A variety of access technologies have been deployed over the last few years, and mobile nodes now have multiple network interfaces. In addition, mobile communications has been an active research area for several years. We have developed a link aggregation system with Mobile IP. This link aggregation system, called SHAKE, is intended to improve the throughput and reliability of wireless communication by making it possible to use multiple Internet-linked mobile nodes simultaneously and disperse the traffic between mobile nodes and a correspondent node. This paper describes a collaboration mechanism that provides packet-based and flow-based traffic distributive control based on user preferences and the cooperating nodes' states. Evaluations of a prototype implementation show that the mechanism is advantageous for a cooperative communication system like SHAKE. The results of experiments reveal that the flow-based traffic distribution is effective when the delay jitters of the nodes are extremely different.