A method for controlling a session in a target Mobility Management Entity, MME, taking charge of a control plane within a mobile communication network, the method comprising: receiving, by the target MME, a tracking area update, TAU, request message of a terminal via a target base station; obtaining, by the target MME, information indicating that the session of the terminal is established to be passed through a path over nodes within a fixed network different from the mobile communication network, - wherein the information includes a parameter that is related to Selected Internet Protocol Traffic Offload, SIPTO, and indicates whether the session is a SIPTO-based session, and - wherein the information is either set together with an access point name, APN, or set in a unit of bearer, within a UE context; deciding, by the target MME, whether gateway relocation is needed depending on whether the session is a SIPTO-based session, and if there is a SIPTO-based session, determining, by the target MME, a target serving gateway, S-GW, or target packet data network gateway, P-GW, to be in charge for the terminal; releasing, by the target MME, the established session for the terminal; transmitting, by the target MME, an accept message to the terminal via the target base station, the accept message comprising information for a processing result for the SIPTO-based session; and establishing, by the target MME, a new session passing through a path over the nodes within the fixed network based on the parameter included in the information, wherein releasing the previously established session comprises: - releasing at least one session associated with the APN among sessions in which the terminal is performing, if the information is set together with the APN, by: -- sending, from the target MME to a source serving gateway, SGW, (521, 401), a Delete Session Request message to delete the SIPTO-based session, if it is determined to select a new GW. receiving, by the target MME, a tracking area update, TAU, request message of a terminal via a target base station; obtaining, by the target MME, information indicating that the session of the terminal is established to be passed through a path over nodes within a fixed network different from the mobile communication network, - wherein the information includes a parameter that is related to Selected Internet Protocol Traffic Offload, SIPTO, and indicates whether the session is a SIPTO-based session, and - wherein the information is either set together with an access point name, APN, or set in a unit of bearer, within a UE context; - wherein the information includes a parameter that is related to Selected Internet Protocol Traffic Offload, SIPTO, and indicates whether the session is a SIPTO-based session, and - wherein the information is either set together with an access point name, APN, or set in a unit of bearer, within a UE context; deciding, by the target MME, whether gateway relocation is needed depending on whether the session is a SIPTO-based session, and if there is a SIPTO-based session, determining, by the target MME, a target serving gateway, S-GW, or target packet data network gateway, P-GW, to be in charge for the terminal; releasing, by the target MME, the established session for the terminal; transmitting, by the target MME, an accept message to the terminal via the target base station, the accept message comprising information for a processing result for the SIPTO-based session; and establishing, by the target MME, a new session passing through a path over the nodes within the fixed network based on the parameter included in the information, wherein releasing the previously established session comprises: - releasing at least one session associated with the APN among sessions in which the terminal is performing, if the information is set together with the APN, by: -- sending, from the target MME to a source serving gateway, SGW, (521, 401), a Delete Session Request message to delete the SIPTO-based session, if it is determined to select a new GW. - releasing at least one session associated with the APN among sessions in which the terminal is performing, if the information is set together with the APN, by: -- sending, from the target MME to a source serving gateway, SGW, (521, 401), a Delete Session Request message to delete the SIPTO-based session, if it is determined to select a new GW.