1. A system for monitoring a communications network, the network being made up of many components, and being arranged for carrying many flows of telecommunications traffic, having different values, the system being coupled to the components to monitor the flows in the network, and being coupled to a store of value information based on one or more service level agreements relating to at least some of the flows, the value information indicating one or both of a positive revenue from the successful operation of the flow, and a negative revenue if the flow is degraded, the system having: a flow identifier for identifying which of the monitored flows of traffic rely on a given one or more of the components, and a valuer arranged to determine a total value of the identified flows from the store of value information relating to the identified flows.