Question: What is a key design principle for the Iu interface from a UTRAN perspective, regarding protocol commonality across different Core Network nodes (e.g., 3G-MSC, 3G-SGSN)?
Option 1: Maximizing protocol diversity to allow for node-specific optimizations.
Option 2: Ensuring a common set of radio access bearer services and functional split, independent of Core Network node type.
Option 3: Allowing signaling in the radio network control plane to depend on the specific choice of transport layers.
Option 4: Implementing node-exclusive protocols for each Core Network node type connected to UTRAN.
Explanation: The correct answer, Option 2, reflects the principle of maximizing commonality across different protocols on the Iu interface. This ensures interoperability and simplifies the architecture by providing a uniform set of services and functional splits, regardless of whether the Core Network node is a 3G-MSC or a 3G-SGSN. This approach facilitates more efficient and standardized communication between UTRAN and various Core Network nodes.