This counts outbound frames on this physical port that were discarded specifically because of severe congestion, as opposed to errors. Because the description ties this explicitly to severe congestion, a nonzero and climbing value here means this port's egress queue is being overwhelmed and traffic shaping or the port's provisioned CIR/PIR should be reviewed for this specific circuit. A PVC-heavy port that starts accumulating pportOutDiscards right after a new high-bandwidth customer is added would suggest that circuit is oversubscribing this port's available egress bandwidth.