Modeling soft state protocols with SDL

Soft state provides new services to packet-switching networks by introducing a type of state in the network nodes which is refreshed by periodical messages and otherwise expires. The operations of soft state protocols, which are being designed with ever greater complexity, need to be error-free and deadlock-free to avoid misusing network resources. Thus, verification, formal analysis and validation of these protocols become a vital task. In this paper we utilize formal techniques, specifically, Specification and Description Language (SDL) and Message Sequence Charts (MSCs), for modeling, analysis and validation of various soft state protocols. We propose a general architecture for state management systems and find employing these techniques can help identify and correct possible design errors, which may be caused by informal specifications.