Reliability and availability modelling of telecommunication servers on cloud

Reliability and availability considerations are discussed in this paper with special focus on `cloud based' Mobile Switching and Application Servers (MSS and AS). Before the extensive deployment of cloud based telecom networks an essential question shall be answered: Will cloud technology ensure the `carrier grade' requirements that are well established and proven on `legacy telecommunications' hardware? This paper shows the possible redundancy principles and a simulation method to predict availability for `cloudified' mobile communication network elements. As a calculation example, Nokia AS on `telco-cloud' is presented, that combines several redundancy principles such as full protection (2N), load sharing and standby.