Question: In a UMTS network, what is the primary purpose of measuring 'Ingress cells (whole stream)' on an ATM node?
Option 1: To monitor the overall network latency for packet-switched traffic.
Option 2: To track the number of failed circuit-switched connections.
Option 3: To provide the total count of incoming cells across all traffic types (circuit-switched and packet-switched) on the IubLink.
Option 4: To gauge the bandwidth utilization for dedicated channels.
Explanation: Measuring 'Ingress cells (whole stream)' is crucial for understanding the total volume of incoming traffic (both circuit-switched and packet-switched) at the ATM node level, specifically on the IubLink. This metric helps in network planning, capacity management, and ensuring the overall efficiency of the UMTS network's terrestrial radio access part. It directly relates to the monitoring of all incoming cell traffic.