Exactly as described, this counts packets dropped on this benchmark port specifically when traffic profiles are enabled, and is only applicable on 311v-variant hardware. Because this only applies under the 311v traffic-profile feature, seeing this counter present but permanently at zero on non-311v hardware or with traffic profiles disabled is expected and not a sign of anything wrong -- it's a scoped, conditional counter rather than a general drop indicator. For example, on a 311v platform running an active traffic profile, this counter incrementing alongside a throughput test would indicate the traffic-profile shaping itself, not the network path, is discarding excess frames.