A packet forwarding system includes: first relay apparatuses that are connected to each other; a second relay apparatus that includes ports and that is connected to first relay apparatuses; and a control apparatus that configures a trunk serving as virtual logical link by using physical links among first and second relay apparatuses. The control apparatus determines a designated port from ports of first relay apparatuses included in the trunk. When a relay apparatus included in the first relay apparatuses receives a predetermined control target packet, the control apparatus controls the first relay apparatuses to transmit a received control target packet via relay apparatus having the designated port.