A method of controlling a radio access network entity of a data unit communication network is described, said radio access network entity being involved in providing a transport service to a radio terminal of said data unit communication network, said transport service being characterized by a set of values associated with respective service quality parameters, said method comprising: monitoring (S30) a communication quality at the radio access level of a communication between said terminal and an access point of said radio access network, and setting (S31) a congestion indication marking in data units of said transport service if said communication quality fulfils a radio communication degradation condition.