Section: .1 Downlink Data Notification
Content: A Downlink Data Notification message shall be sent: - on the S11 interface by the SGW to the MME as a part of the network triggered service request procedure; - on the S4 interface by the SGW to the S4-SGSN as part of Paging with no established user plane on S4, SGW triggered paging with S4; - on the S4 interface by the SGW to the S4-SGSN to re-establish all the previous released bearer(s) for a UE, upon receipt of downlink data for a UE in connected mode but without corresponding downlink bearer available; NOTE: This may occur e.g. if the S4-SGSN releases some but not all the bearers of the UE as specified in clause 12.7.2.2 of 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [35]. - on S11/S4 interface by SGW to MME/S4-SGSN if the SGW has received an Error Indication (see 3GPP TS 29.281[ General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U) ]  [13]) from eNodeB/RNC/MME across S1-U/S12/S11-U interface. Respective SGW and MME/S4-SGSN functionality is specified in 3GPP TS 23.007[ Restoration procedures ]  [17]. - on the S11/S4 interface by SGW to the MME/S4-SGSN as part of the network triggered service restoration procedure if both the SGW and the MME/S4-SGSN support this optional feature (see 3GPP TS 23.007[ Restoration procedures ]  [17]). - on the S11 interface by the SGW to the MME as a part of the Mobile Terminated Data Transport in Control Plane CIoT EPS optimisation with P-GW connectivity. A Downlink Data Notification message may be sent: - on the S4 by the SGW to the S4-SGSN if the SGW has received an Error Indication from S4-SGSN across S4-U interface. Table .1-1 specifies the presence of the IEs in the message. Table .1-1: Information Elements in a Downlink Data Notification Table 7.2.11.1-2: Load Control Information within Downlink Data Notification Table 7.2.11.1-3: Overload Control Information within Downlink Data Notification