5 Procedures Description
29.1283GPPMobility Management Entity (MME) and Serving GPRS Support Node (SGSN) interfaces for interworking with packet data networks and applicationsRelease 17TS
5.1 Introduction
This clause describes the Diameter-based T6a, T6b, T6ai, T6bi and T7 interface related procedures and the Information elements exchanged between the functional entities.
In the tables that describe the Information Elements transported by each Diameter command, each Information Element is marked as (M) Mandatory, (C) Conditional or (O) Optional in the "Cat." column. For the correct handling of the Information Element according to the category type, see the description detailed in clause 6 of the 3GPP TS 29.228 [6].
5.2 Report Procedures
5.2.1 General
This procedure is used between the MME/SGSN and the SCEF, between the MME/SGSN and the IWK-SCEF and between the IWK-SCEF and the SCEF.
When the procedure is invoked by the MME or the SGSN, it is used for reporting:
– UE Loss of Connectivity;
– UE Reachability;
– Location of the UE and change in location of the UE;
– Communication Failure;
– Availability after DNN failure;
– Idle Status Indication;
– PDN Connectivity Status.
When the procedure is invoked by the IWK-SCEF, it is used for conveying the monitoring event reported by the MME or the SGSN to the SCEF, after applying the roaming policies configured at the IWK-SCEF.
This procedure is mapped to the commands Reporting-Information-Request/Answer in the Diameter application specified in clause 6. The tables 5.2.1-1 and 5.2.1-2 detail the involved information elements.
Table 5.2.1-1: Reporting Information Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
User Identity (See 6.4.16) |
User-Identifier |
C |
If present, this information element shall contain the identity of the UE. This is a grouped AVP containing the MSISDN or the External-Identifier. |
Monitoring Event Report (see 3GPP TS 29.336 [5] clause 8.4.3) |
Monitoring-Event-Report |
C |
If the Reporting-Information-Request is sent for reporting the monitoring events, the MME/SGSN and the IWK-SCEF shall include the monitoring event(s) reported towards the SCEF. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Table 5.2.1-2: Reporting Information Answer
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
Result of the request. Result-Code AVP shall be used for errors defined in the Diameter Base Protocol. Experimental-Result AVP shall be used for T6a/b errors. This is a grouped AVP, which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Monitoring Event Report Status |
Monitoring-Event-Report-Status |
O |
If present, this information element shall contain the status of each individual monitoring event report received by the SCEF from the MME/SGSN. |
5.2.2 Detailed Behaviour of the MME/SGSN
5.2.2.0 General
The MME/SGSN shall fill the Monitoring-Event-Report AVP according to the event reported as specified below. For all monitoring events, the SCEF-ID, the SCEF-Reference-ID/SCEF-Reference-ID-Ext and the Monitoring-Type AVPs shall be included. In addition, the event specific AVPs as listed below shall be included based on the type of event reported.
The MME/SGSN shall include the External-Identifier or the MSISDN if present in the subscription data received from the HSS.
If the MME/SGSN receives an Experimental-Result-Code set to DIAMETER_ERROR_SCEF_REFERENCE_ID_UNKNOWN within an RIA command, it shall delete the event stored for the indicated SCEF-ID and SCEF-Reference-ID/SCEF-Reference-ID-Ext (see 3GPP TS 23.007 [19]).
5.2.2.1 UE Loss of Connectivity
The following AVPs shall be present within the Monitoring-Event-Report AVP when the UE Loss of Connectivity event is reported:
– Monitoring-Type set to LOSS_OF_CONNECTIVITY (0)
The following AVPs may be present within the Monitoring-Event-Report AVP when the UE Loss of Connectivity event is reported:
– Loss-Of-Connectivity-Reason set to one of the values defined in 3GPP TS 29.336 [5]
5.2.2.2 UE Reachability
The following AVPs shall be present within the Monitoring-Event-Report AVP when the UE Reachability event is reported:
– Monitoring-Type set to either UE_REACHABILITY (1) or UE_REACHABILITY_AND_IDLE_STATUS_INDICATION (8), as received in the configuration request.
– Reachability-Information set to REACHABLE_FOR_DATA(1)
The following AVPs may be present within the Monitoring-Event-Report AVP when the UE Reachability event is reported:
– Maximum-UE-Availability-Time
– Reachability-Cause
NOTE: When the Monitoring-Type is UE_REACHABILITY_AND_IDLE_STATUS_INDICATION (8), absence of the Idle-Status-Indication AVP from the Monitoring-Event-Report AVP indicates that UE reachability is reported.
5.2.2.3 Location Reporting
The following AVPs shall be present within the Monitoring-Event-Report AVP when the location event is reported:
– Monitoring-Type set to LOCATION_REPORTING (2)
– EPS-Location-Information
5.2.2.4 Communication Failure
The following AVPs shall be present within the Monitoring-Event-Report AVP when the Communication Failure event is reported
– Monitoring-Type set to COMMUNICATION_FAILURE (5)
– Communication-Failure-Information (see clause 6.4.3)
5.2.2.5 Availability after DDN failure
The following AVPs shall be present within the Monitoring-Event-Report AVP when the Availablability after DDN failure event is reported:
– Monitoring-Type set to either AVAILABILITY_AFTER_DDN_FAILURE (6) or AVAILABILITY_AFTER_DNN_FAILURE_AND_IDLE_STATUS_INDICATION (9), as received in the configuration request.
NOTE: When the Monitoring-Type is AVAILABILITY_AFTER_DNN_FAILURE_AND_IDLE_STATUS_INDICATION (9), absence of the Idle-Status-Indication AVP from the Monitoring-Event-Report AVP indicates that Availability after DNN failure is reported.
