To analyse a cluster the two factors Frequency and Impact must be assessed. This is done in a similar way as for single failures (see Analyse the vulnerabilities of components).
In this stage, the factor Frequency reflects the likelihood that two or more components in that cluster are affected by the failure scenario. It is not required that all components in the cluster are affected. An impact class applies if the failure scenario affects one or more telecom services. For example: when the simultaneous failure of three components in a cluster would cause long-term unavailability of one telecom service, then the impact class High should be assigned to that cluster.
The Raster tool will automatically compute the vulnerability level of any parent clusters, including the top level vulnerability.