A distributing control unit performs provisional switching control processing to a distributing unit when a link in use for first data units is a first link and a candidate link to be used is a second link. For example, the distributing control unit distributes at least one of the data units of the first data units of the data stream to the second link and distributes other data units to the first link. A determining unit determines whether or not a link in use for second data units subsequent to the first data units is to be switched from the first link to the second link based on first and second communication qualities, the first and second communication qualities being based on feedback information. The first and second communication qualities are communication qualities of the other data units and the at least one of the data units, respectively.