A method for obtaining information about a transmission capability of a transmission link (TL) is disclosed. A sending entity (SE) sends data packets at a sending rate to the transmission link (TL), which transmits the data packets according to its transmission capability to a receiving entity (RE) receiving the data packets at a receiving rate. The sending rate is modulated with a rate modulation and the following steps are executed by an analysis entity (AE): obtaining the sending rate, obtaining the receiving rate, comparing the obtained sending rate and the obtained receiving rate to determine a relation of the obtained sending rate and the obtained receiving rate and to determine an appearance of the rate modulation of the sending rate in the obtained receiving rate, and obtaining the information about the transmission capability based on the determined relation and the determined appearance of the rate modulation.