Question: What constitutes a valid associated tunnel address pair for an E-RAB ID in the context of S1AP, to avoid being considered a logical error by the eNB?
Option 1: Presence of only GTP-TEID IE for both UL and DL directions.
Option 2: Presence of both GTP-TEID IE and Transport Layer Address IE for either UL or DL (or both).
Option 3: Presence of Transport Layer Address IE alone, without GTP-TEID IE, for both UL and DL.
Option 4: Absence of both GTP-TEID IE and Transport Layer Address IE for non-active bearers.
Explanation: A valid tunnel address pair requires the presence of two crucial elements to ensure proper routing and identification: the GTP Tunnel Endpoint Identifier (GTP-TEID) for identifying the tunnel, and the Transport Layer Address for specifying where to send the packets. Having both ensures that data can be correctly forwarded in either the uplink (UL), downlink (DL), or both directions, thus avoiding logical errors as per S1AP protocol specifications.