5.2.2.6 Idle Status Indication
The following AVPs shall be present within the Monitoring-Event-Report AVP when the Idle Status Indication event is reported:
– Monitoring-Type set to UE_REACHABILITY_AND_IDLE_STATUS_INDICATION (8) or to AVAILABILITY_AFTER_DDN_FAILURE_AND_IDLE_STATUS_INDICATION (9), depending on the Monitoring-Type of the corresponding event configuration.
– Idle-Status-Indication
5.2.2.7 PDN Connectivity Status
The following AVPs shall be present within the Monitoring-Event-Report AVP when the PDN Connectivity Status event is reported:
– Monitoring-Type set to PDN_CONNECTIVITY_STATUS (8)
– PDN-Connectivity-Status-Report
5.2.3 Detailed Behaviour of the SCEF
When the SCEF receives a Reporting Information Request from the MME/SGSN or the IWK-SCEF and at least one of the Monitoring Event Report AVPs has a SCEF-Reference-ID/SCEF-Reference-ID-Ext not known by the SCEF, it shall reply with Experimental-Result-Code set to DIAMETER_ERROR_SCEF_REFERENCE_ID_UNKNOWN (see 3GPP TS 23.007 [19]). In that case, if the HSS had included multiple Monitoring Event Reports in the RIR command, the SCEF shall include in the Reporting Information Answer command a list of Monitoring-Event-Report-Status AVPs where the status of multiple monitoring event reports is detailed. In that AVP list, the AVPs corresponding to event reports with a successful status may be omitted by the SCEF, for efficiency.
Otherwise when the SCEF receives a Reporting-Information-Request command from the MME/SGSN or the IWK-SCEF, the SCEF shall set Result-Code to DIAMETER_SUCCESS in the Reporting-Information-Answer and shall handle it according to the procedures defined in 3GPP TS 23.682 [2].
5.2.4 Detailed Behaviour of the IWK-SCEF
When the IWK-SCEF receives a Reporting-Information-Request command from the MME/SGSN it shall deliver the request to the SCEF after applying the roaming policies configured at the IWK-SCEF, as specified in 3GPP TS 23.682 [2].
5.3 Event Configuration Procedure
5.3.1 General
This procedure is used between the SCEF and the MME and between the SCEF and the SGSN to configure the monitoring events directly at the MME/SGSN through the T6a/b interface.
When the procedure is invoked by the SCEF, it is used for configuring the event(s):
– the number of UEs at a given geographic location.
This procedure is mapped to the commands Configuration-Information-Request/Answer in the Diameter application specified in clause 6. The tables 5.3.1-1 and 5.3.1-2 detail the involved information elements.
Table 5.3.1-1: Configuration Information Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Monitoring Event Configuration (see clause 6.4.2) |
Monitoring-Event-Configuration |
C |
If present, this Information Element shall contain the details of the Monitoring event(s) configured. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this Information Element shall contain the list of features supported by the origin host. |
Table 5.3.1-2: Configuration Information Answer
Information Element Name |
Mapping to Diameter AVP |
Cat |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
Result of the request. Result-Code AVP shall be used for errors defined in the Diameter Base Protocol. Experimental-Result AVP shall be used for T6a/T6b errors. This is a grouped AVP which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Monitoring Event Report (see 3GPP TS 29.336 [5] clause 8.4.3) |
Monitoring-Event-Report |
C |
If an immediate report is available this information element shall contain the requested data available in the MME/SGSN. |
Monitoring Event-Configuration Status (see 3GPP TS 29.336 [5] clause 8.4.24) |
Monitoring-Event-Config-Status |
O |
If present it shall contain the status of each monitoring event configuration identified by an SCEF-Reference-ID/SCEF-Reference-ID-Ext. |
5.3.2 Detailed Behaviour of the MME/SGSN
Monitoring Events configuration and deletion directly at the MME/SGSN for roaming scenarios is not supported. For the non roaming cases, when the Configuration-Information-Request is received from the SCEF, the MME/SGSN shall, in the following order:
1. Check whether the requesting SCEF is authorized to request the specified service (e.g: number of UEs at a given geographic location). If not, Experimental-Result-Code shall be set to DIAMETER_ERROR_UNAUTHORIZED_REQUESTING_ENTITY (5510) in the Configuration-Information-Answer.
2. If the TA / RA / ECGI location requested by the SCEF is not served by the MME/SGSN, then the MME/SGSN shall set the Experimental-Result AVP to DIAMETER_ERROR_REQUESTED_LOCATION_NOT_SERVED (5650) in the Configuration-Information-Answer.
If there is an error in any of the above steps then the MME/SGSN shall stop processing and shall return the error code specified in the respective step.
If the MME/SGSN cannot fulfil the received request for reasons not stated above, it shall stop processing the request and set Result-Code to DIAMETER_UNABLE_TO_COMPLY.
If CIR message includes multiple SCEF Reference IDs (either in SCEF-Reference-ID or in SCEF-Reference-ID-Ext AVPs) and for a SCEF Reference ID the monitoring events cannot be handled, the MME/SGSN shall report the failed SCEF Reference ID to the SCEF with an appropriate status in the Monitoring-Event-Config-Status AVP.
For the number of UEs in a geographic location monitoring event, for each SCEF-Reference-ID that the MME/SGSN is able to successfully process, the MME/SGSN shall
– if filtering is not requested (i.e. IMSI-Group-Id was not present in the request) or not supported:
include in the Configuration-Information-Answer, the exact count of the number of UEs that are known to be at the requested location.
– if filtering is requested and (i.e. IMSI-Group-Id was present in the request) and supported:
include in the Configuration-Information-Answer, the exact count of the number of UEs belonging to the provided IMSI Group that are known to be at the requested location.
