This read-only Integer32 (1..65535) uniquely identifies a row in this network port's QoS Shaper statistics table, with index 1 the 15-minute bin, 2 the 1-day bin, and 3 rollover. It lets an administrator select which aggregation window of this network-facing port's shaper activity to retrieve, distinct from the customer-facing traffic port shaper tables. For example, polling index 2 daily on a network uplink port helps track whether core-facing shaping is consistently keeping up with aggregated customer traffic.