The present invention relates to a method and node arrangement for evaluating available conditions of a data path between a sending node and a destination node in a data communications network by means of an active measurement process comprising one or more measurement sessions. The data path and sending node comprises a sending node interface. The method involves performing a measurement session of said data path for determining a measurement result, and estimating one or more available conditions of a data path using the measurement result and one or more initial parameter values as input in a calculation algorithm. The method further comprises setting one initial parameter value for the calculation to a maximum bandwidth capacity based on the lowest bandwidth capacity value of the interfaces of both nodes sending said probe packet sequences during said measurement session.