An apparatus includes a first switch circuit in an active mode and a second switch circuit in a standby mode. The apparatus receives high-priority packets and low-priority packets. Each switch circuit stores the high-priority packets and the low-priority packets into first and second buffers, respectively. The each switch circuit performs packet-readout processing reading out a packet from the first and second buffers where the packet-readout processing is performed on the first buffer on a priority basis. The apparatus controls the first switch circuit so that a back-pressure time for the high-priority packets becomes longer with increasing amount of data transmitted by the high-priority packets, when a low-priority packet outputted from the first switch circuit is determined to be a packet that has been received at a first time that is later than a second time at which another low-priority packet outputted from the second switch circuit has been received.