7.2.11 Downlink Data Notification messages

29.2743GPP3GPP Evolved Packet System (EPS)Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C)Release 16Stage 3TS

7.2.11.1 Downlink Data Notification

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 [35].

– on S11/S4 interface by SGW to MME/S4-SGSN if the SGW has received an Error Indication (see 3GPP TS 29.281 [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 [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 [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 7.2.11.1-1 specifies the presence of the IEs in the message.

Table 7.2.11.1-1: Information Elements in a Downlink Data Notification

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

CO

If SGW receives an Error Indication from eNodeB/RNC/S4-SGSN/MME, the SGW shall send the Cause IE with value "Error Indication received from RNC/eNodeB/S4-SGSN/MME" to MME/S4-SGSN as specified in 3GPP TS 23.007 [17].

Cause

0

EPS Bearer ID

CO

This IE shall be included on the S11 and S4 interfaces and shall be set as follows:

  • If the Downlink Data Notification is triggered by the arrival of downlink data packets at the SGW, the SGW shall include the EPS Bearer ID stored in the EPS bearer context of the bearer on which the downlink data packet was received;
  • If the Downlink Data Notification is triggered by the receipt of an Error Indication from the eNodeB, RNC or S4-SGSN, the SGW shall include the EPS Bearer ID stored in the EPS bearer context of the bearer for which the Error Indication was received;
  • If the ISR is active and the Downlink Data Notification is triggered by the arrival of control plane signalling, the SGW shall include the EPS Bearer ID present in the control plane signalling or derived from the control plane signaling (for PMIP based S5/S8), See NOTE 3). For a Downlink Data Notification triggered by a Create Bearer Request message, the SGW shall include the EPS Bearer ID of the corresponding PDN connection’s default bearer.
  • If both the SGW and the MME/S4-SGSN support the network triggered service restoration procedure (see 3GPP TS 23.007 [17]), and if the Downlink Data Notification is triggered by the arrival of control plane signalling, the SGW shall include the EPS Bearer ID present in the control plane signalling or derived from the control plane signaling (for PMIP based S5/S8). (See 3GPP TS 23.401[3], clause 5.3.4.3).

More than one IE with this type and instance values may be included to represent multiple bearers having received downlink data packets or being signalled in the received control plane message.

See NOTE 1.

EBI

0

Allocation/Retention Priority

CO

This IE shall be included on the S11 and S4 interfaces and shall be set as follows:

  • If the Downlink Data Notification is triggered by the arrival of downlink data packets at the SGW, the SGW shall include the ARP stored in the EPS bearer context of the bearer on which the downlink data packet was received;
  • If the Downlink Data Notification is triggered by the receipt of an Error Indication from the eNodeB, RNC or S4-SGSN, the SGW shall include the ARP stored in the EPS bearer context of the bearer for which the Error Indication was received.
  • If the ISR is active and the Downlink Data Notification is triggered by the arrival of control plane signalling, the SGW shall include the ARP if present in the control plane signalling. If the ARP is not present in the control plane signalling, the SGW shall include the ARP in the stored EPS bearer context. See NOTE 3.
  • If both the SGW and the MME/S4-SGSN support the network triggered service restoration procedure (see 3GPP TS 23.007 [17]), and if the Downlink Data Notification is triggered by the arrival of control plane signalling, the SGW shall include the ARP if present in the control plane signalling. If the ARP is not present in the control plane signalling, the SGW shall include the ARP from the stored EPS bearer context.

(See 3GPP TS 23.401[3], clause 5.3.4.3).

If multiple EPS Bearers IDs are reported in the message, the SGW shall include the ARP associated with the bearer with the highest priority (i.e. the lowest ARP Priority Level value).

See NOTE 1.

ARP

0

IMSI

CO

This IE shall be included on the S11/S4 interface 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 [17]).

IMSI

0

Sender F-TEID for Control Plane

O

This IE may be included on the S11/S4 interface towards the restarted CN node or an alternative CN node (same type of mobility node as the failed one) as part of the network triggered service restoration procedure with or without ISR if both the SGW and the MME/S4-SGSN support this optional feature (see 3GPP TS 23.007 [17]).

This IE shall not be included otherwise.

(NOTE 2)

F-TEID

0

Indication Flags

CO

This IE shall be included if any one of the applicable flags is set to 1.

Applicable flags are:

  • Associate OCI with SGW node’s identity: The SGW shall set this flag to 1 on the S11/S4 interface if it has included the "SGW’s Overload Control Information" and if this information is to be associated with the node identity (i.e. FQDN or the IP address received from the DNS during the SGW selection) of the serving SGW.