If the requested location type is current location, then the MME/SGSN may activate the paging and RAN location reporting procedures (if required) before providing the response in the Configuration-Information-Answer.
If the monitoring event configuration is for a continuous monitoring (i.e. Monitoring-Duration and/or Maximum-Number-Of-Reports are set) and the deletion criteria are met (i.e. Monitoring-Duration time expired and/or Maximum-Number-Of-Reports are sent) the MME/SGSN shall locally delete the Monitoring event.
5.3.3 Detailed Behaviour of the IWK-SCEF
Monitoring Events configuration and deletion directly at the MME/SGSN for roaming scenarios is not supported. Consequently the IWK-SCEF is not impacted for Monitoring Events configuration and deletion directly at the MME/SGSN from the SCEF.5.3.4 Detailed Behaviour of the SCEF
When the SCEF receives Monitoring Event Report AVP from the MME/SGSN or the IWK-SCEF in the CIA command, it shall handle it according to the procedures defined in 3GPP TS 23.682 [2].
When the SCEF receives a Monitoring Event Report AVP from the MME/SGSN with a SCEF-Reference-ID/SCEF-Reference-ID-Ext not known by the SCEF, it should discard the Monitoring Event Report received in CIA command.
5.4 Event Configuration Procedure for Roaming
5.4.1 General
The MME/SGSN shall send the monitoring event configuration information to the IWK-SCEF in roaming scenarios, when the MME/SGSN receives the monitoring event configuration from the HSS. The monitoring event configuration information shall be locally consumed at the IWK-SCEF and the IWK-SCEF shall not route such requests beyond it.
This procedure is mapped to the commands Configuration-Information-Request/Answer in the Diameter application specified in clause 6. The tables 5.4.1-1 and 5.4.1-2 detail the involved information elements.
Table 5.4.1-1: Configuration-Information-Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Monitoring Event Configuration (see 8.4.2) |
Monitoring-Event-Configuration |
C |
If present, this Information Element shall contain the details of Monitoring event(s). |
Monitoring Event Report (see 8.4.3) |
Monitoring-Event-Report |
C |
If an immediate report is available this information element shall contain the event reported by the MME/SGSN. The IWK-SCEF may normalize the event report and return it in the Configuration-Information-Answer. |
Supported Features (See 3GPP TS 29.229 [7]) |
Supported-Features |
O |
If present, this Information Element shall contain the list of features supported by the origin host. |
Table 5.4.1-2: Configuration-Information-Answer
Information Element Name |
Mapping to Diameter AVP |
Cat |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
Result of the request. Result-Code AVP shall be used for errors defined in the Diameter Base Protocol. Experimental-Result AVP shall be used for T6a/b errors. This is a grouped AVP which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
Supported Features (See 3GPP TS 29.229 [7]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Monitoring Event-Configuration Status (see 3GPP TS 29.336 [5] clause 8.4.24) |
Monitoring-Event-Config-Status |
O |
If present it shall contain the status of each monitoring event configuration identified by an SCEF-Reference-ID/SCEF-Reference-ID-Ext. |
5.4.2 Detailed Behaviour of the IWK-SCEF
When the Configuration-Information-Request is received from the MME/SGSN, the IWK-SCEF shall, in the following order:
1. Check whether the requesting SCEF, identified by the SCEF-ID is authorized to request the specified service at the VPLMN. If not, Experimental-Result shall be set to DIAMETER_ERROR_UNAUTHORIZED_REQUESTING_ENTITY (5510) in the Configuration-Information-Answer.
2. Check whether the chargeable party for the monitoring event is authorized to be charged at the VPLMN. If not, Experimental-Result shall be set to DIAMETER_ERROR_UNAUTHORIZED_REQUESTING_ENTITY (5510) in the Configuration-Information-Answer.
If the monitoring event configuration also carries the monitoring event report, the IWK-SCEF checks if the immediate events reported by the MME/SGSN needs to be normalized. If yes, the IWK-SCEF shall normalize the event report as per local policies. The IWK-SCEF shall then send the normalized monitoring event report towards the SCEF as a separate Reporting-Information-Request message.
If the monitoring event configuration is for a continuous monitoring (i.e. Monitoring-Duration and/or Maximum-Number-Of-Reports are set), then the IWK-SCEF shall temporarily store the monitoring event configuration until the deletion criteria for the monitoring event configuration is met. If the deletion criteria are met, the IWK-SCEF shall delete the Monitoring event locally. The stored monitoring event configuration information shall be used during subsequent monitoring event report procedure, to generate the charging records towards the right chargeable party.
If the received SCEF Reference ID for Deletion (either in SCEF-Reference-ID-for-Deletion or in SCEF-Reference-ID-for-Deletion-Ext AVPs) does not exist, the IWK-SCEF shall set the Experimental-Result-Code to DIAMETER_ERROR_CONFIGURATION_EVENT_NON_EXISTANT (5514).
If the SCEF Reference ID (either in SCEF-Reference-ID or in SCEF-Reference-ID-Ext) exists and the old configuration data could not be replaced by new Configuration event data, the HSS shall set the Experimental-Result-Code to DIAMETER_ERROR_CONFIGURATION_EVENT_STORAGE_NOT_SUCCESSFUL (5513).
If the IWK-SCEF cannot fulfil the received request for reasons not stated in the above, it shall stop processing the request and set Result-Code to DIAMETER_UNABLE_TO_COMPLY.
