5.19.1 General

In order to ensure that the network functions within 5G System are operating under nominal capacity for providing connectivity and necessary services to the UE. Thus, it supports various measures to guard itself under various operating conditions (e.g. peak operating hour, extreme situations). It includes support for load (re-)balancing, overload control and NAS level congestion control. A 5GC NF is considered to be in overload when it is operating over its nominal capacity resulting in diminished performance (including impacts to handling of incoming and outgoing traffic).

AMF and SMFs may, based on operator's policy/configuration and/or upon detection of certain local events, e.g. massive UEs signalling from a UE group, or based on analytics about expected NF load for selected NFs in the network, subscribe at the NWDAF for Signalling Storm Analytics as specified in TS 23.288 [86] to obtain information related to signalling storms caused by excessive UE or NF signalling and may decide to take mitigations actions as described in the present clause 5.19 based on the received analytics information.

In addition, 5GC NFs can consider signalling storm analytics provided by NWDAF as defined in clause 6.22.3 of TS 23.288 [86], to determine the control plane load Control, congestion and overload control, detail example actions of NFs are described in Table 6.22.3-3 in clause 6.22.3 of TS 23.288 [86].