Indication

0

SGW’s node level Load Control Information

O

The SGW may include this IE, over the S11/S4 interface if the load control feature is supported by the SGW and is activated in the network (see clause 12.2.6).

When present, the SGW shall provide only one instance of this IE, representing its node level load information.

Load Control Information

0

SGW’s Overload Control Information

O

During an overload condition, the SGW may include this IE over the S5/S8 interface if the overload control feature is supported by the SGW and is activated for the PLMN to which the PGW belongs (see clause 12.3.11).

When present, the SGW shall provide only one instance of this IE, representing its overload information.

Overload Control Information

0

Paging and Service Information

CO

This IE shall be included on the S11 and S4 interfaces, for an IP PDN connection, if the SGW supports the Paging Policy Differentiation feature (see clause 4.9 of 3GPP TS 23.401 [3]) and if the Downlink Data Notification is triggered by the arrival of downlink data packets at the SGW. If the preceding conditions are fulfilled, then for each bearer and for each packet that triggers a Downlink Data Notification, the SGW shall copy, into the Paging Policy Indication value within this IE, the value of the DSCP in TOS (IPv4) or TC (IPv6) information received in the IP payload of the GTP-U packet from the PGW (see IETF RFC 2474 [65]).

See NOTE 4.

One IE with this type and instance value shall be included per EPS Bearers ID reported in the message,

See NOTE 1.

Paging and Service Information

0

DL Data Packets Size

CO

This IE shall be included on the S11 interfaces for a PDN connection if the MT-EDT is applicable and if the SGW supports MT-EDT feature as specified in clause 8.83.

When present, it shall contain the sum of DL Data Packets Size.

Integer Number

0

Private Extension

O

Private Extension

VS

NOTE 1: The usage of this parameter at the S4-SGSN is not specified in this release.

NOTE 2: In this version of the specification, the MME/S4-SGSN shall set the header TEID value in subsequent Downlink Data Notification Acknowledge or/and Downlink Data Notification Failure Indication to that of the SGW’s Control Plane TEID if the Sender F-TEID for Control Plane IE is present in the Downlink Data Notification message. However the SGW shall be prepared to receive messages in which the header TEID value is set to zero from implementation conforming to earlier versions of this specification. When that is the case, the receiver identifies the subscriber context based on the included IMSI IE.

NOTE 3: For PMIP based S5/S8, if the SGW cannot derive the EPS bearer ID/ARP from the control plane signalling (received over Gxx interface) the SGW should use the corresponding PDN connection’s (for which the control plane signalling is received) default EPS bearer’s EPS bearer ID/ARP.

NOTE 4: Upon receiving a downlink data packet for a Non-IP or Ethernet PDN connection (see clause 5.3.1 of 3GPP TS 23.401 [3]), the Paging and Service Information shall not be included in the Downlink Data Notification message.

Table 7.2.11.1-2: Load Control Information within Downlink Data Notification

Octet 1

Load Control Information IE Type = 181 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

Load Control Sequence Number

M

See clause 12.2.5.1.2.1 for the description and use of this parameter.

Sequence Number

0

Load Metric

M

See clause 12.2.5.1.2.2 for the description and use of this parameter.

Metric

0

Table 7.2.11.1-3: Overload Control Information within Downlink Data Notification

Octet 1

Overload Control Information IE Type = 180 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

Overload Control Sequence Number

M

See clause 12.3.5.1.2.1 for the description and use of this parameter.

Sequence Number

0

Overload Reduction Metric

M

See clause 12.3.5.1.2.3 for the description and use of this parameter.

Metric

0

Period of Validity

M

See clause 12.3.5.1.2.2 for the description and use of this parameter.

This IE should be set to "0" if the "Overload Reduction Metric" is null. This IE shall be ignored by the receiver if the "Overload Reduction Metric" is null.

EPC Timer

0

7.2.11.2 Downlink Data Notification Acknowledge

A Downlink Data Notification Acknowledge shall be sent from a MME/SGSN to a SGW in response to Downlink Data Notification with an indication of success, or failure when MME/SGSN has reachability or abnormal conditions.

Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

  • "Unable to page UE".
  • "Context not found".
  • "Unable to page UE due to Suspension".
  • "UE already re-attached".
  • "Temporarily rejected due to handover/TAU/RAU procedure in progress".

Table 7.2.11.2-1 specifies the presence of the IEs in the message.

Table 7.2.11.2-1: Information Elements in a Downlink Data Notification Acknowledge

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Data Notification Delay

C

he MME/SGSN shall include the delay the SGW shall apply between receiving downlink data and sending Downlink Data Notification for all UEs served by that MME/SGSN (see clause 5.3.4.2 of 3GPP TS 23.401 [3]), if the rate of Downlink Data Notification event occurrence in the MME/SGSN becomes significant (as configured by the operator) and the MME/SGSN’s load exceeds an operator configured value.

