Content for &nbsp; TS 23.558 &nbsp; Word version:&nbsp; 19.0.0

The EEC sends an EAS discovery request to the EES. The EAS discovery request includes the requestor identifier [EECID] along with the security credentials and may include EAS discovery filters, EEC service continuity support, and may also include UE location to retrieve information about particular EAS(s) or a category of EASs, e.g. gaming applications, or Edge Applications Server(s) available in certain service areas, e.g. available on a UE's predicted or expected route. The request may include an EAS selection request indicator.

Upon receiving the request from the EEC, the EES checks if the EEC is authorized to discover the requested EAS(s). The authorization check may apply to an individual EAS, a category of EASs or to the EDN, i.e. to all the EASs. If UE's location information is not already available, the EES obtains the UE location by utilizing the capabilities of the 3GPP core network as specified in clause 8.10.3. If EAS discovery filters are provided by the EEC, but it does not contain Application group profile, the EES identifies the EAS(s) based on the provided EAS discovery filters and the UE location.

When the bundle EAS information is provided, then;

If bundle EAS information includes EAS bundle identifier, the EES identifies all or part of the EAS(s) associated with the same EAS bundle identifier.
If bundle EAS information includes a list of EASIDs, the EES identifies the EASs which are all or part of the EAS bundle.

If the EEC indicates that service continuity support is required, when identifying the EAS, the EES shall take the indication which ACR scenarios are supported by the AC, the EEC, the EES and the EAS and which of these are preferred by the AC into consideration. The EES may select one EAS and determine whether to perform application traffic influence for this AC based on AC's service KPI or EAS's service KPI in desired response time, when the EAS does not perform traffic influence in advance.

When EAS discovery filters are not provided, then:

if available, the EES identifies the EAS(s) based on the UE-specific service information at the EES and the UE location;
EES identifies the EAS(s) by applying the ECSP policy (e.g. based only on the UE location);

When EAS discovery filters contain Application group profile, the EES checks whether information about common EAS and related Application Group ID is available or not. If the common EAS information related to the Application Group ID is:

not available, then based on the policy if EES needs to select the common EAS, the EES identifies an EAS for the Application Group ID based on the provided EAS discovery filters such as KPIs, UE-specific service information or the ECSP policy. Furthermore, the EES stores the common EAS information and related Application Group ID.
available at the EES, then the EES provides information of that EAS as result for EAS discovery.

When the ECS-ER is not available and the EES selects the common EAS, the selected common EAS shall be announced to other EES(s) as per procedure specified in clause 8.19.

When the ECS-ER is available and common EAS information corresponding to the Application Group ID is not available, then the EES identifies one EAS for the group and interacts with the ECS-ER to store the common EAS information as described in clause 8.20.2.3. If common EAS information is already available corresponding to the Application Group ID in the repository, then the ECS-ER returns the common EAS information to the EES as described in clause 8.20.2.3.

Upon receiving the request from the EEC, the EES may also collect edge load analytics from ADAES (as specified in clause 8.8.2 of TS 23.436) or performance data from OAM to find whether the EAS(s) satisfies the Expected AC service KPIs or the Minimum required AC Service KPIs.

Upon receiving the request from the EEC, if the EEC does not indicate EAS Instantiation Triggering Suppress in the EAS Discovery request, the EES may trigger the ECSP management system to instantiate the EAS that matches with EAS discovery filter IEs (e.g. ACID) as in clause 8.12.

Otherwise, upon receiving the request from the EEC, if the EEC indicates EAS Instantiation Triggering Suppress in the EAS Discovery request and the EES supports such capability, the EES determines not triggering the ECSP management system to instantiate the EAS and may determine Instantiable EAS Information for EAS(s) that are instantiable but not yet instantiated and match the EAS discovery filter IEs. Instantiable EAS Information is provided in the EAS Discovery response and includes the EASID(s) and, for each EASID, the status indicating whether the EAS is instantiated or instantiable but not yet instantiated.

If the EEC provides in the EAS discovery request the EAS selection request indicator, the EES selects EAS satisfying the EAS discovery filter or based on other information (e.g. ECSP policy) as described above (if no EAS discovery filter received), and then provides the selected EAS information to the EEC in the discovered EAS list of EAS discovery response.

