Stray Session Request Handling in 3GPP Networks
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Solution Overview
Problem
Current methods for handling stray session requests in network environments, particularly in 3GPP networks, are inadequate, leading to overwriting of valid sessions due to delays and race conditions, resulting in call failures and resource inefficiencies.
Innovation Solution
The proposed solution involves adding a timestamp (ULI timestamp) and a retry count (GW-retry-count) to create session requests, which are then used by peer nodes like the AAA element and PCRF to identify and handle stray session requests, preventing overwriting of valid sessions through a heuristic algorithm that compares timestamps and retry counts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequence numbers are used to order binding update messages at the home agent, then message ordering is improved, but synchronization complexity between multiple entities increases
Solution Approach 1:
The patent uses the NAI (Network Access Identifier) as an intermediary to carry sequence number information. Instead of requiring direct synchronization between multiple entities (MN, PMA, HA), the sequence number is embedded in the NAI field of EAP messages, allowing indirect information transfer and eliminating the need for complex synchronization protocols between these entities.
2Measurement precision
If timestamps are compared to determine message order, then ordering accuracy is improved, but processing overhead increases
Solution Approach 1:
The sequence number is assigned in advance to each binding update message at the source (MN or PMA) before transmission. This preliminary numbering allows the HA to determine message order through simple integer comparison rather than complex timestamp processing, reducing computational overhead while maintaining ordering accuracy.
3Reliability
If guard timers are used to prevent stray session requests, then session validity is improved, but resource consumption increases
Solution Approach 1:
The patent replaces the mechanical timer-based guard mechanism with a logical sequence number comparison system. Instead of maintaining time-based state and consuming timer resources, the system uses sequence numbers embedded in messages to logically determine session validity, eliminating the need for guard timers and reducing resource consumption.
4Measurement precision
If retry counts are tracked to identify stray requests, then identification accuracy is improved, but data storage requirements increase
Solution Approach 1:
The patent merges multiple information elements (sequence number, retry count, session identifier) into existing message fields rather than creating separate storage structures. The sequence number is embedded in the NAI field, and retry counts are incorporated into existing session management data structures, achieving accurate identification without increasing overall data storage requirements.
Data Source
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AI summary
An example method is provided in one example embodiment and may include receiving a session request for a user equipment (UE) at a node, wherein the session request includes a timestamp for the UE and a retry count; determining if the session request is a stray session request; and maintaining session information for an existing session for the UE at the node if the session request is a stray session request. The method can include identifying the received session request as a stray request if the timestamp received in the request is less than a timestamp stored for an existing session for the UE. The method can also include identifying the received request as a stray request if the timestamp received is equal to the timestamp stored for the existing session and if the retry count received is less than or equal to a retry count stored for the session.