Bounding cell reorder depth is disclosed. It is determined whether a reorder buffer that is associated with a switch fabric exceeds a depth limit. In the event that the reorder buffer exceeds the depth limit, backpressure with respect to a source associated with the reorder buffer is sent. In such cases source based back pressure information is included in a reserved field in a cell that is being sent into the switch fabric. In the event that the reorder buffer does not exceed the depth limit, the cell is sent to the switch fabric. In such cases the reserved field is present in the cell but is unused.