Study of IMS restoration procedures
The present document identifies the changes required in the 3GPP IMS specifications so that a consistent state is restored in the IMS Core Network, after, or during a planned, or unplanned stop of a network element. The study will go through the following steps:
• Establish the requirements that should be covered with these procedures. That is which are the impacts to the end user service that are acceptable and which are not, after a network failure.
• List the service interruption scenarios that need to be studied.
• Provide solutions, so that in all the service interruption scenarios listed, the impacts to the end user service comply with the requirements. These solutions provide procedures for the automatic restoration to a consistent state in the network and indicate how to trigger these procedures.
• Analyze the impacts of the solutions in the current specifications.
• Conclusion and recommended way forward.
It is important to realise that these procedures are meant to be operational procedures for restoration and so care must be taken with what is existing and will exist with OA&M procedures to avoid overlap which could cause clashes.