See NOTE 4.

Delay Value

0

Recovery

C

This IE shall be included if contacting the peer for the first time

Recovery

0

DL low priority traffic Throttling

O

The MME/SGSN may send this IE to the SGW to request the SGW to reduce the number of Downlink Data Notification requests it sends for downlink low priority traffic received for UEs in idle mode served by that MME/SGSN in proportion to the Throttling Factor and during the Throttling Delay.

See NOTE 1, NOTE 2, NOTE 3.

Throttling

0

IMSI

CO

3GPP TS 23.007 [17] specifies conditions for sending this IE on the S11/S4 interface as part of the network triggered service restoration procedure, if both the SGW and the MME/S4-SGSN support this optional feature.

IMSI

0

DL Buffering Duration

CO

The MME/SGSN shall include this IE on the S11/S4 interface to indicate the duration during which the SGW shall buffer DL data for this UE without sending any further Downlink Data Notification message, if extended buffering in the SGW is required:

  • for a UE in a power saving state (e.g. Power Saving Mode or extended idle mode DRX) that cannot be reached by paging at the moment, as specified in clause 5.3.4.3 of 3GPP TS 23.401 [3], or.
  • for a UE using NB-IoT, WB-EUTRAN or GERAN Extended Coverage with increased NAS transmission delay (see 3GPP TS 24.301 [23] and 3GPP TS 24.008 [5]).

If this IE is included in the message, the Cause IE shall be set to "Request Accepted".

EPC Timer

0

DL Buffering Suggested Packet Count

O

The MME/SGSN may include this IE on the S11/S4 interface, if the DL Buffering Duration IE is included, to suggest the maximum number of downlink data packets to be buffered in the SGW for this UE.

Integer Number

0

Private Extension

O

Private Extension

VS

NOTE 1: The last received value of the Throttling Factor and Throttling Delay shall supersede any previous values received from that MME/SGSN. The reception of a Throttling Delay shall restart the SGW timer associated with that MME/SGSN. The SGW shall determine whether a bearer is for low priority traffic or not on the basis of the bearer’s ARP priority level and operator policy (i.e. operator’s configuration in the SGW of the ARP priority levels to be considered as prioritary or non-prioritary traffic).

NOTE 2: For instance, if the DL low priority traffic Throttling IE indicates a Throttling Factor of 40% and a Throttling Delay of 180 seconds, the SGW drops by 40% the number of Downlink Data Notification requests it sends for downlink low priority traffic received for UEs in idle mode served by that MME/SGSN, during a period of 180 seconds.

NOTE 3: The DL low priority traffic Throttling IE may be present whatever the value of the Cause IE.

NOTE 4: The Data Notification Delay IE in the Data Notification Acknowledge has the same semantic and usage as the Delay Downlink Packet Notification Request IE in the Modify Bearer Request and Modify Access Bearers Request.

7.2.11.3 Downlink Data Notification Failure Indication

A Downlink Data Notification Failure indication shall be sent from an MME/SGSN to a SGW indicating that the UE did not respond to paging. It shall also be sent in the case that the UE responded to the page with a Service Request but that the MME has rejected the request by sending a Service Reject to the UE. It may happen, for example, because the requested service is not supported or there is a bearer context mismatch.

This message should not be used after an MME/SGSN successfully receives the Service Request message from the UE in the Network Triggered Service Request procedure as defined in the 3GPP TS 23.401 [3].

NOTE: Either the Modify Bearer Request message or the Delete Bearer Command message is used by the MME/SGSN to indicate a possible failure case after an MME/SGSN successfully receives the Service Request message from the UE.

Possible Cause values are:

  • "UE not responding".
  • "Service denied".
  • "UE already re-attached".

Table 7.2.11.3-1 specifies the presence of the IEs in the message.

Table 7.2.11.3-1: Information Elements in a Downlink Data Notification Failure Indication

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Originating Node

CO

This IE shall be included on the S4/S11 interface if the ISR associated GTP entities i.e. MME, S4-SGSN, send this message to the SGW during the Network Triggered Service Request procedure to denote the type of the node originating the message.

Node Type

0

IMSI

CO

3GPP TS 23.007 [17] specifies conditions for sending this IE on the S11/S4 interface as part of the network triggered service restoration procedure, if both the SGW and the MME/S4-SGSN support this optional feature.

IMSI

0

Private Extension

O

Private Extension

VS