The details how to handle expiring of Monitoring events is described in 3GPP TS 23.682 [2]
5.4.3 Detailed Behaviour of the MME/SGSN
When the MME/SGSN receives the Configuration-Information-Answer from the IWK-SCEF, it shall handle it as follows: For the monitoring event configurations for which the configuration status have changed since last informed to the HSS, the MME/SGSN shall report the status to the HSS through a Notify-Request command as specified in clause 5.2.5 of 3GPP TS 29.272 [16].
5.5 MO-Data Procedure
5.5.1 General
This procedure shall be used between the MME/SGSN and the SCEF, between the MME/SGSN and the IWK-SCEF and between the IWK-SCEF and the SCEF.
When the procedure is invoked by the MME or SGSN, it is used to forward mobile originated Non-IP data of a mobile user from the MME or SGSN to the SCEF. The procedure is also invoked by the MME on reception of RRC cause "MO Exception data".
This procedure is used according to 3GPP TS 23.682 [2] clause 5.13.4.
The IWK-SCEF may be in the path between the MME/SGSN and the SCEF for roaming cases when the IWK-SCEF is deployed by the operator of the visited PLMN.
When the procedure is invoked by the IWK-SCEF, it is used to forward mobile originated Non-IP data received from the MME or SGSN to the SCEF.
This procedure is mapped to the commands MO-Data-Request/Answer (ODR/ODA) in the Diameter application specified in clause 6.
The tables 5.5.1-1 and 5.5.1-2 detail the involved information elements.
Table 5.5.1-1: MO Data Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
User Identity (See 6.4.16) |
User-Identifier |
M |
This Information Element shall be present and shall contain the identity of the UE. This is a grouped AVP which shall contain the IMSI. |
EPS Bearer Identity (See 6.4.17) |
Bearer-Identifier |
M |
This information element shall be present and shall contain either the identity of the EPS bearer identifying the T6a connection, or the NSAPI of the PDP context identifying the T6b connection, for the Non-IP data delivery. |
Non IP data (See 6.4.19) |
Non-IP-Data |
C |
This information element shall contain the Non-IP data to be delivered to the SCEF. This Information Element shall be present when the request conveys Non-IP data. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
MO Exception Data Counter (see 6.4.27) |
RRC-Cause-Counter |
C |
The MME shall include this Information Element when MME needs to send a non-zero counter value for the MO Exception Data Counter. The timestamp in the counter shall be set with the time at which the counter value increased from 0 to 1. |
Table 5.5.1-2: MO Data Answer
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
Result of the request. Result-Code AVP shall be used for errors defined in the Diameter Base Protocol. Experimental-Result AVP shall be used for T6a/b errors. This is a grouped AVP, which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
5.5.2 Detailed Behaviour of the MME/SGSN
The MME shall make use of this procedure over a T6a connection identified by its EPS bearer identity and previously established with the SCEF to forward the Non-IP data received from the UE to the SCEF or to an IWK-SCEF when deployed for a roaming case.
The SGSN shall make use of this procedure over a T6b connection identified by the NSAPI of the PDP context, and previously established with the SCEF, to forward the Non-IP data received from the UE to the SCEF or to an IWK-SCEF when deployed for a roaming case.
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 MO Data command message to report a non-zero value for the MO Exception Data Counter based on local configuration.
If the MME has sent the RRC-Cause-Counter for RRC Cause "MO Exception data" in the MO Data Request command the MME shall reset the RRC-Cause-Counter when receiving MO Data Answer command.
When receiving a Permanent Failure Result-Code/Experimental-Result, the MME or SGSN shall initiate a PDN disconnection procedure or Detach procedure towards the UE and if the permanent failure is different from DIAMETER_ERROR_ INVALID_EPS_BEARER and different from DIAMETER_ERROR_USER_UNKNOWN, the MME or SGSN shall make use of the "Connection Management by MME/SGSN" Procedure (see clause 5.7) to release the T6a/b connection between the MME/SGSN and the SCEF.
5.5.3 Detailed Behaviour of the SCEF
When the SCEF receives a MO Data Request from the MME/SGSN or the IWK-SCEF, the SCEF shall, in the following order:
– Check that the User Identity exists in the SCEF. If not, Experimental-Result shall be set to DIAMETER_ERROR_USER_UNKNOWN in the MO Data Answer;
– Check if, for this user, a bearer context exists. If not, Experimental-Result shall be set to DIAMETER_ERROR_ INVALID_EPS_BEARER in the MO Data Answer;
– Process the delivery of the data (if available) to the SCS/AS and/or process the RRC Cause Counter (if available). If the processing of either of them is not successful, return an appropriate Diameter error code, otherwise return a Result code set to DIAMETER_SUCCESS to the MME/SGSN or IWK-SCEF. If the data delivery to the SCS/AS has failed due to there being no NIDD configuration context with an SCS/AS, set the Experimental-Result to DIAMETER_ERROR_NIDD_CONFIGURATION_NOT_AVAILABLE in the MO Data Answer.
NOTE: The Diameter Result-Code / Experimental-Result returned by the SCEF can depend on the error returned by the SCS/AS to the SCEF. The interface between the SCEF and the SCS/AS is out of scope of 3GPP.
5.5.4 Detailed Behaviour of the IWK-SCEF
When the IWK-SCEF receives a MO Data Request from the MME or SGSN, it shall forward the request to the SCEF.
When the IWK-SCEF receives a MO Data Answer from the SCEF, it shall forward the answer to the MME or SGSN.
5.6 MT Data Procedure
5.6.1 General
This procedure shall be used between the SCEF and the MME or SGSN, between the SCEF and the IWK-SCEF and between the IWK-SCEF and the MME or SGSN.
When the procedure is invoked by the SCEF, it is used to forward mobile terminated Non-IP data of a mobile user from the SCEF to the MME or SGSN.
This procedure is used according to 3GPP TS 23.682 [2] clause 5.13.3.
