This read-only counter, in cells, tracks the number of valid ATM cells with the EFCI header bit set to 1 in the ingress direction of this channel, measured before the class-of-service queue, indicating cells that experienced forward congestion upstream. An admin monitors this to detect when upstream network segments are experiencing congestion that is being signaled forward to this switch via the EFCI mechanism, even before any local queue buildup. For example, if this counter rises sharply while the switch's own queues are otherwise healthy, the admin would suspect the congestion is occurring further upstream in the network rather than locally.