1. A service model impact propagation method, comprising: creating a data structure of a service impact model, the data structure having nodes representing components of the service impact model and having impact relationships between at least some of the nodes, each of the nodes having one of at least two states, wherein the at least two states are respectively indicative of at least two operational statuses for their respective node; associating one or more counts with at least some of the nodes, each count of the one or more counts for a given one of the nodes representing a number of the nodes having impact relationships with the given node with a respective one of the at least two states, wherein each state of the at least two states comprises one of a respective discrete operational status, a respective range of percentage availability or a respective range of throughput levels; changing a state of a first of the nodes; propagating impact of the change to counts associated with one or more second nodes having impact relationships with the first node to reflect the change of the state of the first node; and determining a state of the one or more second nodes with the counts.