An array of columns and rows of host server devices is mounted in a row of racks. Each device has a host processor and an exact-match packet switching integrated circuit. Packets are switched within the system using exact-match flow tables that are provisioned by a central controller. Each device is coupled by a first cable to a device to its left, by a second cable to a device to its right, by a third cable to a device above, and by a fourth cable to a device below. In one example, substantially all cables that are one meter or less in length are non-optical cables, whereas substantially all cables that are seven meters or more in length are optical cables. Advantageously, each device of a majority of the devices has four and only four cable ports, and connects only to non-optical cables, and the connections involve no optical transceiver.