Section: 6.2.17 Handling of edge computing enhancements
Content: EAS discovery, EAS rediscovery and ECS address provisioning provide enhanced edge computing support in 5GS (see 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A]). If the network supports the session breakout connectivity model or distributed anchor connectivity model to enable edge computing enhancements and the UE generated DNS message is to be handled by an edge application server discovery function (EASDF) for EAS discovery as specified in 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A], the SMF selects the EASDF and it provides its IP address to the UE as the DNS server to be used for the PDU session in the Extended protocol configuration options IE during the UE-requested PDU session establishment procedure as described in subclause 6.4.1.3. NOTE 1: EASDF selection is outside the scope of the present document. If the network supports the session breakout connectivity model to enable edge computing enhancements and the UE generated DNS message is to be handled by a local DNS server for EAS discovery as specified in 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A], the SMF selects the local DNS server, obtains its IP address and can provide the IP address of the local DNS server to the UE as the DNS server to be used for the PDU session in the Extended protocol configuration options IE during the UE-requested PDU session establishment procedure or the network-requested PDU session modification procedure as described in subclauses 6.4.1.3 and 6.3.2.2, respectively. NOTE 2: Local DNS server selection and the acquisition of its IP address is outside the scope of the present document. If the UE supports EAS rediscovery and the SMF decides to trigger the EAS rediscovery as specified in 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A], the SMF initiates a network-requested PDU session modification procedure to provide the EAS rediscovery information to the UE as described in subclauses 6.3.2.2. Upon receipt of the EAS rediscovery information, the UE provides the received information to the upper layers. NOTE 3: The upper layers of the UE uses the EAS rediscovery information to trigger the EAS discovery procedure to get the new EAS information as specified in 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A]. If the UE supports ECS address provisioning over NAS as specified in 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A], the UE indicates its support of ECS configuration information provisioning over NAS in the Extended protocol configuration options IE either during the UE-requested PDU session establishment procedure as described in subclause 6.4.1.2 or while in S1 mode as described in 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [15], respectively. If the UE indicated support of ECS configuration information address provisioning over NAS, the SMF can provide the ECS configuration information in the Extended protocol configuration options IE during the network-requested PDU session modification procedure, UE-requested PDU session establishment procedure or the UE-requested PDU session modification procedure as described in subclauses 6.3.2.2, 6.4.1.3 and 6.4.2.3, respectively. NOTE 4: The SMF can obtain the ECS configuration information based on the local configuration, the UE's location, the UE's subscription information, or any combination of them. If the UE supports the edge DNS client (EDC) as specified in 3GPP TS 23.548[ 5G System Enhancements for Edge Computing; Stage 2 ]  [10A], the UE indicates its support of EDC in the Extended protocol configuration options IE during the UE-requested PDU session establishment procedure as described in subclause 6.4.1.2 or the UE-requested PDU session modification procedure as described in subclause 6.4.2.2. If the UE indicates support of EDC, the SMF can indicate in the Extended protocol configuration options IE during the UE-requested PDU session establishment procedure as described in subclause 6.4.1.3 or the network-requested PDU session modification procedure as described in subclause 6.3.2.2, that the network allows the use of EDC for the applications which are mapped onto the PDU session and explicitly requested the use of EDC, or that the network requires the use of EDC for all applications mapped onto the PDU session.