A blade server is capable of being mounted with a plurality of operation blades, a plurality of switch blades, and I/O blades. The operation blades have CPUs that emit packets for the I/O blades. The switch blades include a crossbar that selects two or more of the plurality of operation blades, comparators that compare two or more packets emitted by CPUs that the two or more operation blades selected by the crossbar are provided with, and a further crossbar that transfers the compared packets to the I/O blades based on comparison results of the comparators.