9 interactions).
The EEC Context information may contain List of EDGE-1 subscriptions (i.e., list of subscription IDs for an EEC). The corresponding EDGE-1 subscription information includes EEC ID, Event ID, subscription ID, 3GPP CN subscription information (optional), notification target address (optional) and filter information (optional).
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8.9.1.1  EEC Context handling at EEC registrationp. 148

An EEC Context shall be created for each registered EEC, after a successful registration, by the receiver EES, as follows:
  • If the EEC registration request does not include a previously assigned EEC Context ID value, the receiver EES creates an EEC Context as described in clause 8.2.8. The receiver EES shall assign an EEC context ID and set the source EES Endpoint to its own Endpoint. The EEC ID and UE Identifier shall be set based on the corresponding registration request parameters.
  • If the EEC registration request contains an EEC context ID and source EES Endpoint, the receiver (i.e., target) EES performs an EEC Context Pull relocation (clause 8.9.2.2). After a successful EEC Context relocation, the target EES updates the source EES Endpoint with its own Endpoint. The target EES may preserve the EEC Context ID received in the request or assign a new EEC Context ID, subject to EES implementation and local policies.
    If the EEC Context relocation is not successful, the target EES creates an EEC Context as described in clause 8.2.8. The target EES shall assign an EEC context ID and set the source EES Endpoint to its own endpoint. The EEC ID and UE ID shall be set based on the corresponding registration request parameters.
    After a successful EEC Context Relocation procedure is performed at EEC (re-)registration to a target EES, the source EES shall determine to be stale the EEC Context identified by the EEC Context ID included in the request (i.e., relocated) and the EEC to be de-registered.
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8.9.1.2  EEC Context handling at EEC registration updatep. 148

An EEC Context shall be updated when EEC Registration update requests targeting the corresponding EEC ID are received.

8.9.1.3  EEC Context handling at EEC de-registrationp. 148

An EEC Context, including the list of Service Session Context(s) information, shall be determined to be stale after a successful EEC de-registration procedure.

8.9.1.4  EEC Context handling at Application Context Relocationp. 148

The EEC Context provided to a target EES in an EEC Context Pull relocation or an EEC context Push relocation shall be stored at the target EES, as follows:
  • If an EEC context with the same EEC ID, EEC Context ID and source Endpoint already exists at the target EES, the EEC Context is updated.
  • If an EEC context with the same EEC ID, EEC Context ID and source Endpoint does not exist at the target EES, the EEC Context is stored.
After a successful EEC Context Relocation procedure is performed at ACR, the source EES shall determine to be stale the element(s) of the list of Service Session Context(s) information included in the request (i.e., relocated). If all Service Session Context(s) information in the EEC Context are stale, the EEC Context is determined to be stale and the EEC to be de-registered.
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8.9.1.5  Other EEC Context handlingp. 148

Elements of the list of Service Session Context(s) information shall be created by the EES when it determines that a registered EAS is providing services to an AC on the served EEC.
Elements of the list of Service Session Context(s) information shall be determined to be stale when the EES determines that a registered EAS is no longer providing services to an AC on the served EEC.
An EEC Context shall be updated as follows:
  • When EEC Context(s) are created, either after a registration request or based on EEC Context relocation procedure, the EES shall check whether the UE Identifier corresponds to an existing EEC Context and update the EEC Context accordingly.
  • When EEC subscription requests corresponding to the EEC ID are processed, the "List of EDGE-1 subscriptions" shall be updated accordingly
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8.9.2  Proceduresp. 149

8.9.2.1  Generalp. 149

The following procedures are supported for EEC Context relocation:
  • EEC Context Push; and
  • EEC Context Pull.

