Section: 6.3.8 Handling of serving PLMN rate control
Content: Serving PLMN rate control enables the serving PLMN to protect its MME and the signalling radio bearers in the E-UTRAN from load generated by NAS messages with user data over control plane. The MME can inform the UE of any local serving PLMN rate control during the default EPS bearer context activation procedure (see clause 6.4.1). If the serving PLMN rate control is enabled, the MME shall start the serving PLMN rate control for the PDN connection when the first NAS message with user data over control plane is received over the PDN connection. The UE shall limit the rate at which it generates uplink NAS messages with user data over control plane to comply with the serving PLMN policy provided by the network. The indicated rate in a NAS procedure applies to the PDN connection the NAS procedure corresponds to, and the indicated rate is valid until the PDN connection is released. Serving PLMN rate control is applicable for PDN connections established for control plane CIoT EPS optimization only. Any serving PLMN rate control information provided by the network to the UE is only applicable for the PLMN which provided this information. This serving PLMN rate control information shall be discarded when the UE successfully registers to another PLMN. NOTE: The serving PLMN can discard or delay NAS messages including user data over control plane that exceed the limit provided for serving PLMN rate control.