This application discloses a communication system including a master base station and a secondary base station, both connecting with a terminal. In the communication system, the master base station sends a first message to the secondary base station for allocating transmission resources for one or more flows to be transmitted between the secondary base station and a terminal, wherein the first message carries one or both of: identification information of each flow to be transmitted, and information of a data radio bearer (DRB) associated with each flow to be transmitted, then the secondary base station may determine a mapping relationship between a DRB and an admitted flow according to the first message. Moreover, the master base station sends DRB configuration information to the terminal. Therefore, requirements of 5G communication systems for QoS management of information transmission in a dual connectivity scenario can be met.