SIP Dialog Reestablishment via Replaces Header
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Solution Overview
Problem
Communication systems, particularly SIP systems, face disruptions when a network interface fails, leading to call drops, as existing technologies do not efficiently manage transitions between different network interfaces or subnets.
Innovation Solution
A method where a communication device sends a SIP INVITE with replaces header message containing a second network address, allowing the system to reestablish a communication session using the new address, ensuring continuity of the dialog and media stream even when a network interface fails or changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a communication device uses multiple network interfaces with different subnets, then the device can maintain communication paths through alternative networks, but the call is dropped when the current network interface fails
Solution Approach 1:
The system performs preliminary actions by establishing a second dialog before the first dialog fails. The communication device proactively creates an alternative SIP dialog using a different network interface while the original dialog is still active, ensuring that a backup communication path is ready before needed. This prevents call drops by having the alternative path pre-configured and validated.
Solution Approach 2:
The patent introduces an intermediary mechanism (the second SIP dialog acting as a mediator) that bridges the gap when the primary communication path fails. When the first dialog breaks, the system can transition to the second dialog, which serves as an intermediary backup path maintained through periodic REFER methods, ensuring continuous communication without direct exposure of the failure.
2Reliability
If the system establishes a backup dialog using REFER methods, then call continuity is maintained during network interface failure, but the device complexity and signaling overhead increase
Solution Approach 1:
The REFER method is used for multiple purposes: initially to create the backup dialog, and subsequently to maintain it through periodic refreshes. This multi-functional use of a single protocol mechanism reduces the need for separate specialized procedures, simplifying the overall system while maintaining reliability through automated backup dialog management.
Solution Approach 2:
The system implements self-service through automated REFER method execution. The communication device automatically manages the backup dialog lifecycle by sending periodic REFER requests to refresh the alternative path without user intervention. This self-managing approach reduces operational complexity while ensuring the backup path remains valid and ready for immediate activation.
3Ease of operation
If the system uses SIP INVITE with replaces header to reestablish dialogs, then seamless transition between network interfaces is achieved, but the signaling message complexity increases
Solution Approach 1:
The system leverages parameter changes in SIP messages, specifically the replaces header field, to enable seamless dialog transitions. By modifying the replaces header parameter to reference the alternative dialog during network interface failures, the system achieves smooth handover between network paths without requiring fundamental changes to the SIP protocol structure, thus balancing ease of operation with manageable complexity.
Data Source
AI summary
A communication session is established between a first communication device and a second communication device. The communication session comprises a first dialog between an application server and the first communication device. The first communication device uses a first network address in the first dialog. In response to an event, such as a first network interface failing, a SIP INVITE with replaces header message is received by the application server with a second address of the first communication device. In response to receiving the SIP INVITE with replaces header message from the first communication device with a second address of the first communication device, the first dialog between the application server and the first device is reestablished using the second network address.