In terms of structure, the System X processor is a "one master, many slaves" configuration – cluster 0 is referred to as the base cluster and all other clusters are effectively dependent to it. If a slave cluster is lost, then call handling for any routes or concentrators dependent to it is also lost; however, if the base cluster is lost then the entire exchange ceases to function. This is a very rare occurrence, as due to the design of System X it will isolate problematic hardware and raise a fault report. During normal operation, the highest level of disruption is likely to be a base cluster restart, all exchange functions are lost for 2–5 minutes while the base cluster and its slaves come back online, but afterwards the exchange will continue to function with the defective hardware isolated.