Logical Scalable Units for VoLTE Session Continuity
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Solution Overview
Problem
Current telecommunications networks face challenges in scaling stateful application servers, such as policy and charging application servers, which require high availability and redundancy, making it difficult to implement seamless scaling using existing scalable computing resources.
Innovation Solution
The implementation of Logical Scalable Units (LSUs) with a processor-executable method that manages session continuity information, allowing for the continuation of VoLTE sessions even if a datacenter fails, by using common keys to identify application components and update cache memory, ensuring session continuity and redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stateful application servers are deployed to ensure high availability and redundancy, then reliability is improved, but scalability is worsened because existing scalable computing resources cannot support linear scaling of stateful servers
Solution Approach 1:
The patent divides the stateful application server into multiple independent stateful application servers that can be scaled horizontally. Each server maintains its own session store, allowing independent scaling without affecting others. This segmentation enables the system to achieve both high availability through redundancy and scalability by adding or removing individual server instances based on demand.
Solution Approach 2:
The patent implements copying of session continuity information between datacenters. When a datacenter fails, session continuity information is copied to another datacenter to maintain service continuity. This copying mechanism enables high availability while allowing the system to scale by replicating functionality across multiple datacenters.
2Speed
If session continuity information is maintained in cache memory for VoLTE session continuation, then responsiveness is improved, but device complexity increases due to the need for managing common keys and cache updates
Solution Approach 1:
The patent uses a common key mechanism that serves multiple functions: identifying application components, retrieving session continuity information from cache memory, and updating cache entries. This universal approach to key management simplifies the system by consolidating multiple operations into a single mechanism, reducing the complexity that would otherwise arise from managing separate identification and caching systems.
3Reliability
If multiple datacenters are deployed for redundancy, then reliability is improved, but loss of time increases during failover events when session continuity must be maintained
Solution Approach 1:
The patent implements preliminary copying of session continuity information to backup datacenters before failures occur. By maintaining updated session continuity information in cache memory across multiple datacenters in advance, the system can failover quickly when a datacenter fails, minimizing the time loss that would otherwise occur during the transition.
Data Source
AI summary
Logical scalable units (LSU) can be used within a single network data center to provide stateful scalability. However, LSUs are not suitable for operating across multiple network data centers in order to provide geographical redundancy in active-active scenarios while providing high availability. This is because the latencies associated with replicating full session information are unacceptably slow. An additional component in the LSU (known as an LSU Frontend) can be used to replicate a small subset of session information between LSUs. This subset of session information may be enough to enable LSUs to process requests in an acceptable way rather than outright failing. This may be particularly advantageous in scenarios where the requests relate to Voice over LTE calls, because outright failure is very perceivable to subscribers, and it causes resource leakage within the telecommunications network.