The present disclosure relates to a technology for providing a service of effectively transmitting and receiving data by simultaneously using a 3GPP system and a non-3GPP system in a network in which the 3GPP system and the non-3GPP system coexist. A communication method of a non-3GPP access network entity according to embodiments of the present disclosure includes receiving overload status information from a gateway; receiving a session management request message from a user equipment (UE); and transmitting a session management reject message comprising a back-off timer to the UE. According to the embodiment of the present disclosure, when a specific PDN (or APN) is overloaded, the overload state can be controlled.