- diff_pkts_rx = stats.ipackets - prev_pkts_rx[port_id];
- diff_pkts_tx = stats.opackets - prev_pkts_tx[port_id];
+ diff_pkts_rx = (stats.ipackets > prev_pkts_rx[port_id]) ?
+ (stats.ipackets - prev_pkts_rx[port_id]) : 0;
+ diff_pkts_tx = (stats.opackets > prev_pkts_tx[port_id]) ?
+ (stats.opackets - prev_pkts_tx[port_id]) : 0;