Embodiment 3: the new configuration is completely used for data packet transmission, and all cached data packets are transmitted with the same new configuration, and the information contained in the data packet does not change. This embodiment may include the following steps:
Step 2-3-1: the second node transmits a data configuration message 3 (an optional solution of the third message) to the first node. The function of this message is to configure the transmission of user data. The message includes at least one of the following information:
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        - third configuration information related to the transmitted data packet. For the content contained in the information, please refer to the “configuration information related to the transmitted data packet” in above step 2-1
- third configuration information related to the transmission of the data packet, which does not contain “indication information for indicating to retain the configuration” (for the configuration that needs to be retained indicated by the information, please refer to the “indication information for indicating to retain the configuration” in above step 2-1). In an embodiment, the information contained in the information may be used to configure the transmission of all cached data packets. In another embodiment, the information contained in the information may be used to configure to transmit the data packet indicated by the above “third configuration information related to the transmitted data packet”