Hello Igor, Naresh is correct the max. link speed for x440-G2 stacking port is 10Gbps. But, the bidirectional stacking link is 40 Gbps, in other words, the stacking bandwidth of x440-G2 is 40Gbps. Note, the port speed is the unidirectional speed of the port. The bidirectional rate = the unidirectional rate X 2 (bidirectional) X 2 (ports).