Session Management Restoration Flag for IP Allocation Conflict
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Solution Overview
Problem
The existing PFCP Session Restoration procedures in 4G and 5G wireless communication networks face conflicts in F-TEID and UE IP address allocation between control plane (CP) and user plane (UP) functions during restoration and new session establishment, leading to rejection of requests and unsupported reactive restoration for PGW-U and UPF anchor failures.
Innovation Solution
Incorporating a data restoration flag and a new information element (IE) UE IP address Pool ID in session establishment requests to facilitate clear logic for F-TEID and UE IP address allocation, enabling proactive and reactive restoration methods, and allowing the control plane to select specific IP address ranges based on UE location and RAT type for UPF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the control plane allocates F-TEID and UE IP address during session restoration, then the user plane can restore sessions efficiently, but conflicts arise with new session establishment where the user plane expects to allocate these resources
Solution Approach 1:
The control plane performs preliminary actions by allocating F-TEID and UE IP address during session restoration before the user plane needs them, and includes a restoration indication flag in the session establishment request to pre-notify the user plane of the allocation mode, preventing conflicts with new session establishment
Solution Approach 2:
The patent changes the parameter allocation mode by introducing a restoration indication flag that switches the F-TEID and IP address allocation responsibility from the user plane to the control plane during restoration scenarios, while maintaining the original user plane allocation mode for new sessions
2Loss of time
If the control plane restores sessions proactively immediately after user plane restart, then service recovery time is reduced, but the system complexity increases due to need to track and restore all sessions
Solution Approach 1:
The control plane performs preliminary action by proactively restoring all sessions immediately after user plane restart is detected through heartbeat messages, rather than waiting for reactive triggers, thereby reducing service recovery time
Solution Approach 2:
The system uses feedback mechanisms where the user plane sends heartbeat messages containing recovery time stamps to the control plane, which automatically triggers the proactive restoration process, reducing the need for complex manual tracking
3Adaptability or versatility
If the control plane uses wildcarded PDR to forward unknown packets during reactive restoration, then all packets can be routed to control plane for processing, but the user plane cannot determine the responsible control plane function for specific UE IP addresses
Solution Approach 1:
The patent introduces an intermediary mechanism where the control plane maintains a mapping between UE IP addresses and responsible CP function identifiers, allowing the user plane to forward packets with wildcarded PDR to a default CP while the intermediary mapping enables accurate identification of the responsible CP function for each UE
Data Source
AI summary
A method and apparatus for session management. The method at a control plane function comprises determining data to be restored in a user plane function or a first Internet Protocol (IP) address pool identifier. The method further comprises sending a first session establishment request to the user plane function, wherein the first session establishment request includes a data restoration flag and the data to be restored in the user plane function or includes the first Internet Protocol address pool identifier. The first Internet Protocol address pool identifier is used by the user plane function to assign an IP address to a user equipment from the first Internet Protocol address pool identifier.