A master radio access network, RAN, node associated with a master radio access technology, RAT, the master RAN node comprising: a memory ; and at least one processor coupled to the memory and configured to: communicate with a secondary RAN node associated with a secondary RAT and provide a radio terminal with dual connectivity that uses the master RAT and the secondary RAT, the master RAT and the secondary RAT being different RAT from each other; and in response to receiving , from the radio terminal or a core network , terminal capability information indicating that the radio terminal supports a split bearer, use a Packet Data Convergence Protocol, PDCP, entity for a master cell group split bearer for the radio terminal , the PDCP entity providing unified PDCP functionalities, wherein the unified PDCP functionalities are also used for a PDCP entity in the secondary RAN node for a secondary cell group split bearer, the master cell group split bearer is a user plane bearer whose radio protocols are split at the master RAN node and belong to both a master cell group provided by the master RAN node and a secondary cell group provided by the secondary RAN node , and the secondary cell group split bearer is a user plane bearer whose radio protocols are split at the secondary RAN node and belong to both the secondary cell group and the master cell group. a memory ; and at least one processor coupled to the memory and configured to: communicate with a secondary RAN node associated with a secondary RAT and provide a radio terminal with dual connectivity that uses the master RAT and the secondary RAT, the master RAT and the secondary RAT being different RAT from each other; and in response to receiving , from the radio terminal or a core network , terminal capability information indicating that the radio terminal supports a split bearer, use a Packet Data Convergence Protocol, PDCP, entity for a master cell group split bearer for the radio terminal , the PDCP entity providing unified PDCP functionalities, wherein communicate with a secondary RAN node associated with a secondary RAT and provide a radio terminal with dual connectivity that uses the master RAT and the secondary RAT, the master RAT and the secondary RAT being different RAT from each other; and in response to receiving , from the radio terminal or a core network , terminal capability information indicating that the radio terminal supports a split bearer, use a Packet Data Convergence Protocol, PDCP, entity for a master cell group split bearer for the radio terminal , the PDCP entity providing unified PDCP functionalities, wherein the unified PDCP functionalities are also used for a PDCP entity in the secondary RAN node for a secondary cell group split bearer, the master cell group split bearer is a user plane bearer whose radio protocols are split at the master RAN node and belong to both a master cell group provided by the master RAN node and a secondary cell group provided by the secondary RAN node , and the secondary cell group split bearer is a user plane bearer whose radio protocols are split at the secondary RAN node and belong to both the secondary cell group and the master cell group. <EOS>