This is a running count of every ATM cell transmitted on this logical port, the outbound counterpart to lportInCells, letting the admin verify egress traffic volume and compute an actual transmit cell rate. Comparing lportInCells to lportOutCells over time can reveal whether the port's inbound and outbound load are balanced or heavily asymmetric. For example, a port showing steadily rising InCells but flat OutCells suggests inbound traffic is arriving but not being forwarded, pointing to downstream congestion or a routing problem.