SMF

Event Failure Logs

SMF provides the following support:

• Consistent event failure logs for Create, and Idle or Active procedures across pods

• Configurable logs at pod type

• Inclusion of request and response details in a single-line format

The consistent error log message format across various pods helps in analytics and minimized number of log generations by the system. The single-line log format display enhances the readability.

Default Setting: Not applicable

Ga/N40 Interface Enhancement for correlation of the CGF Feeds

This feature enables GTPP-EP to support the CHF record with ASN1 encoding and send the record to the configured CGF server through GTPP protocol. GTPP-EP additionally supports the base features for CHF record, such as batcher for GTPP records, archival, peer management, and CGF selection.

This feature will be consumed by the CHF service by invoking new APIs to send the GTPP CHF records.

P-CSCF Address Restoration and Re-Selection

SMF supports restoration and reselection of P-CSCF addresses when a P-CSCF failure event occurs. The CLI pcscf-restoration trigger [ UDM ][ action [ mark-down ]] is used for configuring P-CSCF address reselection.

This feature enables the 5G/4G/Wi-Fi RAT subscribers to restore a failed IMS connectivity with UE by connecting to a working P-CSCF address.

Default Setting: Disabled – Configuration required to enable

Preemptive Quota Requests for Static and Predefined Rules

In SMF, Preemptive Quota is enabled by default for dynamic rules.

Through this feature enhancement, SMF can request preemptive quota for static and predefined rules during the initial attach session creation procedure.

The preemptive quota is configurable using the preemptively-request-n-validate command in the Charging Action Configuration mode.

Default Setting: Enabled – Always-on

Rolling Upgrade Optimization

Converged Core Gateway provides the following support:

• Retry mechanism at service and protocol pods during upgrades

• Configuration-based rolling upgrade enhancements

This optimization helps in reduced session and Call Events Per Second (CEPS) loss during the upgrade procedure. The configurable rolling upgrade enhancements enable smooth rollout of the changes.

This feature introduces the new CLI command supported-features [ app-rx-retx-cache | app-tx-retx | rolling-upgrade-all | rolling-upgrade-enhancement-infra ] in the converged core profile.

Default Setting: Disabled – Configuration required to enable

Selection of Alternate AMF

This feature allows the SMF to choose an available AMF from the set when the AMF connected to the UE experiences an outage. SMF performs AMF selection based on the configuration of query parameters or NRF query response local filters.

This feature addresses the need for uninterrupted service continuity in the event of an AMF becoming unavailable.

This feature introduces the following new CLI commands:

• filter-discovery-response filter match { all | any } attributes { target-nf-instance-id }

• filter-discovery-response filter failure-action { use-discovery-response }

These configurations allow SMF to locally filter the received NRF discovery response and select the appropriate one which matches the configured filters.

This feature additionally supports region and set ID configuration as part of NRF query parameters.

Default Setting: Disabled – Configuration required to enable

Mobile IoT

DNN Inheritance for 4G Sessions on Legacy Interfaces

SMF with legacy interfaces supports the DNN inheritance feature.

Default Setting: Disabled – Configuration required to enable

Dynamic ADC Rules Over Gx Interface

SMF allows the users to install, modify, or remove the dynamic ADC rules. SMF forwards the new or updated rules to UPF for traffic classification.

This feature allows the service providers to manage the IoT devices, such as connected cars, and charge their subscribers based on the traffic flows classified by SMF/UPF. With this traffic classification, the service providers enable service monetization.

Default Setting: Enabled – Always On

M6 Server Performance and Scaling

With this release, the SMF (with Legacy Interfaces) was tested and validated for 5 million sessions scale for IoT use cases using the M6 based UCS systems with published call model including Modeled CEPS and DNN/IP pool configuration.

Default Setting: Not Applicable

M7 Server Functional Qualification

With this release, the SMF (with Legacy Interfaces) was functionally qualified for IoT use cases using the M7 based UCS systems.

Default Setting: Not applicable

Troubleshooting GTP-C Services

This feature allows the cnSGW and SMF+PGW-C to send the GTPC test echo command to peer nodes to:

• Troubleshoot and monitor the connectivity of peer nodes.

