The N3IWF for untrusted non-3GPP access, the TNGF for trusted non-3GPP access and the UE may support the IPsec SA rekeying procedure as specified in
RFC 7296. If the N3IWF for untrusted non-3GPP access, the TNGF for trusted non-3GPP access and the UE support the IPsec SA rekying procedure, the UE, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall proactively rekey the IPsec SA. Upon rekeying of an IPsec SA, the UE, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall maintain the old IPsec for the incoming data while establishing the new one. The old IPsec shall be deleted upon the completion of the establishement of the new one by the UE, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access. The UE, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access are separately responsible for enforcing their time expiration policies to rekey the IPsec when needed.
RFC 7296 describes how to avoid the simultaneous IPsec SA and IKE SA rekeying.
The N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall initiate the IPsec SA rekeying procedure by sending a CREATE_CHILD_SA request message with a REKEY_SA Notify payload including a Protocol ID set to "3" and the N3IWF's ESP SPI for untrusted non-3GPP access and the TNGF's ESP SPI for trusted non-3GPP access for the IPsec SA.
Upon reception of the CREATE_CHILD_SA request message with a REKEY_SA Notify payload including a Protocol ID set to
"3" and the N3IWF's ESP SPI for untrusted non-3GPP access or the TNGF's ESP SPI for trusted non-3GPP access for the IPsec SA, if the UE accepts the IPsec SA rekeying request, the UE shall send a CREATE_CHILD_SA response message without an IKEv2 notify payload indicating an error, shall set the UE's ESP SPI to the ESP SPI created by the CREATE_CHILD_SA request/response pair and shall set;
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the N3IWF's ESP SPI for untrusted non-3GPP access; or
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the TNGF's ESP SPI for trsuted non-3GPP access;
to the N3IWF's ESP SPI created by the CREATE_CHILD_SA request/response pair.
If the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access receive a CREATE_CHILD_SA response message with an IKEv2 notify payload indicating an error from the UE, the N3IWF shall delete the IPsec SA as specified in
clause 7.7. Additionally, if the IPsec SA is the signalling IPsec SA, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall delete the IKE SA as specified in
clause 7.4.
If the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access do not receive any CREATE_CHILD_SA response message from the UE, 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. 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.
The UE shall initiate the IPsec SA rekeying procedure by sending a CREATE_CHILD_SA request message with a REKEY_SA Notify payload including a Protocol ID set to "3" and the UE's ESP SPI for the IPsec SA.
Upon reception of the CREATE_CHILD_SA request message with a REKEY_SA Notify payload including a Protocol ID set to
"3" and the UE's ESP SPI for the IPsec SA, if the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access accept the IPsec SA rekeying request, the N3IWF for untrusted non-3GPP access and the TNGF for trusted non-3GPP access shall send a CREATE_CHILD_SA response message without an IKEv2 notify payload indicating an error, shall set:
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the N3IWF's ESP SPI for untrusted non-3GPP access; and
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the TNGF's ESP SPI for trusted non-3GPP access;
to the ESP SPI created by the CREATE_CHILD_SA request/response pair and shall set the UE's ESP SPI to the UE's ESP SPI created by the CREATE_CHILD_SA request/response pair.
If the UE receives a CREATE_CHILD_SA response message with an IKEv2 notify payload indicating an error from the N3IWF for untrusted non-3GPP access or the TNGF for trusted non-3GPP access, the UE shall delete the IPsec SA as specified in
clause 7.7. Additionally, if the IPsec SA is the signalling IPsec SA, the UE shall delete the IKE SA as specified in
clause 7.4.
If the UE does not receive any CREATE_CHILD_SA response message from the N3IWF for untrusted non-3GPP access or the TNGF for trusted non-3GPP access, the UE shall discard all states associated with the IKE SA and any child SAs that were negotiated using that IKE SA. In addition, the UE shall inform the upper layers that the access stratum connection has been released.