Network Gateway Gx Session Backup for PCF Failure
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Solution Overview
Problem
In telecommunication networks, communication sessions fail when the Policy Control Function (PCF) is offline or the Gx interface is broken, leading to unreliable communication, especially for emergency calls, as conventional systems lack a reliable backup mechanism.
Innovation Solution
Implementing a system that detects early Gx session failures with a primary PCF and establishes a Gx session with a backup PCF of a different network generation, ensuring continuous communication session setup without relying on circuit-switched fallback procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary PCF is used for Gx session management, then communication sessions can be established normally, but the system lacks reliability when the primary PCF is offline or the Gx interface is broken
Solution Approach 1:
The gateway pre-establishes a backup Gx session with a standby PCF before the primary PCF fails. This preliminary action ensures that when the primary PCF becomes unavailable, the gateway can immediately switch to the backup session without interruption to communication sessions, thereby improving reliability while maintaining manageable complexity through proactive preparation
Solution Approach 2:
The gateway acts as an intermediary that monitors the health of the primary Gx session and automatically switches to the backup PCF when failure is detected. This intermediary function isolates the failure impact and provides a seamless transition mechanism, resolving the contradiction by adding controlled complexity at the gateway level to protect the overall system reliability
2Reliability
If early Gx session failure detection is implemented, then communication sessions can be maintained through backup PCF, but the system complexity increases
Solution Approach 1:
The gateway implements a feedback mechanism that continuously monitors the Gx session status with the primary PCF. When failure indicators are detected (such as missing CCR/CCA messages or abnormal session states), the gateway automatically triggers a switch to the backup PCF. This feedback-based approach provides reliable automatic failure detection and recovery without requiring complex manual intervention systems
Solution Approach 2:
The gateway performs self-service by autonomously detecting Gx session failures and switching to the backup PCF without external intervention. The system monitors its own session health and executes recovery actions independently, which improves reliability through rapid automatic response while keeping the complexity contained within the gateway's existing control plane functions
Data Source
AI summary
A network gateway can prevent a new communication session for a user equipment (UE) from failing by establishing Diameter Gx session binding with a backup Policy Control Function (PCF) when a Gx session cannot be established between the gateway and a primary PCF. The gateway and the primary PCF may be associated with the same network generation (such as LTE or 5G), and the backup PCF can be associated with a different network generation. An IP Multimedia Subsystem (IMS) can determine that Gx binding information about the UE is not available at the primary PCF. However, to prevent failure of the new communication session for the UE, the IMS can cause the backup PCF to use its Gx binding information to identify the Gx session established with the network gateway for the UE and provide the network gateway with rules for the new communication session.