This counter tracks cells received after the second (higher) observation threshold is exceeded, indicating more severe congestion than the first threshold. Network engineers treat this as a more critical alert than Obs1—crossing the second threshold means congestion is serious and cell loss may be imminent unless traffic is reduced immediately. An Obs2 counter rising while Obs1 is stable indicates the system has progressed from mild to heavy congestion, and manual intervention to shed load may be required within minutes.