Figure 8.5.2.3.2-1: EAS discovery subscription

If the processing of the request was successful, the EES sends an EAS discovery response to the EEC, which includes information about the discovered EASs and Instantiable EAS Information. For discovered EASs, this includes endpoint information. Depending on the EAS discovery filters received in the EAS discovery request, the response may include additional information regarding matched capabilities, e.g. service permissions levels, KPIs, AC locations(s) that the EASs can support, ACR scenarios supported by the EAS, etc. The EAS discovery response may contain a list of EASs and Instantiable EAS Information. This list may be based on EAS discovery filters containing a Geographical or Topological Service Area, e.g. a route, included in the EAS discovery request by the EEC. When the discovered EAS is for a certain application group, then the Application Group ID is also included in the response message. If the discovered EAS is registered to another EES, then the EES endpoint of the EES where the discovered EAS is registered is also included in the response message.

When the EES determines to trigger the EAS instantiation, then the response may indicate that the EAS instantiation is in progress so that the detailed EAS profile information will be available later. When EEC receives the EAS instantiation in progress indication, the EEC may send EAS discovery subscription request message or send EAS discovery request message later to the EES for obtaining updated EAS information.

If the EES is unable to determine the EAS information using the inputs in the EAS discovery request, UE-specific service information at the EES or the ECSP policy, the EES shall reject the EAS discovery request and respond with an appropriate failure cause.

If the EEC is not registered with the EES, and ECSP policy requires the EEC to perform EEC registration prior to EAS discovery, the EES shall include an appropriate failure cause in the EAS discovery response indicating that EEC registration is required.

If the UE location and predicted/expected UE locations, provided in the EAS discovery request, are outside the Geographical or Topological Service Area of an EAS, then the EES shall not include that EAS in the discovery response. The discovery response may include EAS(s) that cannot serve the UE at its current location if a predicted/expected UE location was provided in the EAS discovery request.

Upon receiving the EAS discovery response, if the EEC selects an EAS which is instantiated (i.e., an EAS profile was provided), the EEC uses the endpoint information for routing of the outgoing application data traffic to EAS(s), as needed, and may provide necessary notifications to the AC(s). The EEC may use the border or overlap between EAS Geographical Service Areas for service continuity purposes. The EEC may cache the EAS information (e.g. EAS endpoint) for subsequent use and avoid the need to repeat step 1. If the Lifetime IE is included in the response, the EEC may cache the EAS information only for the duration specified by the Lifetime IE.

Upon receiving the EAS discovery response, if the EEC selects an EAS which is instantiable but not yet instantiated (i.e. an EAS profile is not provided), the EEC sends the EAS information provisioning request indicating the selected EASID as in clause 8.15.

If the EAS discovery request fails, the EEC may resend the EAS discovery request, taking into account the received failure cause. If the failure cause indicated that EEC registration is required, the EEC shall perform an EEC registration before resending the EAS discovery request.

8.5.2.3 Subscribe-notify model p. 95

8.5.2.3.1 General p. 95

Clause 8.5.2.3.2 and clause 8.5.2.3.3 together illustrate the EAS discovery procedure based on Subscribe/ Notify model.

Clause 8.5.2.3.4 illustrates the EAS discovery update procedure.

Clause 8.5.2.3.5 illustrates the EAS discovery unsubscribe procedure.

8.5.2.3.2 Subscribe p. 95

Figure 8.5.2.3.2-1 illustrates the EAS discovery subscription procedure between the EEC and the EES. This subscription enables EES to inform EEC of various EAS discovery related events of interest to EEC (e.g. EAS discovery notification and EAS dynamic information).

Pre-conditions:

The EEC has received information (e.g. URI, IP address) related to the EES;
The EEC has received appropriate security credentials authorizing it to communicate with the EES as specified in clause 8.11;
The EES is configured with ECSP's policy for EAS discovery; and
The EEC has optionally acquired a Notification Target Address to be used in its subscriptions to notifications.

Reproduction of 3GPP TS 23.558, Fig. 8.5.2.3.2-1: EAS discovery subscription

The EEC sends an EAS discovery subscription request to the EES. The EAS discovery subscription request includes the EECID along with the security credentials, Event ID, and may include EAS discovery filters and EAS dynamic information filters to subscribe to information about particular EAS(s) or a category of EASs (e.g. gaming applications) or dynamic information about EAS(s).

