Question: In a VPLMN with PMIPv6 on S2b interface, where is Lawful Interception performed for I-WLAN, and what triggers an event at the PDN-GW?
Option 1: LI is performed at the S-GW; a UE's Initial Attach triggers a PMIP attach event at the PDN-GW.
Option 2: LI is not applicable for I-WLAN in this scenario; only a PDN connection activation triggers an event.
Option 3: LI is done at the ePDG according to I-WLAN requirements; a detected attach or PDN connectivity activation over PMIP triggers a PMIP attach/tunnel activation event at the PDN-GW.
Option 4: LI is performed at both ePDG and S-GW; either Initial Attach or PDN connection activation can trigger an event.
Explanation: This option correctly identifies that in a VPLMN with PMIPv6 on S2b, Lawful Interception for I-WLAN is specifically performed at the ePDG, adhering to I-WLAN requirements. The detection of either an Initial Attach or a PDN connectivity activation over PMIPv6 triggers a PMIP attach/tunnel activation event at the PDN-GW, highlighting the integration of WLAN interworking with cellular networks and the importance of lawful interception in such architectures.