The IWK-SCEF may be in the path between the SCEF and the MME/SGSN for roaming cases when the IWK-SCEF is deployed by the operator of the visited PLMN.
When the procedure is invoked by the IWK-SCEF, it is used to forward mobile terminated Non-IP data received from the SCEF to the MME or SGSN.
This procedure is mapped to the commands MT-Data-Request/Answer (TDR/TDA) in the Diameter application specified in clause 6.
The tables 5.6.1-1 and 5.6.1-2 detail the involved information elements.
NOTE: The corresponding message name in 3GPP TS 23.682 [2] is "NIDD Submit Request".
Table 5.6.1-1: MT Data Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
User Identity (See 6.4.16) |
User-Identifier |
M |
This Information Element shall be present and shall contain the identity of the UE. This is a grouped AVP which shall contain the IMSI. |
EPS Bearer Identity (See 6.4.17) |
Bearer-Identifier |
M |
This information element shall be present and shall contain either the identity of the EPS bearer identifying the T6a connection, or the NSAPI of the PDP context identifying the T6b connection, for the Non-IP data delivery. |
Non-IP Data (See 6.4.19) |
Non-IP-Data |
C |
This information element shall contain the Non-IP data to be delivered to the MME or SGSN. This Information Element shall be present when the request conveys Non-IP data. |
SCEF Wait Time (See 6.4.24) |
SCEF-Wait-Time |
O |
This information element, when present, shall indicate the timestamp (in UTC) until which the SCEF expects a response. |
Maximum Retransmission Time (See 3GPP TS 29.338 [27]) |
Maximum-Retransmission-Time |
O |
This information element, when present, shall indicate the maximum retransmission time (in UTC) until which the SCEF is capable to retransmit the MT Non-IP Data. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Table 5.6.1-2: MT Data Answer
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
This information element shall contain the Result of the request. The Result-Code AVP shall be used to indicate success or errors as defined in the Diameter Base Protocol. The Experimental-Result AVP shall be used for T6a/b errors. This is a grouped AVP, which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
Requested Retransmission Time (See 3GPP TS 29.338 [27]) |
Requested-Retransmission-Time |
O |
This information element may be present if the Experimental-Result-Code is set to DIAMETER_ERROR_USER_TEMPORARILY_UNREACHABLE and the Maximum Retransmission Time information element is present in the MT Data Request. It may be included if the UE is using a power saving mechanism (such as extended idle mode DRX) and the UE is currently not reachable. When present, this shall indicate the retransmission time (in UTC) at which the SCEF is requested to retransmit the MT Non-IP Data. The Requested Retransmission Time shall not exceed the Maximum Retransmission Time received from the SCEF. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
TDA Flags (See 6.4.31) |
TDA-Flags |
O |
This Information Element contains a bit mask. See clause 6.4.31 for the meaning of the bits and the condition for each bit to be set or not. |
5.6.2 Detailed Behaviour of the SCEF
The SCEF shall make use of this procedure over a T6a connection identified by its EPS Bearer Identity, and previously established with the MME, to forward the Non-IP data received from the SCS/AS to the MME or to an IWK-SCEF when deployed for a roaming case.
The SCEF shall make use of this procedure over a T6b connection identified by the NSAPI of the PDP context, and previously established with the SGSN, to forward the Non-IP data received from the SCS/AS to the SGSN or to an IWK-SCEF when deployed for a roaming case.
The SCEF shall check if a bearer context exists for the user before sending the request.
The SCEF may include the Maximum-Retransmission-Time AVP in the MT Data Request to indicate the maximum retransmission time for when it is capable to retransmit the Non-IP Data.
If the MT Data Answer includes the Requested-Retransmission-Time AVP, the SCEF shall retransmit the MT Non-IP Data at the requested retransmission time.
5.6.3 Detailed Behaviour of the MME/SGSN
When the MME or SGSN receives a MT Data Request from the SCEF or the IWK-SCEF, the MME or SGSN shall, in the following order:
– Check that the User Identity exists in the MME or SGSN. If not, Experimental-Result shall be set to DIAMETER_ERROR_USER_UNKNOWN in the MT Data Answer;
– Check whether, for this user, a bearer context exists. If not, Experimental-Result shall be set to DIAMETER_ERROR_ INVALID_EPS_BEARER in the MT Data Answer.
– Process the data delivery to the UE and:
– if it is successful, return a Result code set to DIAMETER_SUCCESS to the SCEF or IWK-SCEF; in addition, if the successful delivery was acknowledged by the eNodeB, the MME/SGSN shall set the "Success Acknowledged Delivery" bit within the TDA-Flags AVP.
– return an Experimental-Result set to DIAMETER_ERROR_USER_TEMPORARILY_UNREACHABLE, if the UE is using a power saving function (e.g. extended idle mode DRX or UE Power Saving Mode as defined in 3GPP TS 23.682 [27]) and the UE is expected to not be reachable shortly or, based on MME or SGSN implementation, within the time indicated by the SCEF-Wait-Time;
The MME or SGSN shall set the Not Reachable for NIDD flag and store the SCEF Host and Realm for which this flag is set;
If the MT Data Request includes the Maximum-Retransmission-Time AVP, the MME or SGSN may additionally include the Requested-Retransmission-Time AVP requesting the SCEF to retransmit the Non-IP Data at a later time prior to the Maximum Retransmission Time;
The MME or SGSN shall then update the SCEF, as specified in clause 5.7, when it detects that the UE is reachable or about to become reachable and the Not Reachable for NIDD flag is set. If the MME or SGSN included the Requested-Retransmission-Time AVP in the MT Data Answer, the MME or SGSN shall do so only if the UE becomes reachable before the Requested Retransmission Time, i.e. the MME or SGSN shall reset the Not Reachable for NIDD flag when the Requested-Retransmission-Time expires if the UE has not become reachable beforehand;
– return an Experimental-Result set to DIAMETER_ERROR_UNREACHABLE_USER, if the UE is not reachable;
– otherwise return an appropriate Diameter error code.
