MeNB站间携带SN的X2切换流程过程，源MN发送哪条消息给目标MN？该消息中携带MCG和SCG相关配置信息，NR测量结果。目标MN根据测量结果触发目标SN添加过程，发送sgNB Addition Request给目标SN
AHandover Request
BSENB Modi fi cation Request
CRrc Connection Reconfi gurati on
DHandover Request Acknowledge message