Question: In E-UTRAN, when an eNB (eNodeB) knows the eNB ID but not the TNL (Transport Network Layer) address of a candidate eNB for SCTP (Stream Control Transmission Protocol) connectivity, what is the primary function utilized by the eNB to discover the TNL address via the S1 interface?
Option 1: Automatic Neighbor Relation (ANR) Function
Option 2: Configuration Transfer Function
Option 3: Mobility Management Entity (MME) Bypass Procedure
Option 4: Direct X2 Interface Query
Explanation: The correct answer is the Configuration Transfer Function. This function is used when an eNB needs to obtain the TNL address of another eNB for establishing SCTP connectivity, but only knows the target eNB's ID. The process involves the initiating eNB requesting the MME, which then relays the request to the candidate eNB, and finally, the response with the TNL address is relayed back through the MME.