Section: Modify Bearer Request
Content: The direction of this message shall be from MME/S4-SGSN to SGW and/or from SGW to PGW (see Table 6.1-1). The Modify Bearer Request message shall only be sent on the S11 interface by the MME to the SGW and on the S5/S8 interfaces by the SGW to the PGW as part of the procedures: - E-UTRAN Tracking Area Update without SGW Change - UE triggered Service Request - S1-based Handover - UTRAN Iu mode to E-UTRAN Inter RAT handover - GERAN A/Gb mode to E-UTRAN Inter RAT handover - Tracking Area Update procedure with a RAT type change - E-UTRAN Initial Attach - Handover from Trusted or Untrusted Non-3GPP IP Access to E-UTRAN with GTP on S5/S8 interface (see clauses 8.2, 8.6 and 16.11 of 3GPP TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [45]) - UE requested PDN connectivity - SGSN to MME combined hard handover and SRNS relocation procedure - X2-based handover without SGW relocation - UTRAN/GERAN to E-UTRAN SRVCC - HSS-based P-CSCF restoration for 3GPP access (see 3GPP TS 23.380[ IMS Restoration Procedures ]  [61]) - Connection Resume procedure (see clause 5.3.5A of 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [3]) - reception of the RRC establishment cause "MO Exception data" in the NB-IoT RAT It shall also only be sent on the S11 interface by the MME to the SGW as part of the procedure: - E-UTRAN Initiated E-RAB modification procedure - Handover from Trusted or Untrusted Non-3GPP IP Access to E-UTRAN with PMIP on S5/S8 interface (see clauses 8.2 and 16.11 of 3GPP TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [45]) - Tracking Area Update procedure with Serving GW change and data forwarding - Mobile Originated Data transport in Control Plane CIoT EPS optimisation with P-GW connectivity - Mobile Terminated Data Transport in Control Plane CIoT EPS optimisation with P-GW connectivity - Establishment of S1-U bearer during Data Transport in Control Plane CIoT EPS optimisation procedure (see clause 5.3.4B.4 of 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [3]). It shall also only be sent on the S4 interface by the SGSN to the SGW and on the S5/S8 interfaces by the SGW to the PGW as part of the procedures: - Routeing Area Update with MME interaction and without SGW change - E-UTRAN to UTRAN Iu mode Inter RAT handover - E-UTRAN to GERAN A/Gb mode Inter RAT handover - Inter SGSN Routeing Area Update Procedure and Combined Inter SGSN RA / LA Update to S4 SGSNs without SGW change - Iu mode RA Update Procedure without SGW change - Serving RNS Relocation Procedure - Combined Hard Handover and SRNS Relocation Procedure - Combined Cell / URA Update and SRNS Relocation Procedure - Enhanced Serving RNS Relocation without SGW relocation - UE Initiated Service Request Procedure - Iu mode to A/Gb mode Intra SGSN Change - A/Gb mode to Iu mode Intra SGSN Change - Iu mode to A/Gb mode Inter-SGSN Change - A/Gb mode to Iu mode Inter-SGSN Change - Paging Response with no established user plane on S4 - PDP Context Activation Procedure - Handover from Trusted or Untrusted Non-3GPP IP Access to UTRAN/GERAN with GTP on S5/S8 interface (see clauses 8.2, 8.6 and 16.11 of 3GPP TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [45]) - UTRAN/GERAN to UTRAN (HSPA) SRVCC - HSS-based P-CSCF restoration for 3GPP access (see 3GPP TS 23.380[ IMS Restoration Procedures ]  [61]) It shall also only be sent on the S4 interface by the SGSN to the SGW as part of the procedures: - RAB Assignment Procedure - SRVCC from E-UTRAN to UTRAN or GERAN with DTM HO support procedures and SRVCC from UTRAN (HSPA) to UTRAN or GERAN with DTM HO support. - Handover from Trusted or Untrusted Non-3GPP IP Access to UTRAN/GERAN with PMIP on S5/S8 interface (see clauses 8.2 and 16.11 of 3GPP TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [45]) - Routeing Area Update procedure with Serving GW change and data forwarding and only on the S5/S8 interfaces by the SGW to the PGW as part of the procedures: - Tracking Area Update procedure with SGW change - Gn/Gp SGSN to S4 SGSN Routing Area Update - X2 based handover with SGW relocation - Gn/Gp SGSN to MME Tracking Area Update - Enhanced Serving RNS Relocation with SGW relocation - Routeing Area Update with MME interaction and with SGW change - Inter SGSN Routeing Area Update Procedure and Combined Inter SGSN RA / LA Update using S4 with SGW change - Iu mode RA Update Procedure using S4 with SGW change - Restoration of PDN connections after an SGW failure if the MME/SGSN and PGW support these procedures as specified in 3GPP TS 23.007[ Restoration procedures ]  [17] - MME triggered Serving GW relocation - S4-SGSN triggered Serving GW relocation - PGW Pause of Charging procedure and on the S2b interface by the ePDG to the PGW as part of the procedures: - UE initiated IPsec tunnel update procedure If the optional network triggered service restoration feature is supported by the MME, SGSN and SGW, then the Modify Bearer Request message shall also be sent as part of the network triggered service restoration procedure with ISR during an intra MME TAU and an intra S4-SGSN RAU procedure for UEs that had ISR active before either the MME or the S4-SGSN has restarted, as specified in 3GPP TS 23.007[ Restoration procedures ]  [17]: - on the S11 interface by the MME to the SGW, if the MME detected that the ISR associated S4-SGSN has restarted and UE performs a TAU procedure; - on the S4 interface by the S4-SGSN to the SGW, if the S4-SGSN detected that the ISR associated