A network includes a first node and a second node and data frames are transmitted from the first node to the second node. Each of the data frames carry information belonging to one of a plurality of data flows. In a flow control unit (125) there is an estimate or measure determining unit (1201) for determining for each of the data flows, at the ends of first time periods having a predetermined first length, an estimate of or a measure representing the total number of received data frames that have been faulty during the first time period. A reference calculating unit (1101) is connected to the estimate or measure determining unit for calculating, based on the determined estimate or measure, a bandwidth capacity reference value determining the currently maximum allowable bandwidth for transmission from the data transmitting node to the data receiving node. The first node can be a radio network controller and the second node a radio base station, the data frames forwarded in an HS-DSCH over an Iub interface.