f an equipment particular card. The firmware that is part of the TMN essentially performs two operations: generates alarm seeds and operates the card configuration. To exploit the first function, the firmware reads the measurements that the physical sen- sors present on the card do to assess the performance of the various hardware parts of the card and compare it with thresholds. Usually, two thresholds are set. One to separate the working within specifications from the working out of specifications, the second to sepa- rate working from not working. When one of the sensors goes beyond a threshold, the firmware produces an alarm seed that is transmitted to the agent in the control unit of the network element. In the example with two thresholds, the first threshold produces simple alarms and the second critical alarms. To perform the second function, the firmware receives from the agent configuration instructions and implements them on the card hardware. The agent is the software performing the management of the single network element as a whole. It receives from the upper layer the configuration instructions for the network element, declines them in configuration changes for the individual cards and sends com- mands to the firmware of the cards involved in the equipment reconfiguration. Telecommunication Networks Moreover, the agent receives alarm seeds from the firmware of various cards and filters them in order to recognize what are dependent from real failures and what are conse- quences of failures in subsystems different from that generating the seed. To make an example, let us assume that in a system the radiation emitted by a transmission laser is filtered by an optical filter and sent to the output fiber. A sensor measures the emitted radiation to verify laser performances, another sensor measures the optical power at the output of the filter to verify the filter integrity. If the laser goes down, both the sensors go over the threshold and the firmware of the transmitter produces two alarm seeds. One of t