A communication method executed by a network node in a mobile communication system, and includes the steps of: performing wireless communication with a user equipment in an RRC connected state in a first cell of the network node; and transmitting, to another network node, a request message requesting change of a serving cell of the user equipment from the first cell to a second cell of the other network node. When changing the serving cell through LTM, the network node transmits the request message indicating the change of the serving cell through the LTM. The LTM is a procedure indicating cell switch from the network node to the user equipment through a MAC CE.