Question: In a scenario where control plane and user plane separation of PGW as PGW-C and PGW-U is implemented, how does the PGW-U handle Diameter or RADIUS messages between the DN AAA server in the external PDN and the PGW-C when the AAA server is reachable only via the PGW-U?
Option 1: The PGW-U drops all the Diameter or RADIUS messages.
Option 2: The PGW-U forwards all the Diameter or RADIUS messages to a different node for processing.
Option 3: The PGW-U forwards all the Diameter or RADIUS messages between the DN AAA server in the external PDN and the PGW-C according to the interface specifications.
Option 4: The PGW-U modifies the Diameter or RADIUS messages before forwarding them.
Explanation: According to the control plane and user plane separation of PGW, when the AAA server is reachable only via the PGW-U, the PGW-U acts as a forwarder for all the Diameter or RADIUS messages between the DN AAA server in the external PDN and the PGW-C. This ensures that communication between the nodes is maintained while adhering to the separation architecture.