SMF

Configuration-based Control of Subscription Notification with Immediate Report Indication on N10 Interface

With the "immediateReport" attribute enabled on UDM, the SMF ignores the UDM subscription fetch message and continues with the Subscription Notification Request, in which Subscription Management Data is received in the Subscription Notification Response.

With this controlled UDM notification subscription with the immediate report indication, the interactions between SMF and UDM over the N10 interface are minimized during the 4G, 5G, and Wi-Fi attach procedures and hence prevents message overload and failures.

This feature introduces the new CLI command subscription notify-immediate in the DNN profile.

Default Setting: Disabled – Configuration Required

Event Failure Logs for Release procedure

With this feature, the consistent event failure logs are enhanced to support the Release procedure for SMF, 4G, and hSMF interfaces.

Default Setting: Not Applicable

N3IWF Enhancement

Following are the additional enhancements to the N3IWF for the seamless communication between the Wi-Fi network and the cellular network.

• UE-initiated Service Request through N3IWF

• Wi-Fi to NR Handover (HO) through N3IWF

• NR to N3IWF Wi-Fi HO

• UE-initiated idle mode entry and exit procedure

• Voice or Video Call Over Wi-Fi with N3IWF and HO support with Active Bearer. SMF also supports Evolved Packet System (EPS) fallback during handover.

• Handling of RAT Type for N3IWF Sessions

UCS C220 M7 Server Qualification

In this release, SMF is functionally qualified on the Cisco UCS C220 M7 server.

The Cisco UCS C220 M7 Rack Server is a versatile general-purpose infrastructure and application server. This high-density, 1RU, 2-socket rack server delivers industry-leading performance and efficiency for a wide range of workloads, including virtualization and bare-metal applications.

UE IP Address Hold and Reuse Functionality

This feature allows SMF to allocate the same IP address and session ID to a user session if the user reattaches within a configurable session hold timer after session release.

This improves the user experience and reduces the IP address exhaustion in scenarios where users frequently attach and detach.

Command introduced: session-hold duration in Converged Core profile and DNN profile configurations.

Default Setting: Disabled – Configuration Required

Mobile IoT

Indication for UPF-initiated PFCP Association Release

This feature enables SMF to receive notification on UPF-initiated PFCP Association Release procedure. This notification indicates to clear the sessions and association simultaneously in UPF and SMF.

If the SMF is not notified, the call remains connected until UPF receives the next Session Modify Request from the SMF. This leads to loss of subscriber usage reports. Here, the Enhanced PFCP Association Release (EPFAR) feature improves the signalling efficiency and effective handling of usage reports by SMF.

Default Setting: Disabled – Configuration Required to Enable

Modification of QCI, ARP, and Online/Offline Charging Attributes

With this release, SMF supports modification of these additional AVPs included in the dynamic ADC rule:

• QCI

• ARP

• Online

• Offline

These modifications allow the service providers to classify the traffic more efficiently.

Rolling Upgrade Optimization for Endpoint Pods

SMF provides the rolling upgrade optimization support for the following pods:

• RADIUS endpoint pod

• Diameter endpoint pod

• UDP proxy pod

• GTPP endpoint pod

This optimization is an enhancement to the existing optimization.

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

UCS C220 M6 Server Performance and Scalability

With this release, the SMF (with Legacy Interfaces) was tested and validated for 7 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.

To improve the scalability, SMF also provides new configuration options at GR instance level to

• enable sharding on IPAM cache data using the CLI command data-sharding num-shards ipam_data_shards .

• disable chunk throttling using the CLI command chunk-throttling false .

AVP Validation for Call Processing in Gx and Gy Endpoints

Previous Behavior: SMF did not validate the presence and values of the mandatory AVPs used for call processing.

New Behavior: SMF verifies that the mandatory base AVPs are present and have valid values for the AVPs. If the validation fails, SMF informs service with action as terminate and sub-action as with-term-req for both Gx and Gy.

Change in RAT Type Validation for N3IWF Sessions

Previous Behavior: SMF used to process the PDU session establishment request received for N3IWF-based sessions with RAT type set to NR.

New Behavior: SMF now rejects PDU session establishment requests for N3IWF-based sessions with RAT type set to NR. SMF processes the requests only if the RAT type is set to WLAN.

Customer Impact: You might observe call failure due to the rejection of PDU session establishment request for N3IWF sessions with NR RAT type.

Changes to Naming of usedUnitContainer Attribute on N40

Previous Behavior: The attribute "usedUnitContainer" was sent with upper case "UsedUnitContainer" when 3GPP release 16 (16.8.1) version was configured for N40 interface on SMF.

New Behavior: The case of the usedUnitContainer attribute on N40 interface changes when 3GPP release 16 is activated at SMF. It becomes lowercase "usedUnitContainer" instead of uppercase "UsedUnitContainer".

Customer Impact: For each 3GPP release version, handle N40 messages based on the case change.

Generate Pod Logs in JSON Format

Previous Behavior: SMF did not have functionality to generate pod logs in JSON format. However, this functionality was present in the CDL application.

New Behavior: SMF can now generate pod logs in JSON format using the logging json-logging [ application | monitor-subscriber | transaction ] CLI command. Once this feature is activated, all SMF-related application pods begin generating logs in JSON for the selected log types.

Managing 3gpp-Sbi-Discovery-service-names IE in SCP Header

Previous Behavior: SMF does not send 3gpp-Sbi-Discovery-service-names IE in the SCP header.

