Method and device for edge application server discovery

1. A method performed by an edge application server discover function (EASDF) entity, the method comprising:

receiving a context message comprising a domain name system (DNS) message processing rule from a session management function (SMF);

receiving a DNS query message from a user equipment (UE);

processing the DNS query message based on the DNS message processing rule;

transmitting the DNS query message to a DNS server based on the DNS message processing rule;

receiving a DNS response message comprising an edge application server (EAS) internet protocol (IP) address from the DNS server after transmitting the DNS query message;

transmitting, to the SMF, a report message related to the DNS response message based on the DNS message processing rule; and

transmitting the DNS response message to the UE,

wherein the DNS message processing rule comprises an identifier of the DNS message processing rule, an IP address range related to the DNS response message, and a reporting type indicating reporting-once of a DNS message corresponding to the IP address range.

2. The method of claim 1 , further comprising:

receiving, from an edge application service domain repository (EDR) EAS domain configuration information comprising at least one of a plurality of DNS server addresses, a plurality of enhanced DNS client subnet (ECS) options, a plurality of data network access identifiers (DNAIs), or a plurality of edge computer area names (ECANs) for each fully qualified domain name (FQDN).

3. The method of claim 1 , wherein the context message further comprises at least one of UE identifier, UE internet protocol (IP) address, Ethernet medium access control (MAC) address of the UE, or subscription permanent identifier (SUPI).

4. The method of claim 1 , wherein the DNS query message further comprises at least one of fully qualified domain name (FQDN) related to the EAS or 4 he an IP address of the UE.

5. The method of claim 1 , wherein the processing of the DNS query message further comprises:

classifying the DNS query message based on an ECS option and/or the DNS message processing rule;

determining whether to add the ECS option to the DNS query message; and

determining the DNS server to which the processed DNS query message is transmitted.

6. The method of claim 1 , wherein the DNS server comprises at least one of a central DNS (C-DNS) server or a local DNS (L-DNS) server.

7. The method of claim 1 , wherein the processing of the DNS query message further comprises:

determining whether a first UE IP address included in the DNS query message matches a second UE IP address included in the context message;

in case that the first UE IP address does not match the second UE IP address, identifying whether a default DNS server exists; and

in case that the default DNS server exists, determining the DNS server as the default DNS server.

8. The method of claim 7 , wherein the processing of the DNS query message further comprises:

in case that the first UE IP address matches the second UE IP address, determining whether a first fully qualified domain name (FQDN) included in the DNS query message and a second FQDN matching an FQDN expressed in regular expression are associated with an EAS domain configuration information provided from an EDR;

in case that the first FQDN and the second FQDN are not associated with the EAS domain configuration information, identifying whether the default DNS server exists; and

in case that the default DNS server exists, transmitting the DNS query message to the default DNS server.

9. The method of claim 1 ,

wherein the report message comprises EAS information related to the DNS response message based on the reporting type in the DNS message processing rule, and

wherein the EAS information is used in the SMF to determine an insertion of a local UPF (user plane function).

10. The method of claim 9 , further comprising:

receiving, from the SMF, an update message comprising a changed DNS message processing rule.

11. The method of claim 1 ,

wherein the DNS message processing rule further comprises information related to FQDN (fully qualified domain name).

12. An edge application server discover function (EASDF) entity comprising:

a transceiver; and

a processor configured to control the transceiver to:

receive a context message comprising a domain name system (DNS) message processing rule from a session management function (SMF),

receive a DNS query message from a user equipment (UE),

process the DNS query message based on the DNS message processing rule,

transmit the processed DNS query message to a DNS server,

receive, from the DNS server, a DNS response message comprising an edge application server (EAS) internet protocol (IP) address after transmitting the processed DNS query message,

transmit, to the SMF, a report message related to the DNS response message based on the DNS message processing rule, and

transmit the DNS response message to the UE,

wherein the DNS message processing rule comprises at least one of an identifier of the DNS message processing rule, an IP address range, and a reporting type indicating reporting-once of a DNS message corresponding to the IP address range.

13. The EASDF entity of claim 12 , wherein the processor is further configured to:

receive, from an edge application service domain repository (EDER) EAS domain configuration information comprising at least one of a plurality of DNS server addresses, a plurality of enhanced DNS client subnet (ECS) options, a plurality of data network access identifiers (DNAIs), or a plurality of edge computer area names (ECANs) for each fully qualified domain name (FQDN).

14. The EASDF entity of claim 12 , wherein the context message further comprises at least one of UE identifier, UE internet protocol (IP) address, Ethernet medium access control (MAC) address of the UE, or subscription permanent identifier (SUPI).

15. The EASDF entity of claim 12 , wherein the DNS query message further comprises at least one of fully qualified domain name (FQDN) related to the EAS or an IP address of the UE.

16. The EASDF entity of claim 12 , wherein, to process the DNS query message, the processor is further configured to:

classify the DNS query message based on an ECS option and/or the DNS message processing rule;

determine whether to add the ECS option to the DNS query message; and

determine the DNS server to which the processed DNS query message is transmitted.

17. The EASDF entity of claim 12 , wherein the DNS server comprises at least one of a central DNS (C-DNS) server or a local DNS (L-DNS) server.

18. The EASDF entity of claim 12 , wherein, to process the DNS query message, the processor is further configured to:

determine whether a first UE IP address included in the DNS query message matches a second UE IP address included in the context message;

in case that the first UE IP address does not match the second UE IP address, identify whether a default DNS server exists; and

in case that the default DNS server exists, determine the DNS server as the default DNS server.

19. The EASDF entity claim 12 ,

wherein the report message comprises EAS information related to the DNS response message based on the DNS message processing rule, and

wherein the EAS information is used in the SMF to determine an insertion of a local UPF (user plane function).

20. The EASDF entity of claim 19 , wherein the processor is further configured to:

receive, from the SMF, an update message comprising a changed DNS message processing rule.