The disclosure relates to a plurality of network routers for performing collective operations and an accelerator
system including the network routers. A
network router includes: a
receiver configured to receive a first input packet from a first other
network router in a first direction, receive a second input packet from a second other
network router in a second direction, and output one of the first input packet or the second input packet as a collective packet; a network controller configured to receive the collective packet from the
receiver and output the collective packet through a first path or a second path based on a packet type of the collective packet; a buffer circuit configured to store, in a distinguishable manner, the collective packet transferred from the network controller through the second path based on a packet type of the collective packet; and a reduction operation circuit configured to receive the collective data packet stored in the buffer circuit, and perform a reduction operation using the received collective data packet.