PCRF Orphan Session Detection via Fake Audit Parameters
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Solution Overview
Problem
In Diameter networks, orphan sessions are not effectively detected, leading to wasted resources due to the lack of defined procedures for identifying terminated sessions, and using existing messages for auditing can trigger undesirable updates, wasting further resources.
Innovation Solution
Generating and sending Diameter audit messages with fake parameter values to detect orphan sessions on Sy and Rx interfaces, allowing the Policy and Charging Rules Function (PCRF) to determine whether a session is orphaned without triggering subscriptions or updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If existing Diameter messages are used to audit sessions, then session detection capability is improved, but resource consumption increases due to triggered subscriptions and updates
Solution Approach 1:
The patent modifies the audit message by changing the Policy-Counter-Identifier parameter from a valid identifier to a fake/invalid one. This parameter change allows the message to be processed as an audit request without triggering the subscription mechanism that would occur with a valid identifier, thus detecting orphan sessions without the associated resource overhead of policy counter updates
Solution Approach 2:
The fake parameter value acts as an intermediary mechanism that enables session detection without directly triggering the update subscription chain. By using this intermediary approach, the system can audit sessions through the existing message format while avoiding the harmful side effect of resource-intensive updates
2Difficulty of detecting and measuring
If valid policy counter identifiers are used in audit messages, then session auditing is enabled, but unwanted policy counter updates and subscriptions are triggered
Solution Approach 1:
The patent changes the Policy-Counter-Identifier parameter from valid to invalid/fake values in audit messages. This parameter modification allows the audit function to proceed while preventing the triggering of policy counter update subscriptions, thereby eliminating the harmful side effect without sacrificing detection capability
3Reliability
If keepalive timers are used to test Diameter communication availability, then communication status is monitored, but individual orphan session detection is not achieved
Solution Approach 1:
The patent segments the communication monitoring function into individual session-level audits rather than bulk communication tests. By sending targeted audit messages with fake parameters for each specific session, the system achieves precise individual session detection while maintaining the reliability benefits of active monitoring
Data Source
AI summary
A policy and charging rules function (PCRF), generates a Diameter audit message concerning an application level Diameter session for which local resources are maintained by the PCRF. The PCRF includes, in the audit message, a fake parameter value. The PCRF sends the audit message with the fake parameter value to the OCS or the AF over an Sy or Rx interface. The PCRF receives a response to the audit message from the OCS or AF. The PCRF determines, based on the response, whether the application level session comprises and orphan session. The PCRF, in response to determining that the application level Diameter session comprises an orphan session frees the local resources maintained by the PCRF for the orphan session.