This read-only value is the incoming-direction counterpart to lportOutAllocbwQoS4, reporting bandwidth currently allocated to active inbound QoS Class 4, best-effort, connections on this port. An admin checks this when trying to understand inbound best-effort load specifically, distinct from outbound, useful when a port is a common destination for bulk incoming best-effort transfers. For example, a port serving as a popular file-server destination would likely show lportInAllocbwQoS4 climbing heavily during large incoming best-effort transfers while the outbound class-4 allocation stays comparatively modest.