The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). The embodiments in the present disclosure allow to transfer remaining data between different base stations in a dual-registration interworking process, which provides terminal mobility between 4G and 5G networks without a data loss. Further, it provides the terminal mobility with no data loss without changing 5G and 4G base station implementation through addition of a simple function of new equipment, such as SMF and UPF. Further, it supports different QoS and forwarding path units in the 5G/4G networks without changing 5G and 4G base station functions. Further, it exempts additional function implementation costs for re-ordering in a terminal and a network through in-order delivery of packets to the terminal without changing the packet order during 4G-5G network movement.
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