A method of conveying data unit traffic from a radio terminal in a mobile communication system that comprises an access network (E-UTRAN) and a core network (Evolved Packet Core) is described. It comprises:—receiving (S31) a service request message for data unit communication from said radio terminal, and—performing (S32) a conveying decision procedure, and on the basis of an outcome of said conveying decision procedure, associating a radio channel between an access network entity and a radio terminal with one of a channel to a dedicated data unit processing entity (P-GW) in said core network for conveying data units from said radio terminal to said dedicated data unit processing entity for processing (S33), and—an access network channel for conveying data units from said radio terminal within said access network (S34).