If the application triggering is supported and required by the EEC, the EEC may include the EEC Triggering request information element instead of the Notification Target Address in the request message.

Upon receiving the request from the EEC, the EES checks if the EEC is authorized to subscribe for information of the requested EAS(s). The authorization check may apply to an individual EAS, a category of EASs or to the EDN, i.e. to all the EASs. The EES may utilize the capabilities (e.g. UE location) of the 3GPP core network as specified in clause 8.10.3. If the request is authorized, the EES creates and stores the subscription for EAS discovery.

Figure 8.5.2.3.3-1: EAS discovery notification

If the processing of the request was successful, the EES sends an EAS discovery subscription response to the EEC, which includes the subscription identifier and may include the expiration time, indicating when the subscription will automatically expire. To maintain the subscription, the EEC shall send an EAS discovery subscription update request prior to the expiration time. If an EAS discovery subscription update request is not received prior to the expiration time, the EES shall treat the EEC as implicitly unsubscribed.

In the case of subscription to an EAS availability change event, if there is no instantiated EAS that matches the requested EAS discovery filters and such EAS is instantiable based on the information about instantiable EASs, the request is treated as successful. If the EEC indicates EAS Instantiation Triggering in the EAS discovery subscription request and the EAS instantiation is not in progress for the requested EASID, the EES may trigger dynamic instantiation of the EAS as specified in the clause 8.12; if the EEC indicates EAS Instantiation Triggering Suppress in the EAS discovery subscription request, the EES determines not triggering the ECSP management system to instantiate the EAS and Instantiable EAS Information (e.g. instantiated, instantiable but not be instantiated yet) is provided; otherwise, the EES does not trigger the EAS instantiation nor returns the Instantiable EAS Information.

In the case of subscription to an EAS dynamic information change event, if the EES is unable to determine the instantiated EAS information using the inputs in the EAS discovery subscription request, UE-specific service information at the EES or the ECSP policy, the EES shall reject the EAS discovery subscription request and respond with an appropriate failure cause.

If the EAS discovery subscription request fails, the EEC may resend the EAS discovery subscription request again, taking into account the received failure cause. If the failure cause indicated that EEC registration is required, the EEC shall perform an EEC registration before resending the EAS discovery subscription request.

8.5.2.3.3 Notify p. 96

Figure 8.5.2.3.3-1 illustrates the EAS discovery notification procedure between the EEC and the EES.

Pre-conditions:

The EEC has subscribed with the EES for the EAS discovery information as specified in clause 8.5.2.3.2.

Reproduction of 3GPP TS 23.558, Fig. 8.5.2.3.3-1: EAS discovery notification

An event occurs at the EES that satisfies trigger conditions for notifying (e.g. to provide EAS discovery information or EAS dynamic information) a subscribed EEC. If UE's location information is not already available, the EES obtains the UE location by utilizing the capabilities of the 3GPP core network as specified in clause 8.10.3. If EAS discovery filters were provided by the EEC during subscription creation, the EES identifies the EAS(s) based on the provided EAS discovery filters and the UE location.

For EAS dynamic information change event, the EES, based on local policy, may use received EAS endpoints from EEC or all registered EAS endpoints to get edge load analytics information from ADAES services (e.g. as specified in clause 8.8 of TS 23.436) to monitor EAS service status like EAS status and EAS schedule.

When the bundle EAS information is provided, then;

If EAS bundle identifier was provided, the EES identifies all or part of the EAS(s) associated with the same EAS bundle identifier.
If a list of EASIDs is provided, the EES identifies the EASs which are all or part of the EAS bundle.

If the EEC indicates that service continuity support is required, the EES shall take the indication which ACR scenarios are supported by the AC and the EEC and which of these are preferred by the AC into consideration.

If EAS discovery filters were not provided, then:

if available, the EES identifies the EAS(s) based on the UE-specific service information at the EES and the UE location;
EES identifies the EAS(s) by applying the ECSP policy (e.g. based only on the UE location);

If EAS discovery filters contain Application group profile, the EES checks whether information about common EAS and related Application Group ID is available or not. If the common EAS information related to the Application Group ID is available at the EES, then the EES provides information of that EAS as result for EAS discovery.

