Description
The User Plane Node Management Information Container (UMIC) is a concept and data structure defined within the 5G core network architecture, specifically related to the Packet Forwarding Control Protocol (PFCP) which is used for communication between the Control Plane Function (CPF) – such as the Session Management Function (SMF) – and the User Plane Function (UPF). The UMIC is not a standalone protocol but a container or information element that can be included within certain PFCP messages. Its primary purpose is to transport management and operational information about the state of the UPF to the controlling CPF.
Architecturally, the UMIC is generated by the UPF. It encapsulates various types of management information that reflect the UPF's current operational status. This information can include metrics related to load (e.g., CPU utilization, memory usage, packet processing rate), overload control indicators (signaling that the UPF is approaching or in an overloaded state), and other node-specific management data. The UPF includes this UMIC in PFCP messages sent to the SMF, such as in PFCP Session Modification Response messages or potentially in PFCP Association Update messages. Upon receiving a message containing a UMIC, the SMF parses the container to extract the management information.
The role of the UMIC is to provide the control plane with real-time or near-real-time visibility into the health and capacity of user plane nodes. This enables several advanced network management functions. For example, an SMF receiving a UMIC indicating high load on a particular UPF can make informed decisions for new sessions, potentially selecting a different, less-loaded UPF for session establishment (load balancing). If the UMIC signals an overload condition, the SMF can trigger overload control procedures, such as rejecting new session requests or gracefully redirecting traffic. The UMIC facilitates a closed-loop management system where the control plane can dynamically adapt its decisions based on the actual state of the user plane resources, moving beyond static configuration. This is a key enabler for network automation, elasticity, and efficient resource utilization in cloud-native 5G core networks.
Purpose & Motivation
UMIC was introduced in 5G Release 17 to address the need for enhanced and dynamic management of the disaggregated user plane. In previous architectures and early 5G releases, control plane decisions (like UPF selection) were often based on static configuration (e.g., Network Repository Function (NRF) profiles) or simple policies. There was no standardized, in-band mechanism for a UPF to proactively report its dynamic load or overload status to the SMF during active PFCP sessions. This limitation could lead to sub-optimal load distribution, where an SMF might continue assigning sessions to an overloaded UPF because it lacked real-time information.
The creation of UMIC solves this problem by defining a standardized container to carry this vital management information within the existing PFCP signaling channel. This allows for immediate and context-aware reactions from the control plane. The motivation stems from the cloud-native principles of 5G, where UPFs are expected to be software instances scaled elastically. To automate scaling and traffic steering, the control plane requires fine-grained feedback from the user plane. UMIC provides this feedback loop, enabling more intelligent load balancing, proactive overload avoidance, and improved overall network resilience and quality of service. It represents an evolution towards self-optimizing networks where the core network functions can autonomously adapt to changing load conditions.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (290 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the UMIC function was newly introduced to enable user plane reporting and event subscriptions, specifically for managing User Plane Inactivity reporting on the N4 interface and subscribing to UP Path management events with a new data type. This introduction also included enhancements for reporting access network information and adding QFIs to the Packet Detection Information. These changes provided the SMF with more detailed control and monitoring capabilities over the user plane node through the PFCP protocol.
- Update of Provisioning of charging related information for PDU session TS 29.512CR0025
- Provisioning of IP index information TS 29.512CR0027
- Missing Slice Information TS 29.512CR0051
- Correction of 404 error information TS 29.512CR0093
- The SMF may allow traffic to start before quota management for online charging TS 29.512CR0178
- Correction to credit management session failure TS 29.512CR0187
+ 22 more changes
In Release 16, the UMIC function was enhanced to support Time Sensitive Networking (TSN) and Time-Sensitive Communication (TSC) by introducing new containers for transporting TSN information and TSC Assistance Information (TSCAI) between the SMF and PCF. It also expanded to include Bridge Management Information and clarified the management information for DS-TT and NW-TT ports. Furthermore, the release added support for transporting these TSN information containers between the PCF and AF.
- Transport of TSN information and containers between SMF and PCF TS 29.512CR0368
- Transport of TSC assistance information between SMF and PCF TS 29.512CR0369
- HFC node Id in Location information, TS 29.512 TS 29.512CR0390
- Clarification of DS-TT and NW-TT ports management information TS 29.512CR0425
- TSCAI input container and TSN QoS container TS 29.512CR0427
- CHF set and instance Id in charging information TS 29.512CR0431
+ 71 more changes
In Release 17, the UMIC function was enhanced to support new PFCP Node related messages and procedures over the N4mb interface. This included enabling User Plane (In)Activity Detection and Reporting
- PMF address information per QoS flow TS 29.244CR0557
- PFCP Node related messages supported over N4mb TS 29.244CR0606
- User Plane (In)Activity Detection and Reporting over N4mb TS 29.244CR0608
- Redirect Port Information TS 29.244CR0613
- Transport Level Marking information for PFCP sessions over N4mb TS 29.244CR0622
- DL MBS QFI Sequence Number in PDU Session Container TS 29.244CR0615
+ 57 more changes
In Release 18, the UMIC function was enhanced to support new reporting and monitoring capabilities directly from the UPF, including the direct reporting of TSC Management Information and the exposure of congestion information. It also introduced extensions for specific PDU session types and updated procedures for inactivity detection and session modification with TL-Containers. Furthermore, new container formats, such as for PDU Set Information in GTP-U, were defined to carry this expanded user plane node management data.
- Direct reporting of TSC Management Information from UPF to TSN AF or TSCTSF TS 29.244CR0725
- Congestion information monitoring TS 29.244CR0724
- Reporting suggestion information for QoS flow related QoS monitoring TS 29.244CR0733
- TL-Container for the support of TSN enabled Transport Network TS 29.244CR0734
- User plane inactivity detection update TS 29.244CR0731
- Exposure of congestion information TS 29.244CR0739
+ 64 more changes
In Release 19, the UMIC function was enhanced to support the transfer of media-related information over the N6 interface using connect-UDP and UDP Option methods for end-to-end encrypted traffic. It also introduced the handling of (S)RTP Multiplexed Media Identification Information to enable more efficient media session management. Additionally, new capabilities were added for QoS notification control with direction information and for providing alternative SMFs per PFCP session to improve session resilience.
- Supported functionality of NAT information exposure TS 29.244CR0876
- PFCP sessions excluded from the restoration upon a SMF failure with SMF set being deployed TS 29.244CR0895
- Transferring media related information over N6 using connect-UDP for e2e encrypted traffic TS 29.244CR0894
- Description for handling of allowed VLAN tags and use of VLAN Handling Information in SMF TS 29.244CR0884
- Providing alternative SMF(s) per PFCP Session TS 29.244CR0911
- Leveraging PDU Set QoS information for DSCP marking over N3/N9 in the transport network TS 29.244CR0912
+ 46 more changes
Explore further
Broader topics and technologies where UMIC plays a role.
Defining Specifications
3GPP specifications that define or reference UMIC, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 29.244 vj40 | PFCP Specification for Control/User Plane Separation | Rel-19 |
| TS 29.512 vj40 | 5G Session Management Policy Control Service | Rel-19 |
| TS 29.513 vj40 | 5G PCC Signalling Flows & QoS Mapping | Rel-19 |
| TS 29.514 vj40 | 5G System; Policy Authorization Service; Stage 3 | Rel-19 |