CosMos: Building A Network Reliability Cost Modeling System for Customer SLA

Coping with the recent network system virtualization, softwareization, and federation, the network system operation and management domain becomes fiercely complex. However, as the network reliability management still practices traditional availability measures using Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR), a time-based availability contract such as network Service Level Agreement (SLA) is hard to use or enforce in the real world. The network outage measurement is an integral part of ensuring SLA conformance. However, when there is an outage, the current simple time-based SLA becomes overambitious for the customers to interpret the practical service impact due to the lack of suitable measurement tools and models. This paper proposes a novel network reliability cost modeling system (CosMos) to ensure that the SLA covers customer service impact and damage. We classify network outages and calculate their effect on the network services to formulate a cost-based model. Then we use the Markov chain to capture the redundancy switchover and network outage rippling effect details when calculating downtime. We design and develop a reliability cost modeling tool for IP-based networking systems using a user-friendly Excel tool. Besides, we have performed evaluations using various campus network outage scenarios. The proposed cost-based model enables customers to identify the service impact of unplanned network outages to their networks instead of entirely depending on the service provider's data.