5.6.4 Detailed Behaviour of the IWK-SCEF
When the IWK-SCEF receives a MT Data Request from the SCEF, it shall forward the request to the MME or SGSN.
When the IWK-SCEF receives a MT Data Answer from the MME or SGSN, it shall forward the answer to the SCEF.
5.7 Connection Management by MME/SGSN Procedure.
5.7.1 General
This procedure shall be used between the MME/SGSN and the SCEF, between the MME/SGSN and the IWK-SCEF and between the IWK-SCEF and the SCEF.
When the procedure is invoked by the MME or SGSN, it is used:
– to establish a T6a/b connection between the MME/SGSN and the SCEF;
– to update the parameters (e.g. RAT-Type) for a T6a/b connection between the MME/SGSN and the SCEF;
– to update the status of a T6a/b connection between the MME/SGSN and the SCEF, e.g. to indicate to the SCEF that the UE has become or is about to become reachable when MT non-IP data is pending at the SCEF for a UE using a power saving function;
This procedure is used according to 3GPP TS 23.682 [2] clause 5.13.1 and 5.13.5 and 5.13.6. The IWK-SCEF may be in the path between the MME/SGSN and the SCEF for roaming cases when the IWK-SCEF is deployed by the operator of the visited PLMN.
When the procedure is invoked by the IWK-SCEF, it is used to forward the Connection Management Request received from the MME or SGSN to the SCEF.
This procedure is mapped to the commands Connection-Management-Request/Answer (CMR/CMA) in the Diameter application specified in clause 6.
The tables 5.7.1-1 and 5.7.1-2 detail the involved information elements.
Table 5.7.1-1: Connection Management Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
User Identity (See 6.4.16) |
User-Identifier |
M |
This Information Element shall be present and shall contain the identity of the UE. This is a grouped AVP which shall contain the IMSI. |
EPS Bearer Identity (See 6.4.17) |
Bearer-Identifier |
M |
This Information Element shall be present and shall contain either the identity of the EPS bearer identifying the T6a connection, or the NSAPI of the PDP context of the T6b connection, to which the request applies. |
T6a/b Connection Action (See 6.4.18) |
Connection-Action |
M |
This Information element shall be present and shall contain a T6a/b connection management action indicating a T6a/b connection establishment or a T6a/b connection release or a T6a/b connection update. |
APN (See 6.4.20) |
Service-Selection |
C |
This Information element shall contain the APN the user wants to connect to. It shall be present if the request is for a T6a/b connection establishment. |
Serving PLMN Rate Control (See 6.4.21) |
Serving-PLMN-Rate-Control |
O |
If present, this information element shall contain the Serving PLMN rate control set by the MME. |
CMR Flags (See 6.4.25) |
CMR-Flags |
O |
This Information Element contains a bit mask. See clause 6.4.25 for the meaning of the bits and the condition for each bit to be set or not. |
Maximum UE Availability Time (See 3GPP TS 29.338 [27]) |
Maximum-UE-Availability-Time |
O |
This information element may be included, if available, if the Connection-Action AVP indicates a T6a/b connection update and the UE-Reachable-Indicator is set in the CMR-Flags AVP. When present, it shall indicate the timestamp (in UTC) until which a UE using a power saving mechanism (such as extended idle mode DRX) is expected to be reachable for MT Non-IP Data Delivery. This information may be used by the SCEF to prioritize the retransmission of MT Non-IP Data to UEs using a power saving mechanism. |
Extended PCO |
Extended-PCO |
C |
This Information Element shall be present, if the MME or SGSN receives Extended PCO information from the UE. |
3GPP Charging Characteristics (See 3GPP TS 32.298 [30] |
3GPP-Charging-Characteristics |
C |
This Information element shall contain the PDN Connection Charging Characteristics data for an APN Configuration with SCEF-based NIDD mechanism. It shall be present if the request is for a T6a/b connection establishment and may be present if the request is for a T6a/b connection update. |
RAT-Type (See 3GPP TS 29.212 [10]) |
RAT-Type |
C |
This Information Element shall contain the used RAT Type. It shall be present if the request is for a T6a/b connection establishment or for a T6a/b connection update. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Terminal Information (See 3GPP TS 29.272 [16]) |
Terminal-Information |
C |
This Information Element shall contain the identity of the UE. It shall be present if available. |
Visited PLMN ID (See 3GPP TS 29.272 [16]) |
Visited-PLMN-Id |
C |
This Information Element shall contain the identity (MCC and MNC) of serving PLMN. It shall be present if the request is for a T6a/b connection establishment or for a T6a/b connection update. |
APN Rate Control Status (see 6.4.36) |
APN-Rate-Control-Status |
O |
May be present if the request is for a T6a/b connection establishment. |
Table 5.7.1-2: Connection Management Answer
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
Result of the request. Result-Code AVP shall be used for errors defined in the Diameter Base Protocol. Experimental-Result AVP shall be used for T6a/b errors. This is a grouped AVP, which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
NIDD Charging Identifier (See 3GPP TS 32.299 [22]) |
PDN-Connection-Charging-Id |
C |
This Information element is defined in 3GPP TS 32.253 [23] and shall be present if the answer is for a T6a/b connection establishment. |
Extended PCO |
Extended-PCO |
C |
This Information Element shall be present, if the SCEF needs to send Extended PCO information to the UE. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
APN Rate Control Status (see 6.4.36) |
APN-Rate-Control-Status |
O |
May be present if the response is for a T6a/b connection release. |
5.7.2 Detailed Behaviour of the MME/SGSN
The MME or SGSN shall make use of this procedure to request one of the following T6a/b connection management actions:
– for a T6a/b connection establishment, the MME shall:
– include the user’s IMSI.
