PFCP Session Audit Using F-SEID Mapping for Zombie Session Cleanup
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Solution Overview
Problem
Existing communication systems face issues with zombie sessions due to lack of awareness of session status during High Availability (HA) or interface restarts, leading to processor consumption and performance degradation without defined procedures for session audit in control and user planes.
Innovation Solution
Implementing a session audit method using vendor-specific information elements (IEs) in the Packet Forwarding Control Protocol (PFCP) for exchanging CP and UP F-SEIDs to identify and clean up zombie sessions, allowing for efficient session management without disrupting existing 3GPP-defined procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If session audit is implemented to identify zombie sessions, then system reliability is improved, but device complexity increases due to additional protocol extensions
Solution Approach 1:
The vendor-specific IE is integrated into the existing PFCP association update request/response messages, allowing the same message structure to serve both existing session management and new zombie session detection functions, thereby avoiding additional protocol complexity
Solution Approach 2:
A vendor-specific information element acts as an intermediary carrier within the PFCP protocol, enabling session audit functionality without modifying the core protocol structure or requiring separate communication mechanisms
2Productivity
If session audit is performed to manage zombie sessions, then system performance is improved by reducing processor load, but loss of time occurs during the audit process
Solution Approach 1:
The session audit is triggered automatically upon detecting specific events such as HA restart or interface restart, performing the audit action in advance before zombie sessions can accumulate and impact system performance
Solution Approach 2:
The audit mechanism provides feedback by identifying zombie sessions and enabling their cleanup, creating a closed-loop system that continuously monitors and maintains session status accuracy to prevent performance degradation
3Adaptability or versatility
If CP and UP functions are separated for scalability, then adaptability is improved, but loss of information occurs during HA or interface restarts
Solution Approach 1:
The session audit mechanism establishes a feedback loop between CP and UP functions, allowing each to query and verify session status information after HA or interface restarts, ensuring information consistency across the separated functions
Solution Approach 2:
The vendor-specific IE in PFCP messages serves as an intermediary information carrier that bridges the CP and UP functions, enabling them to exchange session status information reliably even when separated in distributed deployments
Data Source
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AI summary
There is provided a method for a session audit in a communication system having a first plane and a second plane. The method can be employed in a case in which the first plane is a control plane and the second plane is a user plane, or a case in which the first plane is a user plane and the second plane is a control plane. The first plane performs operations of (1) sending to the second plane, an association update request that contains a first vendor-specific information element (IE) having (a) a bit set to indicate a desire for a single control plane (CP) fully-qualified session identification (CP F-SEID), and (b) a CP F-SEID, and (2) receiving from the second plane, an association update response that contains a second vendor-specific IE having (a) the CP F-SEID, and (b) a mapped user plane (UP) fully-qualified session identification (UP F-SEID).