Section: 4.3.2.2.4 Multiple PDU Sessions towards the same DNN and S-NSSAI
Content: A UE may establish multiple PDU Sessions associated with the same DNN and S-NSSAI and the AMF may select the same SMF or different SMFs as specified in clause 6.3.2 of TS 23.501[ System architecture for the 5G System (5GS) ]  [2]. During PDU Session establishment, the AMF checks if the SMF selection subscription data indicates that the same SMF is required for multiple PDU Sessions and if required, the AMF checks if any SMF is already selected for the same DNN and S-NSSAI, if so, the same SMF will be used for the additional PDU Session. NOTE 1: The SMF ID can be notified from UDM to the AMF when one AMF is selected for 3GPP access in VPLMN and a different AMF is selected in HPLMN for non-3GPP access. NOTE 2: The same SMF is selected for multiple PDU Sessions towards the same DNN and S-NSSAI to facilitate the selection of the same PCF e.g. for the purpose of usage monitoring.