This Counter32 object counts the number of collisions a port experienced while transmitting packets. An admin investigating poor performance on a half-duplex or shared-media link watches this counter for a high rate of collisions, since a healthy full-duplex switched link should show essentially none. For example, a port showing a steadily rising collision count would lead the admin to check for a duplex mismatch or a legacy hub attached to that port, since modern full-duplex connections shouldn't generate collisions at all.