– fill the EPS Bearer Identity information element with either the identity of the EPS bearer that MME allocated to the Non-IP PDN connection, or the NSAPI of the PDP context used by the SGSN for the Non-IP connection, as described in 3GPP TS 23.682 [2];
– if Serving PLMN Rate Control is configured, the MME shall include the Serving PLMN Rate Control information as described in 3GPP TS 23.401 [25];
– for a T6a/b connection release, the MME or SGSN shall:
– fill the EPS Bearer Identity information element with the identity of the EPS bearer of the T6a connection, or the NSAPI of the PDP context of the T6b connection, which is released as described in 3GPP TS 23.682 [2];
– upon getting the Connection Management Answer from the SCEF, delete the T6a/b connection context;
– for a T6a/b connection update, the MME or SGSN shall:
– fill the EPS Bearer Identity information element with the identity of the EPS bearer of the T6a connection, or the NSAPI of the PDP context of the T6b connection, that needs to be updated;
– set the UE-Reachable-Indicator in the CMR-Flags AVP if the UE has become or is about to become reachable. The MME or SGSN may additionally include the Maximum UE Availability Time AVP, if available, to indicate the timestamp (in UTC) until which a UE using a power saving mechanism (such as extended idle mode DRX) is expected to be reachable for MT Non-IP Data Delivery;
– upon getting the Connection Management Answer from the SCEF, reset the Not Reachable for NIDD flag if this flag was set and if the UE-Reachable-Indicator was set in the CMR-Flags AVP in the Connection Management Request;
– if Serving PLMN Rate Control needs to be added or updated, the MME shall include Serving PLMN Rate Control information as described in 3GPP TS 23.401 [25].
NOTE: If the UE has several T6a/b connections to the same SCEF, for which Non-IP data is pending, the MME or SGSN initiates a T6a/b connection update for only one of the T6a/b connections towards this SCEF; the UE can have either T6a or T6b connections, but not both simultaneously.
If the MME or SGSN receives the Extended-PCO AVP in the Connection Management Answer from the SCEF, the MME or SGSN shall forward the Extended-PCO to the UE transparently, as specified in 3GPP TS 24.301 [28].
5.7.3 Detailed Behaviour of the SCEF
When the SCEF receives a Connection Management Request from the MME or SGSN the SCEF shall, in the following order:
– check that the User Identity exists in the SCEF. If not, Experimental-Result shall be set to DIAMETER_ERROR_USER_UNKNOWN in the Connection Management Answer;
– check that the T6a/b connection action indicates a T6a/b connection establishment, a T6a/b connection release or a T6a/b connection update. If not, the Experimental-Result shall be set to DIAMETER_ERROR_OPERATION_NOT_ALLOWED in the Connection Management Answer;
– if the T6a/b connection action indicates a T6a/b connection establishment:
– check whether a valid NIDD configuration exists for the UE at the SCEF;
If not, the SCEF shall:
– reject the Connection Management Request, with Experimental-Result set to DIAMETER_ERROR_NIDD_CONFIGURATION_NOT_AVAILABLE in the Connection Management Answer, or
– accept the Connection Management Request, and initiate a NIDD Configuration procedure with a default SCS/AS configured in the SCEF and the MSISDN or an external ID obtained from the HSS, as specified in 3GPP TS 29.336 [5] clause 7.2.3.2. If such NIDD Configuration procedure fails, the SCEF shall reject the Connection Management Request, with Experimental-Result set to DIAMETER_ERROR_NIDD_CONFIGURATION_NOT_AVAILABLE in the Connection Management Answer;
– create an EPS bearer context;
– store the MME or SGSN Identity identified by the Origin-Host AVP of the T6a/b Connection Management Request, and the MME or SGSN realm identified by the Origin-Realm AVP of the T6a/b Connection Management Request in the EPS bearer context;
– include the Extended-PCO AVP in the Connection Management Answer, if the Extended PCO information (e.g. APN Rate Control information) needs to be provided to the UE;
– if Serving PLMN Rate Control is provided by the MME, restrict the number of messages for the downlink to not exceed the values provided in Serving PLMN Rate Control. If it is not provided and Serving PLMN Rate Control is active, then continue using the previously provided values;
– If successful, Result shall be set to DIAMETER_SUCCESS in the Connection Management Answer;
– if the T6a/b connection action indicates a T6a/b connection release:
– check whether, for this user and the received EPS bearer ID, a T6a connection context exists. If not, Experimental-Result shall be set to DIAMETER_ERROR_INVALID_EPS_BEARER in the Connection Management Answer;
– include the Extended-PCO AVP in the Connection Management Answer, if the Extended PCO information needs to be provided to the UE;
– delete the T6a/b connection context at the SCEF. If successful, Result code shall be set to DIAMETER_SUCCESS in the Connection Management Answer;
– if the T6a/b connection action indicates a T6a connection update:
– check whether, for this user and the received EPS Bearer Identity, a T6a/b connection context exists. If not, Experimental-Result shall be set to DIAMETER_ERROR_INVALID_EPS_BEARER in the Connection Management Answer;
– if successful:
– if Serving PLMN Rate Control is provided by the MME, restrict the number of messages for the downlink to not exceed the values provided in Serving PLMN Rate Control. If it is not provided and Serving PLMN Rate Control is active, then continue using the previously provided values;
– include the Extended-PCO AVP in the Connection Management Answer, if the Extended PCO information (e.g. APN Rate Control information) needs to be provided to the UE;
– store the MME or SGSN Identity identified by the Origin-Host AVP of the T6a/b Connection Management Request and the MME or SGSN realm identified by the Origin-Realm AVP of the T6a/b Connection Management Request, if the MME or SGSN identity has changed, in the bearer context, and the Result shall be set to DIAMETER_SUCCESS in the Connection Management Answer;
– if the UE-Reachable-Indicator was set in the CMR-Flags AVP, forward any MT Non-IP data pending for any T6a/b connection for this UE, to the MME or SGSN.
