Question: In a 3GPP EPS scenario, when a Diameter Re-Auth-Request (RAR) command is sent from a 3GPP AAA server to an untrusted non-3GPP access network NAS for SWa HSS/AAA Initiated Detach, what is the significance of the 'R' bit set in the Command Flags field?
Option 1: Indicates the request is part of a roaming scenario.
Option 2: Signifies that the command is a re-authentication request, prompting the NAS to initiate a re-authentication process with the UE (User Equipment).
Option 3: Specifies that the response should be sent to a proxy server.
Option 4: Denotes that the request is related to a QoS (Quality of Service) update.
Explanation: The 'R' bit set in the Command Flags field of the Diameter Re-Auth-Request (RAR) command indicates to the untrusted non-3GPP access network NAS that this command is specifically for re-authentication purposes, prompting the NAS to initiate a re-authentication process with the UE, ensuring the validity and security of the ongoing session in the context of SWa HSS/AAA Initiated Detach procedures.