New Behavior: SMF lets you manage the inclusion of 3gpp-Sbi-Discovery-service-names IE in the SCP header. This IE can be made conditional by using a new CLI command discovery-params [ service-names ] in SCP network element profile.

Customer Impact: If you are downgrading SMF, make sure you first disable this CLI configuration. If this CLI command is configured after the upgrade, you will observe that only the new sessions will include the discovery service names as one of the headers in SCP.

N10 Registration during Wi-Fi to 5G Handover

Previous Behavior: N10 registration did not occur during Wi-Fi to 5G handover.

New Behavior: If UDM registration was skipped during Wi-Fi attach, SMF tries to register with UDM again during Wi-Fi to 5G handover.

Note that this behavior change is observed from 2024.02 release.

NF Discovery through SUPI Query Parameter

Previous Behavior: SMF didn't have the capability to discover the peer NFs based on the SUPI query parameter.

New Behavior: SMF allows you to additionally configure SUPI as the query parameter to discover the peer NF profile.

Use the query-params CLI command in the respective NF client profile configuration mode. For more information on the command, see the UCC 5G SMF CLI Command Reference.

PDRs in N4 Modification Request during Dedicated Bearer Deletion

When inter-plmn-ho configuration is enabled for a user with VoWi-Fi call and dedicated flow, the Wi-Fi to NR handover begins. If a flow failure is observed during this handover, SMF performs the EPS fallback and subsequently removes the Packet Detection Rules (PDRs) for the failed flows.

Previous Behavior: In this scenario, when a peer NF triggers dedicated bearer deletion after EPS fallback, SMF sends the previously deleted PDRs in the N4 modification request.

New Behavior: When the peer NF triggers dedicated bearer deletion, SMF no longer sends the deleted PDRs in the N4 modification request.

Quota Management for Online URRs in CCA Messages

Previous Behavior: SMF used to send the maximum quota to UPF for all online URRs if FHT with CONTINUE action and NONE/UNKNOWN sub-action was received in CCA-I message.

New Behavior: SMF now relays the maximum quota for online URRs only when FHT with action CONTINUE and Sub-action NONE/UNKNOWN is received in Gy CCA-U.

SMF disables the Gy online charging for the session if the corresponding FHT action is set to CONTINUE in Gy CCA-I.

Retransmission of Create Session Request Response

Previous Behavior: If the SMF received the retransmitted Create Session Request before the Create Session Response, then SMF dropped the retransmitted request.

New Behavior: With the rolling updates, the Create Session Response to the retransmitted Create Session Request is sent only if the SMF receives the Create Session Request before the Create Session Response.

Roaming-status Configuration and Inter-PLMN Roaming Handovers

Previous Behavior: Inter-PLMN roaming handovers were successful even if roaming-status was configured in operator policy.

New Behavior: The inter-PLMN roaming handovers may not work as expected if roaming-status is specified in the operator policy.

PLMNs decide the roaming status. Use the roaming-status configuration to override the status determined by PLMNs only in rare situations.

Customer Impact: The success rate of inter-PLMN roaming call flows may be affected by the roaming-status configuration.

SMF Disconnect Reason Statistics for Invalid Release Requests

Previous Behavior: Disconnect reason statistics (smf_disconnect_stats) were pegged even when network- or UE-initiated release request has failed for the sessions which were not present or in different RAT type.

New Behavior: When the release requests fail with either session not exist or session in different RAT type, the SMF disconnect reason statistics do not increase.

UE Location Validation for Idle Mode Entry and Exit Procedures

Previous Behavior: SMF does not validate the UE location against the received RAT type or the RAT type available in SMF as part of PDU session context.

New Behavior: SMF validates the UE location against the received RAT type or the RAT type in the PDU session context. SMF rejects the Idle Mode (IM) procedure if there is a mismatch during the validation.

Updated "show subscriber" CLI Output for Full Database Record Update

Previous Behavior: Any change to the subscriber parameters resulted in full db record update. The show subscriber CLI command displayed old parameter values as the flagdb record was not reset.

New Behavior: Whenever the subscriber parameters change and the full db record gets updated, the show subscriber CLI shows the updated parameter values as the flag db record is reset now.

Updated Gaumi IE Encoding as per 3GPP Release 16.0

Previous Behavior: The plmnId within the Guami IE was encoded wrongly on the N7 interface. The incorrect Guami encoding caused the interoperability issue.

New Behavior: The plmnId is correctly encoded as plmnIdNid type. Now, the Guami encoding is corrected to resolve the interoperability issue and complies with the 3GPP Release 16 and above specifications.

Validation of APN String in 4G Attach Requests

Previous Behavior: For 4G attach requests received at cnSGWc, SMF, or cnPGWc, there was no validation being done for the allowed characters in the APN string.

New Behavior: SMF validates the APN string included in the 4G attach requests. If the APN string contains any characters other than ASCII printable characters (33-126), the attach request gets rejected with a cause "Missing or unknown APN (78)".

V-SMF Update Response for the H-SMF-initiated PDU Modification Procedure

Previous Behavior: For the H-SMF-initiated PDU Modification procedure, V-SMF sent the N1 N2 Transfer Request to AMF. In the N1 N2 Transfer Response timeout, V-SMF used to send the Update Response to H-SMF.

New Behavior: For the H-SMF-initiated PDU Modification procedure, V-SMF sends the N1 N2 Transfer Request to AMF. In case of the N1 N2 Transfer Response timeout, V-SMF sends the Update Failure Response with the "PeerNotResponding" cause and "HTTP_STATUS_CODE_504_GATEWAY_TIMEOUT" cause code to H-SMF.