This read-create Integer32 (1-5651320), measured in cells per second, is the port speed VISM advertises to the controller and uses for SVC/PVC connection admission control and aggregate traffic clipping, and it can only be changed while no resource partition exists on the port. An admin cares because this value gates how much call admission logic believes the port can carry, so misconfiguring it either wastes capacity or risks oversubscription. For example, an operator upgrading a port's underlying link capacity would first remove any existing resource partition so this speed value can be modified to reflect the new bandwidth.