8.9.2.2  EEC Context Pull relocationp. 149

An EEC Context is relocated via an EEC Context Pull request initiated by the target EES.
Figure 8.9.2.2-1 illustrates the EEC Context Pull.
Pre-conditions:
  1. The source EES has provided the EEC with an EEC Context ID; and
  2. The target EES has received the EEC Context ID, source EES Endpoint.
Copy of original 3GPP image for 3GPP TS 23.558, Fig. 8.9.2.2-1: EEC Context Pull procedure
Figure 8.9.2.2-1: EEC Context Pull procedure
(⇒ copy of original 3GPP image)
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Step 1.
The target EES requests an EEC Context from the source EES. The request includes EEC Context ID.
Step 2.
Upon receiving the request from the target EES, the source EES validates the request and verifies the security credentials of the requester. The source EES uses the EEC Context ID provided to identify and authorize the EEC Context to be relocated.
Step 3.
The source EES sends a successful EEC Context response. The target EES stores the received EEC Context.

8.9.2.3  EEC Context Push relocationp. 150

An EEC Context is relocated via an EEC Context Push request initiated by the source EES.
Pre-conditions:
  1. The source EES has provided the EEC with an EEC Context ID.
Copy of original 3GPP image for 3GPP TS 23.558, Fig. 8.9.2.3-2: EEC Context relocation procedure initiated by source EES
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Step 1.
The source EES determines to forward EEC Context for relocation to a target EES. The source EES determines the target and the EEC Context to be forwarded.
Step 2.
The source EES sends EEC Context Push request to the target EES including the EEC Context determined.
Step 3.
Upon receiving the request from the source EES, the target EES validates the request and verifies the security credentials. The target EES uses the EEC Context ID provided to authorize the EEC Context to be stored and managed. Then the target EES sends an EEC Context response indicating success. The T-EES performs implicit registration and creates the registration ID for the registration and includes it in the EEC context push response message for S-EAS decided ACR or S-EES executed ACR scenarios. The S-EES stores the registration details, and when required, notifes the EEC about registration details while sending ACR information notification.
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8.9.3  Information flowsp. 150

8.9.3.1  Generalp. 150

The following information flows are specified for EEC Context relocation:
  • EEC Context Pull request and response; and
  • EEC Context Push request and response.

8.9.3.2  EEC Context Pull requestp. 150

Table 8.9.3.2-1 describes information elements in the EEC Context Pull request between two EES.
Information element Status Description
EES IDMUnique identifier of the requesting EES.
Security credentialsMSecurity credentials resulting from a successful authorization for the edge computing service.
EEC Context IDMUnique identifier of the EEC Context used to authorize the transfer.
List of Service Session Contexts requestedOList of Service Session Context IEs requested to be pulled
> EAS IDMIdentifier of the EAS providing the application services
> EAS EndpointMEndpoint information of the EAS.
> EEC IDOUnique identifier of the EEC.
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8.9.3.3  EEC Context Pull responsep. 151

Table 8.9.3.3-1 describes information elements in the EEC Context Pull response between two EESs.
Information element Status Description
Successful responseOIndicates that the request was successful.
>EEC ContextOEEC Context, mandatory if the request was successful
Failure responseOIndicates that the request failed.
> CauseOIndicates the cause of request failure, mandatory if the request failed.
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8.9.3.4  EEC Context Push requestp. 151

Table 8.9.3.4-1 describes information elements in the EEC Context Push request between two EESs.
Information element Status Description
EES IDMUnique identifier of the requesting EES.
Security credentialsMSecurity credentials resulting from a successful authorization for the edge computing service.
EEC ContextMEEC Context
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8.9.3.5  EEC Context Push responsep. 151

Table 8.9.3.5-1 describes information elements in the EEC Context Push request between two EES.
Information element Status Description
> registration ID (see NOTE)OIdentifier of the registration for the EEC.
> expiration time (see NOTE)OIndicates the expiration time of the EEC registration.
Successful responseOIndicates that the request was successful.
Failure responseOIndicates that the request failed.
> CauseOIndicates the cause of request failure, mandatory if the request failed.
NOTE:
This IE shall be included if implicit registration is performed by T-EES.
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8.9.4  APIsp. 152

8.9.4.1  Generalp. 152

Table 8.9.4.1-1 illustrates the EEC context management.
API Name API Operations Operation Semantics Consumer(s)
Eees_EECContextPullRequestRequest/ResponseEES
Eees_EECContextPushRequestRequest/ResponseEES
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8.9.4.2  Eees_EECContextPull APIp. 152

8.9.4.2.1  Generalp. 152
This clause describes the Eees_EECContextPull API and its operations.
8.9.4.2.2  Eees_EECContextPull_Request operationp. 152
API operation name:
Eees_EECContextPull_Request
Description:
The consumer requests for the EEC context from the EES.
Inputs:
Outputs:
See clause 8.9.2.2 for details of usage of this operation.