If the UE is located outside the Geographical or Topological Service Area of an EAS, then the EES shall not include this EAS in the EAS discovery notification.

If the application triggering is supported and required by the EEC as indicated in EEC Triggering Request IE of the EAS Discovery Subscription Request, then the EES performs the EEC triggering service as described in the clause 8.16.1 and skips the step 2.

Figure 8.5.2.3.4-1: EAS discovery subscription update

The EES sends an EAS discovery notification to the EEC with the EAS information determined in step 1, which includes information about the discovered EASs and Instantiable EAS Information. For discovered EASs, this includes endpoint information. Depending on the event type and EAS discovery filters received in the EAS discovery subscription request, the notification may include additional information regarding matched capabilities, e.g. service permissions levels, KPIs, AC locations(s) that the EASs can support, ACR scenarios supported by the EAS, etc. The EAS discovery notification may contain a list of EASs and Instantiable EAS Information. This list may be based on EAS discovery filters containing a Geographical or Topological Service Area, e.g. a route, included in the EAS discovery subscription request by the EEC. When the discovered EAS is for a certain application group, then the Application Group ID is also included in the notification message. If the discovered EAS is registered to another EES, then the EES endpoint of the EES where the discovered EAS is registered is also included in the notification message.

Upon receiving the EAS discovery notification, if the EEC selects an EAS which is instantiated (i.e., an EAS profile was provided), the EEC uses the endpoint information for routing of the outgoing application data traffic to EAS(s), as needed, and may provide necessary notifications to the AC(s). The EEC may use the border or overlap between EAS Geographical Service Areas for service continuity purposes. The EEC may cache the EAS information (e.g. EAS endpoint) for subsequent use. If the Lifetime IE is included in the notification, the EEC may cache the EAS information only for the duration specified by the Lifetime IE.

Upon receiving the EAS discovery notification, if the EEC selects an EAS which is instantiable but not yet instantiated (i.e. an EAS profile is not provided), the EEC may send the EAS information provisioning request indicating the selected EASID as in clause 8.15.

8.5.2.3.4 Subscription update p. 98

Figure 8.5.2.3.4-1 illustrates the EAS discovery subscription update procedure between the EEC and the EES.

Pre-conditions:

The EEC has subscribed with the EES for the EAS discovery information as specified in clause 8.5.2.3.2

Reproduction of 3GPP TS 23.558, Fig. 8.5.2.3.4-1: EAS discovery subscription update

The EEC sends an EAS discovery subscription update request to the EES. The EAS discovery subscription update request includes the security credentials and the subscription identifier. It may also include EAS discovery filters, EAS dynamic information filters and/or proposed expiration time for the updated subscription.

Upon receiving the request from the EEC, the EES checks if the EEC is authorized to update the subscription information. The EES may utilize the capabilities (e.g. UE location) of the 3GPP core network as specified in clause 8.10.3. If the request is authorized, the EES updates the stored subscription for EAS discovery.

Figure 8.5.2.3.5-1: EAS discovery unsubscribe

The EES sends an EAS discovery subscription update response to the EEC, which may include the expiration time, indicating when the updated subscription will automatically expire. To maintain the subscription, the EEC shall send an EAS discovery subscription update request prior to the expiration time. If an EAS discovery subscription update request is not received prior to the expiration time, the EES shall treat the EEC as implicitly unsubscribed.

8.5.2.3.5 Unsubscribe p. 98

Figure 8.5.2.3.5-1 illustrates the EAS discovery unsubscribe procedure between the EEC and the EES.

Pre-conditions:

The EEC has subscribed with the EES for notification (e.g. EAS discovery information and EAS dynamic information) as specified in clause 8.5.2.3.2

Reproduction of 3GPP TS 23.558, Fig. 8.5.2.3.5-1: EAS discovery unsubscribe

The EEC sends an EAS discovery unsubscribe request to the EES. The EAS discovery unsubscribe request includes the security credentials of the EEC along with the subscription identifier.

Upon receiving the request, the EES performs an authorization check to verify whether the EEC has authorization to perform the operation. If authorized, the EES cancels the subscription for provisioning as requested in step 1.