Section: 5.25.1 Support of Tracing: Signalling Based Activation/Deactivation of Tracing
Content: 5GS supports tracing as described in TS 32.421[ Telecommunication management; Subscriber and equipment trace; Trace concepts and requirements ]  [66]. 5GS support may include subscriber tracing (tracing targeting a SUPI) or equipment tracing (tracing targeting a PEI) but also other forms of tracing further described in TS 32.421[ Telecommunication management; Subscriber and equipment trace; Trace concepts and requirements ]  [66]. NOTE 1: TS 23.501[ System architecture for the 5G System (5GS) ]  / TS 23.502[ Procedures for the 5G System (5GS) ]  [3] / TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [45] only describe how 5GS signalling supports delivery of Trace Requirements about a UE (Signalling Based Activation/Deactivation of Tracing). OAM delivery of tracing requirements as well as the transfer of tracing results to one or more Operations Systems are out of scope of these documents. The content of Trace Requirements about a UE (e.g. trace reference, address of the Trace Collection Entity, etc.) is defined in TS 32.421[ Telecommunication management; Subscriber and equipment trace; Trace concepts and requirements ]  [66]. Trace Requirements about a UE may be configured in subscription data of the UE and delivered together with other subscription data by the UDM towards the AMF, the SMF and/or the SMSF. The AMF propagates Trace Requirements about a UE received from the UDM to network entities not retrieving subscription information from UDM, i.e. to the 5G-AN, to the AUSF and to the PCF. The AMF also propagates Trace Requirements to the SMF and to the SMSF. If the I-SMF or V-SMF is needed for the PDU session, the AMF propagates Trace Requirements to the I-SMF or V-SMF. The I-SMF or V-SMF also propagates Trace Requirements received from the AMF to the I-UPF or V-UPF (over N4). Trace Requirements about a UE may be sent by the AMF to the 5G-AN as part of: - the N2 procedures used to move the UE from CM-IDLE to CM-CONNECTED or, - the N2 procedures to request a Hand-over from a target NG-RAN or, - a stand-alone dedicated N2 procedure when tracing is activated while the UE is CM-CONNECTED. Trace Requirements about a UE sent to a 5G-AN shall not contain information on the SUPI or on the PEI of the UE. Trace Requirements are directly sent from Source to Target NG-RAN in the case of Xn Hand-Over. The SMF propagates Trace Requirements about a UE received from the UDM to the UPF (over N4) and to the PCF. The SMF provides Trace Requirements to the PCF when it has selected a different PCF than the one received from the AMF. Once the SMF or the SMSF has received subscription data, Trace Requirements received from UDM supersede Trace requirements received from the AMF. Trace Requirements are exchanged on N26 between the AMF and the MME.