Method for managing local nsacf

A primary NSACF (Network Slice Admission Control Function), to perform communication, comprising:

• a transceiver;
• and
• a processor,
• wherein the processor performs operation comprising:
• receiving, from a local NSACF, an update request for a network slice;
• wherein the update request includes ID of a UE (User Equipment), information on the network slice, information on a serving network for the UE and an update flag,
• requesting, to an UDM (Unified Data Management), a result of authentication of the UE for the serving network, based on the update request;
• receiving, from the UDM, a result of authentication of the UE for the serving network;
• determining whether the update request is trustworthy, based on the received result of authentication;
• performing NSAC (Network Slice Admission Control), based on the update request being trustworthy;
• transmitting, to the local NSACF, a response of the update request,
• wherein the response of the update request includes a result of the NSAC, based on the update request being trustworthy.

A method for performing communication, performed by an UDM (Unified Data Management), comprising:

• storing a result of authentication of a UE (User Equipment), based on the authentication of the UE being performed;
• wherein the UE is roaming in a serving network,
• receiving, from a primary NSACF (Network Slice Admission Control Function), a request for the result of authentication of the UE for the serving network;
• wherein the request includes information on the serving network,
• transmitting, to the primary NSACF, the result of authentication, based on the request.