Content for TS 24.502 Word version: 18.0.0
7.9 Network-initiated liveness check procedure
7.9.1 General
7.9.2 Network-initiated liveness check procedure initiation
7.9.3 Network-initiated liveness check procedure completion
7.9.4 Abnormal cases
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7.9 Network-initiated liveness check procedure p. 57
7.9.1 General p. 57
The network-initiated liveness check procedure enables the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access to detect whether the UE is alive.
7.9.2 Network-initiated liveness check procedure initiation p. 57
If the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access has not received any cryptographically protected IKEv2 or IPsec message for the duration of the timeout period for liveness check selected according to the local policy, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall send an INFORMATIONAL request with no payloads RFC 7296.
7.9.3 Network-initiated liveness check procedure completion p. 58
The UE 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 N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall consider the liveness check procedure as successfully completed.
7.9.4 Abnormal cases p. 58
If an INFORMATIONAL response is not received, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall deem the IKEv2 security association to have failed.
The N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access 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 N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall inform the AMF that the access stratum connection has been released.
