Performability Management of Softwarized IP Multimedia Subsystem

IP Multimedia Subsystem (IMS) represents a crucial element for the convergence of telecommunication systems heading towards 5G solutions. Actually, IMS offers a standardized and vendor independent model allowing network providers to supply multimedia services such as video streaming or HD voice, with pressing QoS requirements. The IMS architecture can dramatically improve its flexibility when deployed within softwarized environments, in conjunction with virtual or container-based technologies. This latter, in particular, realizes an abstraction of software resources from the underlying hardware in a more efficient and resource saving manner than virtual machines. Inspired by this model, we propose a tool for the performability management of IMS architectures deployed in a containerized environment (dubbed cIMS). First, we model the stochastic behavior of a cIMS by means of two complementary formalisms: i) Reliability Block Diagram (RBD) amenable to model high level interconnections among cIMS nodes, and ii) Stochastic Reward Networks (SRN) useful to capture deeper details of a single node in terms of failure and repair events. Then, we develop an automated procedure aimed at supporting the performability management of cIMS deployments that must satisfy the optimal trade-off among high availability requirements, capacity load, and deployment costs.