If the Serving-PLMN-Rate-Control AVP is included in the Connection Management Request message from the MME, the SCEF shall enforce the Serving PLMN Rate Control as specified in 3GPP TS 23.401 [12] clause 4.7.7.2.
5.7.4 Detailed Behaviour of the IWK-SCEF
When the IWK-SCEF receives a Connection Management Request from the MME or SGSN, it shall forward the request to the SCEF.
When the IWK-SCEF receives a Connection Management Answer from the SCEF, it shall forward the answer to the MME or SGSN.
5.8 Connection Management by SCEF Procedure
5.8.1 General
This procedure shall be used between the SCEF and the MME/SGSN, and between the SCEF and the MME/SGSN via the IWK-SCEF acting as a Diameter proxy agent for roaming cases.
When the procedure is invoked by the SCEF, it is used
– to update the parameters (e.g. Extended PCO information) associated to a T6a/b connection between the MME/SGSN and the SCEF;
– to release a T6a/b connection between MME/SGSN and SCEF.
This procedure is used according to 3GPP TS 23.682 [2]. The IWK-SCEF may be in the path between the MME/SGSN and the SCEF for roaming cases when the IWK-SCEF is deployed by the operator of the visited PLMN.
This procedure is mapped to the commands Connection-Management-Request/Answer (CMR/CMA) in the Diameter application specified in clause 6.
The tables 5.8.1-1 and 5.8.1-2 detail the involved information elements.
Table 5.8.1-1: Connection Management SCEF Request
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
User Identity (See 6.4.16) |
User-Identifier |
M |
This Information Element shall be present and shall contain the identity of the UE. This is a grouped AVP containing the IMSI. |
EPS Bearer Identity (See 6.4.17) |
Bearer-Identifier |
M |
This Information Element shall be present and shall contain either the identity of the EPS bearer identifying the T6a connection, or the NSAPI of the PDP context identifying the T6b connection, to which the request applies. |
T6a/b Connection Action (See 6.4.18) |
Connection-Action |
M |
This Information element shall be present and shall contain a T6a/b connection management action indicating a T6a/b connection update. |
Extended PCO (see 6.4.26) |
Extended-PCO |
C |
This Information Element shall be present if the SCEF needs to send updated Extended PCO information (e.g. APN Rate Control information) to the UE. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
Table 5.8.1-2: Connection Management SCEF Answer
Information Element Name |
Mapping to Diameter AVP |
Cat. |
Description |
Result (See 6.3) |
Result-Code / Experimental-Result |
M |
Result of the request. Result-Code AVP shall be used for errors defined in the Diameter Base Protocol. Experimental-Result AVP shall be used for T6a/b errors. This is a grouped AVP, which contains the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. |
Supported Features (See 3GPP TS 29.229 [4]) |
Supported-Features |
O |
If present, this information element shall contain the list of features supported by the origin host. |
5.8.2 Detailed Behaviour of the SCEF
The SCEF shall make use of this procedure to send the updated Extended PCO information (e.g. APN Rate Control information) to the UE during T6a/b connection update, if needed. If APN Rate Control Control information is included in the Extended-PCO AVP within the Connection Management SCEF Request message from the SCEF, the SCEF shall enforce the APN Rate Control as specified in 3GPP TS 23.401 [12] clause 4.7.7.3.
The SCEF shall make use of this procedure to request the release of the T6a/b connection.
5.8.3 Detailed Behaviour of the MME/SGSN
When the MME or SGSN receives a Connection Management SCEF Request from the SCEF or the IWK-SCEF, the MME or SGSN shall, in the following order:
– check that the User Identity exists in the MME or SGSN. If not, Experimental-Result shall be set to DIAMETER_ERROR_USER_UNKNOWN in the Connection Management SCEF Answer;
– check that the T6a/b connection action indicates a T6a/b connection update or T6a/b connection release. If not, the Experimental-Result shall be set to DIAMETER_ERROR_OPERATION_NOT_ALLOWED in the Connection Management SCEF Answer;
– check whether, for this user and the received EPS Bearer Identity, a T6a/b connection context exists. If not, Experimental-Result shall be set to DIAMETER_ERROR_ INVALID_EPS_BEARER in the Connection Management SCEF Answer;
– if the T6a/b connection action indicates a T6a/b connection update:
– if the Extended-PCO AVP is received, forward the Extended-PCO to the UE, as specified in 3GPP TS 24.301[28]. If successful, the Result code shall be set to DIAMETER_SUCCESS in the Connection Management SCEF Answer.
– if the T6a/b connection action indicates T6a/b connection release, delete the T6a/b connection context at the MME/SGSN. If successful, the Result code shall be set to DIAMETER_SUCCESS in the Connection Management SCEF Answer.
5.8.4 Detailed Behaviour of the IWK-SCEF
When the IWK-SCEF receives a Connection Management SCEF Request from the SCEF, it shall forward the request to the MME or SGSN.
When the IWK-SCEF receives a Connection Management SCEF Answer from the MME or SGSN, it shall forward the answer to the SCEF.