MME has restarted and UE performs a RAU procedure. This message can be used as an implicit resume of the suspended bearers in the SGW and in the PGW (see 3GPP TS 23.216[ Single Radio Voice Call Continuity (SRVCC); Stage 2 ]  [43] clauses 6.2.2.1 and 6.3.2.1, 3GPP TS 23.272[ Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2 ]  [21] clauses 6.3, 6.5 and 7.4). A Modify Bearer Request used as an implicit resume can contain zero or more IE(s), depending on the conditions of presence of the IEs specified in table 7.2.7-1. The PGW should not consider a Modify Bearer Request with zero IE as an error. The Modify Bearer Request message may also be sent in the following cases from the S4-SGSN to the SGW/PGW to report a change of Serving Network, User CSG Information or/and UE Time Zone which occured during a previous RAU procedure without SGSN change but which has not been reported yet to the SGW/PGW, or to indicate to the PGW that the UE is available for signalling if the PDN connection is delay tolerant and if there is pending network initiated PDN connection signalling: - during a Service Request procedure to establish data radio bearers for the corresponding PDP context for a UE in UTRAN with an existing S4-U tunnel; - when the SGSN receives an uplink LLC PDU for user data or any valid LLC frame serving as a paging response from a UE in GERAN with an existing S4-U tunnel. The Modify Bearer Request message may also be sent in the following cases from the S4-SGSN to the SGW/PGW to report a change of User Location Information which occured during a previous RAU procedure without SGSN change but which has not been reported yet to the SGW/PGW, if the S4-SGSN is configured to defer the reporting of ULI change until a RAB/user plane is established: - during a Service Request procedure to establish data radio bearers for the corresponding PDP context for a UE in UTRAN with an existing S4-U tunnel; - when the SGSN receives an uplink LLC PDU for user data or any valid LLC frame serving as a paging response for a UE in GERAN with an existing S4-U tunnel. NOTE 1: the S4-SGSN can alternatively send a Change Notification Request message in the above cases, if no other information which requires the sending of a Modify Bearer Request, needs to be reported to the PGW. The Modify Bearer Request message may also be sent by the MME to the SGW/PGW to report a change of Serving Network, User Location Information, User CSG Information, UE Time Zone or/and RAT Type, when user data is transported in NAS signalling, for a UE with an existing S11-U tunnel. When requesting the PGW to pause or unpause charging for a PDN connection, the SGW shall wait for the PGW acknowledgement (i.e. Modify Bearer Response) before sending a new pause or unpause request. NOTE 2: this ensures that the PGW always act per the most recent SGW request in particular in scenarios where the SGW would need to request the PGW to pause and unpause charging in a row (or vice-versa) and the Modify Bearer Request messages would arrive out of order at the PGW. Upon receipt of a request from the PGW/PCRF/OCS in a message other than Create Bearer Request and Update Bearer Request to report changes of UE presence in new or modified Presence Reporting Area(s), the MME/S4-SGSN shall immediately send a Modify Bearer Request message or a Change Notification Request message to report to the PGW whether the UE is inside or outside the new or modified Presence Reporting Area(s) or whether the Presence Reporting Area(s) is inactive. The MME/S4-SGSN shall also send a Modify Bearer Request message or a Change Notification Request message to report any subsequent change of UE presence in the Presence Reporting Area, as specified in 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [3] and 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [35]. If the Modify Bearer Request message is sent from the old MME/SGSN as part of Tracking/Routeing Area Update procedure with SGW change and data forwarding as specified in clause 5.3.3.1A of 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [3], the old MME/SGSN shall only include the Bearer Contexts to be modified IE. NOTE 3: Since the UE has left the old MME/SGSN, some information related to the UE, e.g. ULI, UE Time Zone, CSG, RAT Type in the old MME/SGSN are not valid any more. Upon receipt of a Modify Bearer Request message that includes the Presence Reporting Area Information from the MME/S4-SGSN, the SGW shall send a Modify Bearer Request message on the S5/S8 interface if any of the following condition is met: - ISR is not active; - ISR is active, and the RAT Type has changed since last reported or the CPRAI flag has been set to 1. The MME shall increment the "MO Exception data counter" by one each time the MME has received the RRC cause "MO Exception data". The MME may defer sending a Modify Bearer Request message to report a non-zero value for the MO Exception Data Counter based on local configuration. Upon receipt of a Modify Bearer Request message that includes the Secondary RAT Usage Data Report from the MME, the SGW shall send a Modify Bearer Request message on the S5/S8 interface if the IRPGW flag is set to 1 in the Secondary RAT Usage Data Report IE. Table -1: Information Elements in a Modify Bearer Request Table -2: Bearer Context to be modified within Modify Bearer Request Table -3: Bearer Context to be removed within Modify Bearer Request Table 7.2.7-4: Overload Control Information within Modify Bearer Request