• Test a Round Trip Time (RTT) of the peer.

• Supports S11, S5E, S5, S2B and S8 GTPC interfaces, and IPv4 and IPv6 transport types.

Default Setting: Enabled – Always On

Troubleshooting GTPP Services

This feature allows the SMF+PGW-C to send a GTPP test echo command to the CGF server to:

• Troubleshoot and monitor the connectivity of CGF servers.

• Test Round Trip Time (RTT) of the peer.

Default Setting: Enabled – Always On

Enhancing Local Policy Statistics for N7 Connectivity

Previous Behavior: SMF triggers the local_policy label as part of smf_service_stats to represent all the N7 connectivity event triggers.

New Behavior: To provide more granular information on the various N7 events, the local_policy label is renamed as policy_status.

The policy_status label has the following values:

• N7Skip: Specify that the PCF interaction is disabled.

• N7DisableLocalPolicy: Specify that a local policy is enabled or used.

• N7Active: Specify that the PCF provided policies are used.

Event Trace Log for SMF-initiated PDU Session Release

Previous Behavior: The error log "EVENT TRACE for RelProcType" was generated for create over create scenarios, that is, when SMF initiates the PDU session release procedure for existing session.

New Behavior: Error log "EVENT TRACE for RelProcType" is no longer added to avoid log flooding in a valid scenario of create over create.

Handling Terminate Sub Action FHT in CCA-I

Previous Behavior: SMF terminates the session without sending the Gy CCR-T whenever the Gy CCR-I has failed with FHT action Terminate and subaction WITH_TERM_REQUEST.

New Behavior: SMF terminates the session and sends the Gy CCR-T when the Gy CCR-I fails with FHT action Terminate and subaction WITH_TERM_REQUEST.

Preemptive Quota Request for Static and Predefined Rules

Previous Behavior: SMF didn’t have the capability to request for preemptive quota for during the initial attach scenario.

New Behavior: SMF can now request preemptive quota for both static and predefined rules during the initial attach procedure through a preemptively-request-n-validate CLI command in the Charging Action configuration.

Presence of Dummy Charging Information in Show Subscriber Output

Previous Behavior: SMF used to display dummy data under PolicySubData in the show subscriber output if there’s no charging data generated for both online and offline charging.

New Behavior: Dummy data is no longer part of the show subscriber output when there’s no charging data for the PCC rules.

S-NSSAI IE over N4 Interface

Previous Behavior: SMF doesn’t send S-NSSAI of PDU session to UPF.

New Behavior: SMF includes S-NSSAI IE in the PFCP Session Establishment Request message over the N4 interface. SMF sends this IE to UPF during the PDU session establishment.

Unique Charging Identifiers for Default and Dedicated Bearers in Converged Calls

Previous Behavior: SMF used to allocate the same charging ID to all the dedicated bearers for visiting LBO sessions in the 4G network. SMF forwards the same charging ID to S-GW through the Create Bearer Request message, Due to this behavior, differentiating the CDRs for the default and dedicated bearers becomes difficult.

New Behavior: SMF generates and allocates a unique charging ID to each dedicated bearer for visiting LBO sessions only when QoS flow Based Charging (QBC) charging is enabled. This unique identifier helps S-GW to easily identify the CDR records generated for default and dedicated bearers.

Validation Check Enabled for show peers Command

Previous Behavior: The show peers command used to display the peer information with duplicate entries in different table outputs.

New Behavior: It is mandatory that you specify one of the following options with a show peers command.

• all

• ipv4

• ipv6

If the show peers command is executed without any option, SMF returns a command syntax error message. Through this validation check, display of duplicate records is avoided.

Similar behavior is additionally observed with the following commands:

• show rpc

• show endpoint

• show vrf-info

Validation of Load Metric IE

Previous Behavior: SMF didn’t accept the UPF Load Metric IE with value 0 and rejected the Sx Session Report Request message with mandatory_IE_Missing cause.

New Behavior: SMF complies with 3GPP TS- 29.244, release 16 and accepts the Load Metric IE with the value 0. This action results in no rejections while processing the Sx request messages.