Question: When is the Ethernet header compression configuration IE included in a message?
Option 1: Only when the UE and network support Control plane CIoT 5GS optimization and Ethernet header compression, and the UE wishes to re-negotiate the configuration.
Option 2: Only after an inter-system change from S1 mode to N1 mode, to negotiate Ethernet header compression configuration associated with a PDU session.
Option 3: When the network initiates the negotiation of Ethernet header compression configuration for a PDU session.
Option 4: Whenever the UE establishes a new PDU session.
Explanation: The Ethernet header compression configuration IE is included in a message when both the UE and network support Control plane CIoT 5GS optimization and Ethernet header compression, and the UE wishes to re-negotiate the configuration associated with a PDU session. This allows for efficient use of resources by compressing Ethernet headers in the 5G system.