Connection establishment in time critical scenarios

In a scenario where service reliability is achieved through multiple providers, it is crucial to detect faulty equipment. Such a scenario is the IP Multimedia Core Network Subsystem (IMS). where service is provided by multiple instances of the Application Server (AS). These servers may reside on remote locations, and network link between the Call Session Control Function (CSCF) and AS may become broken or overloaded. In these cases the IMS infrastructure relies on the SIP and IP protocols to detect the failures, and lets the CSCF try to connect to the next available AS. However the elapsed time until the successful connection can be enormous and unacceptable for the users. In this paper we describe a non-intrusive solution, which could circumvent the delay problems without requiring any modifications of existing standards and implementations.