Vehicle network system and control method of vehicle network system

A control method of a vehicle network system including a plurality of control devices communicable with each other,

• wherein the plurality of control devices each provided by at least a processor and a memory includes:
• a management-target control device that retains cluster information indicative of a cluster to which the management-target control device belongs among a plurality of clusters being divisions, and that becomes an active state in response to an activation message from another control device including active-cluster information indicative of the cluster to be active that matches the cluster indicated by the cluster information;
• and
• a manager control device that has a function of changing the cluster information of the management-target control device,
• the control method comprising:
• the manager control device transmitting the activation message for activating the management-target control device before transmitting a change message for changing the cluster information of the management-target control device;
• and
• the management-target control device becoming the active state by the activation message transmitted from the manager control device and receiving the change message.