SMF-UPF IP Pool Reclamation Using Session Floor Thresholds
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Solution Overview
Problem
In Fifth Generation (5G) core networks, inactive sessions linger on user plane functions (UPFs), leading to under-utilization of IP pools, which results in inefficient allocation and over-allocation by the Session Management Function (SMF) due to the under-utilization of IP pools, causing a shortage of available IP pools.
Innovation Solution
Implementing a floor threshold mechanism in UPFs and SMF to detect when session counts fall below a predefined threshold, triggering the release of remaining sessions and reclaiming the IP pool, with the SMF reallocating resources based on session reports and delete cause codes to manage IP usage, and re-allocate IP addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SMF allocates IP pools to UPFs based on session reports indicating zero sessions, then IP pools are reclaimed when truly unused, but inactive sessions linger and prevent reclamation causing under-utilization
Solution Approach 1:
The patent introduces a floor threshold parameter (e.g., 3 sessions) that changes the reclamation criterion from zero sessions to a small non-zero value. This parameter modification allows the system to distinguish between truly unused IP pools and those with lingering inactive sessions, enabling more accurate reclamation decisions while maintaining efficient utilization.
2Ease of operation
If the SMF waits for zero sessions before reclaiming IP pools, then reclamation is simple based on session reports, but IP pools remain allocated to inactive sessions causing shortage of available pools
Solution Approach 1:
By changing the reclamation threshold from zero to a floor value (e.g., 3 sessions), the system proactively reclaims IP pools before they become completely idle. This maintains a simpler automated process while increasing the quantity of available IP pools for active sessions.
Solution Approach 2:
The floor threshold mechanism performs preliminary reclamation action before IP pools become completely unused. By triggering reclamation when sessions fall to the floor threshold rather than waiting for zero, the system proactively frees up resources while maintaining operational simplicity.
3Reliability
If the SMF over-allocates IP pools to ensure availability, then IP pool shortages are prevented, but UPFs hold onto under-utilized pools reducing overall efficiency
Solution Approach 1:
The floor threshold parameter creates a buffer that allows UPFs to maintain a small number of sessions (e.g., 3) without triggering reclamation. This ensures IP pool availability for near-future needs while preventing long-term under-utilization, balancing reliability and efficiency.
Data Source
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AI summary
Described herein are a session management function (SMF) and user plane function (UPF) configured allocate and utilize Internet Protocol (IP) pools to support sessions for user equipment (UE). The SMF allocates an IP pool that is then used for sessions by a UPF. The UPF determines when the count of sessions falls to a floor threshold and notifies the SMF of this. In response, the SMF sends an instruction to the UPF to release remaining sessions of the IP pool. The UPF receives the instruction and releases the sessions, and the SMF reclaims the IP pool.