This value counts inbound packets the switch has dropped because its ingress packet buffer ran out of space to hold them, indicating the switch received traffic faster than it could process or queue it. An admin monitors this counter to detect ports or the switch overall being oversubscribed, since sustained buffer overflow discards typically mean traffic bursts are exceeding the device's buffering capacity. For example, a steadily increasing value on a heavily loaded uplink port would suggest that port needs more bandwidth or better traffic shaping upstream.