Section: 4.12b.4.1 Service Request procedures
Content: The Service Request procedure for devices that do not support 5G NAS signalling over WLAN access shall be used by a TWIF when the CM state in TWIF for a N5CW device is CM-IDLE over Trusted WLAN to request the re-establishment of the NAS signalling connection and the re-establishment of the user plane for all or some of the PDU Sessions which are associated to non-3GPP access. The Service Request procedure for N5CW devices shall be used by a TWIF when the CM state in TWIF for a N5CW device is CM-CONNECTED over trusted WLAN to request the re-establishment of the user plane for one or more PDU Sessions which are associated to non-3GPP access. This Service Request procedure shall be supported as specified in clause 4.12a.4.1 for the trusted non-3GPP access with the following modifications: - The trusted non-3GPP access is substituted by a trusted WLAN access point (TWAP). - The TNGF is substituted by the TWIF. - The TWIF sends and receives NAS messages on behalf of N5CW device. - The user plane between the N5CW device and TWIF is established with Yt' connection instead of IKEv2 signalling.