8.9.4.3  Eees_EECContextPush APIp. 152

8.9.4.3.1  Generalp. 152
This clause describes the Eees_EECContextPush API and its operations.
8.9.4.3.2  Eees_EECContextPush_Request operationp. 152
API operation name:
Eees_EECContextPush_Request
Description:
The consumer pushes the EEC context to another EES.
Inputs:
Outputs:
See clause 8.9.2.3 for details of usage of this operation.

8.10  Utilizing 3GPP core network capabilitiesp. 152

8.10.1  Generalp. 152

The functional entities of the Edge Enabler Layer can utilize the 3GPP core network capabilities (i.e. 5GC, EPC) to fulfill the needs of the edge service operations. This clause specifies the details of the 3GPP core network capabilities consumed by each functional entity.

8.10.2  Capabilities utilized by ECSp. 153

When required, the ECS may utilize:
  • user plane path management events by subscribing with the 3GPP core network for the user plane path management event notifications of the UE as described in TS 23.501 and TS 23.502; and
  • the location information from the API exposed by 3GPP core network, e.g. SCEF/NEF/SCEF+NEF or LCS (Location Service) as specified in TS 23.682, TS 23.502, TS 23.271, TS 36.305, TS 23.273 and TS 38.305 to obtain the UE's location from the 3GPP Core Network.
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8.10.3  Capabilities utilized by EESp. 153

When required, the EES may utilize:
  • AF traffic influence functionality, including the user plane path management event notifications of the UE, from the 3GPP core network as described in TS 23.501 and TS 23.502;
  • the location information from the API exposed by 3GPP core network, e.g. SCEF/NEF/SCEF+NEF or LCS (Location Service) as specified in TS 23.682, TS 23.502, TS 23.271, TS 36.305, TS 23.273 and TS 38.305 to obtain the UE's location from the 3GPP Core Network;
  • capabilities exposed by the 3GPP core network, e.g. NEF or PCF, to establish an AF session with QoS, and QoS related event notifications subscribed with the 3GPP core network as specified in TS 23.501, TS 23.502 and TS 23.503;
  • capabilities exposed by the 3GPP core network, e.g. NEF or NWDAF, to analyse UE expected behaviour as specified in TS 23.288; and
  • the monitoring capability exposed by the 3GPP core network as specified in TS 23.501 and TS 23.502.
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8.11  EEC Authentication/Authorizationp. 153

8.11.1  Generalp. 153

The architecture for enabling edge applications supports EEC authentication/authorization.
After the successful EEC authentication/authorization, the EEC acquires a valid security credential for EEC related procedures including service provisioning procedure, EEC registration procedure, EAS discovery procedure and ACR procedure. Detailed procedures are specified in TS 33.558.

8.12  Dynamic EAS instantiation triggeringp. 153

8.12.1  Generalp. 153

The EES may trigger the EAS instantiation dynamically due to e.g., EAS discovery request, UE mobility, upon receiving EEC Registration request containing AC profile.
Upon receiving the EAS discovery request with EAS discovery filter from the EEC or the S-EES during the procedures for EAS discovery or ACR, the EES may fail to discover and select the EAS that matches the UE location and the requesting application characteristics specified in Table 8.5.3.2-2 due to no EAS is available or instantiated. The EES may trigger the EAS management system to instantiate the EAS serving the AC in the EDN before returning the EAS information to the EEC or S-EES, based on the pre-configured dynamic EAS instantiation information about which EAS can be dynamically instantiated at the associated EDN.
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