SIP Server Multiple Identifiers for Fast Session Restoration
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Solution Overview
Problem
Current Internet Protocol Multimedia Subsystem (IMS) networks experience significant downtime and service disruptions due to the 10 to 30 second timeout period when a Session Initiation Protocol (SIP) server fails, leading to delayed session restoration and adverse consequences such as missed ring tones or lost registrations during voice over LTE calls.
Innovation Solution
Implementing multiple identifiers for SIP servers within the IMS network, where a first identifier is stored at the Home Subscriber Server (HSS) and a second identifier is inserted into SIP message headers, allowing for immediate session restoration by querying a traffic distribution server upon server failure, which returns a NULL response and triggers re-registration to a different available server.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a single identifier is used for SIP server routing, then the system structure is simple, but session restoration time is long (10-30 seconds) when server fails
Solution Approach 1:
The patent segments the identifier system into two distinct parts: a first identifier (IP address) for initial server selection and a second identifier (persistent identifier) for rapid failure detection and restoration. This segmentation allows the system to maintain simplicity in initial routing while enabling fast restoration through the second identifier mechanism.
Solution Approach 2:
The patent implements preliminary action by pre-configuring the second identifier (persistent identifier) in the HSS database before server failures occur. When a failure happens, the system can immediately query this pre-stored identifier to detect failure and initiate restoration, eliminating the need for time-consuming timeout-based detection.
2Reliability
If timeout-based failure detection is used, then the system is easy to implement, but service continuity is disrupted during the timeout period
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously queries the traffic distribution server using the second identifier to obtain real-time status information about the SIP server. This active feedback loop replaces passive timeout-based detection, providing immediate notification of server failures and enabling continuous service operation.
Solution Approach 2:
The system performs preliminary configuration of the second identifier in the HSS database, enabling immediate failure detection through query-based status checking. This preliminary setup allows the system to proactively detect failures rather than reactively waiting for timeouts, maintaining service continuity.
3Productivity
If multiple identifiers are implemented for rapid failure detection, then session restoration speed improves, but system complexity increases
Solution Approach 1:
The patent divides the identifier management into two functional components: first identifier for initial connection and second identifier for failure detection. This segmentation enables rapid restoration (milliseconds vs. seconds) while containing complexity in specific modules like the HSS database and traffic distribution server, rather than system-wide complexity.
Solution Approach 2:
The patent introduces the traffic distribution server as an intermediary that manages the second identifier and provides failure status information. This intermediary handles the complexity of identifier management and failure detection, allowing the core SIP system to maintain simplicity while achieving rapid restoration through the mediator's query-based status checking.
Data Source
AI summary
A Session Initiation Protocol (SIP) server within an Internet Protocol Multimedia Subsystem (IMS) network may be associated with multiple, different identifiers. In some embodiments, a process for implementing the multiple, different identifiers of the SIP server within the IMS network may include maintaining, at a home subscriber server (HSS), a first identifier of a Session Initiation Protocol (SIP) server in association with a user, and inserting a second identifier of the SIP server in a message header of a SIP request during a wireless communication session of the user. In some embodiments, the first identifier of the SIP server may be transmitted over Diameter (Cx) interfaces, while the second identifier of the SIP server may be transmitted over SIP (ISC) interfaces. Using multiple identifiers of a SIP server allows for minimizing downtime while restoring the user's wireless communication session in the event of a failure of the SIP server.