The Quality of Service Management in a Critical IT Infrastructure

any state infrastructure nowadays can’t survive without information and communication technologies. These technologies have introduced new commodities to infrastructures around the countries which caused emergence of IT infrastructures. Depending on the are of impact there are two kinds of IT infrastructures, which are critical and non-critical. Critical IT infrastructures implies bigger interest to research due to their connection with services which are here to maintain people lives, health, wealth and everyday life. As the result, it is crucial to maintain working state of critical IT infrastructures (CITI), because they are very sensitive to breaches and hazards. Breach in at least one node in CITI affects interconnected services and causes cascade fails. Among most widespread hazards for IT infrastructure is denial of service (DoS) attack. This paper introduces a way of handling quality of services in critical IT infrastructures with taking into account specific type of DoS attack which is distributed DoS (DDoS). Proposed solution is based on reliability theory and use garbage collector approach in order to control number of redundant instances which are reserved for cases of breaches.