Question: In an IP-ATM interworking scenario (Alternative 1) without direct ATM connectivity at the dual-stack RNC/CN-node, what method can be employed to enable ATM connectivity, as per IETF standards?
Option 1: Utilize ATM Emulation over IP protocols via tunnelling techniques.
Option 2: Implement a direct Ethernet handover for ATM data.
Option 3: Employ traditional circuit-switched fallback methods.
Option 4: Upgrade all nodes to support only IP connectivity, bypassing ATM.
Explanation: In scenarios where direct ATM connectivity is not available at the IP&ATM dual-stack RNC/CN-node in Alternative 1 of IP-ATM interworking, using ATM emulation over IP protocols through tunnelling techniques (as specified by IETF standards) provides a viable solution. This approach effectively enables ATM connectivity over IP infrastructure, ensuring compatibility and functionality without requiring direct ATM links.