SIP Fast Switchover via Subscription Notification
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Solution Overview
Problem
The transition from an active SIP host to a standby SIP host in telecommunications systems results in significant network overhead and call loss due to the need for individual messaging to update thousands of SIP dialogs, leading to inefficiencies and dropped calls during switchover events.
Innovation Solution
Implementing a subscription-based SIP fast switchover mechanism where a SIP entity receives a SUBSCRIBE message for fast switchover notification, allowing the standby host to switch to active mode and send a NOTIFY message to associate SIP dialogs with the new active host, reducing the need for individual messaging and minimizing network traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual messaging is used to update each SIP dialog during switchover, then all dialogs can be properly associated with the new active host, but network overhead and message traffic increase significantly
Solution Approach 1:
The patent merges thousands of individual dialog update messages into a single system-wide notification message. When a standby SIP host becomes active, instead of sending individual INVITE/ACK message sequences to each peer entity for every dialog, the system sends one NOTIFY message to all subscribed peer entities, which then update all their dialogs simultaneously. This combining approach maintains complete dialog association accuracy while reducing network message volume from thousands of messages to just one.
Solution Approach 2:
The patent segments the switchover notification process into two distinct parts: (1) the SIP host switchover event itself, and (2) the dialog update notification distributed to peer entities. By separating the trigger event from the individual dialog update actions, the system can notify all peers of the switchover event once, allowing each peer to independently update all its dialogs without requiring coordinated individual messaging for each dialog, thus reducing overall network overhead.
2Reliability
If individual messaging sequences are sent for each dialog during switchover, then proper dialog association is achieved, but switchover time increases causing call loss
Solution Approach 1:
The patent combines thousands of sequential dialog update operations into a single parallel notification event. By sending one NOTIFY message to all subscribed peer entities simultaneously, the system enables all dialogs across all peers to be updated in parallel rather than sequentially. This reduces switchover time from potentially minutes (with individual messaging) to seconds or less, while maintaining complete dialog association accuracy through the structured notification process.
Solution Approach 2:
The patent implements preliminary subscription setup where peer entities subscribe to switchover notification services before any switchover event occurs. This preliminary action ensures that when a switchover happens, all peers are already registered and ready to receive notifications immediately, eliminating any setup delay during the actual switchover. The pre-configured subscription mechanism allows the system to execute the notification and dialog update process as quickly as possible, minimizing switchover time while ensuring no dialog association errors occur.
3Reliability
If periodic updates are sent from active to standby host, then standby host is maintained in ready state, but network overhead increases
Solution Approach 1:
The patent implements periodic subscription-based updates where the active SIP host sends LOAD_UPDATE messages to the standby host at regular intervals (e.g., every 5 seconds). This periodic action maintains the standby host in a ready state with current load information without requiring continuous messaging. The standby host uses this periodic information to prepare for potential switchover, ensuring reliability while keeping network overhead manageable through the structured periodic update mechanism rather than continuous or event-driven messaging for each dialog.
Data Source
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AI summary
Disclosed are methods, systems, and computer program products for notifying a Session Initiation Protocol (SIP) entity of a fast switchover event. According to one method a first SIP entity having an active host and a standby host is provided. At the active host a SUBSCRIBE message is received from a second SIP entity for subscribing to a fast switchover notification service. The standby host is switched to an active mode. In response to switching the standby host to active mode, a NOTIFY message is sent to the second SIP entity for notifying the second SIP entity that the standby host is operating in active mode.