The UE-initiated liveness check procedure enables the UE to detect whether the N3IWF for untrusted non-3GPP access or the TNGF for trusted non-3GPP access is alive.
If the UE supports the TIMEOUT_PERIOD_FOR_LIVENESS_CHECK attribute as specified in
clause 8.2.4.2 of TS 24.302 and the TIMEOUT_PERIOD_FOR_LIVENESS_CHECK attribute as specified in
clause 8.2.4.2 of TS 24.302 was included in the CFG_REPLY configuration payload within the IKE_AUTH response message received in clause 7.3 the UE shall set the timeout period for the liveness check to the value of the TIMEOUT_PERIOD_FOR_LIVENESS_CHECK attribute.
If the UE does not support the TIMEOUT_PERIOD_FOR_LIVENESS_CHECK attribute as specified in
clause 8.2.4.2 of TS 24.302 or the TIMEOUT_PERIOD_FOR_LIVENESS_CHECK attribute as specified in
clause 8.2.4.2 of TS 24.302 was not included in the CFG_REPLY configuration payload within the IKE_AUTH response message received in clause 7.3, then the UE shall use the pre-configured value of the timeout period for liveness check.
If the UE has not received any cryptographically protected IKEv2 or IPsec message for the duration of the timeout period for liveness check, the UE shall send an INFORMATIONAL request with no payloads as per
RFC 7296.
The N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall handle the INFORMATIONAL request with no payloads as per
RFC 7296 and shall send an INFORMATIONAL response.
If an INFORMATIONAL response is received, the UE shall consider the UE-initiated liveness check procedure as successfully completed.
If an INFORMATIONAL response is not received, the UE shall deem the IKEv2 security association to have failed.
The UE shall discard all states associated with the IKE SA and any child SAs that were negotiated using that IKE SA as specified in
RFC 7296]. In addition, the UE shall inform the upper layers that the access stratum connection has been released.