A transmission control system for controlling management processes, such as shaping, is presented. The management processes are directed to data streams that are parts of data traffic transmitted via a link aggregation group having egress ports in separate functional entities of a network element. For each data frame of the data traffic, it is detected whether the data frame belongs to any of the data streams. Data frames belonging to none of the data streams are forwarded so that these data frames are distributed between the functional entities according to a link aggregation rule. A management rule is maintained for indicating, for each of the data streams, a stream-specific functional entity that runs each management process directed to the data stream. Each data frame belonging to one of the data streams is forwarded to the appropriate stream-specific functional entity in accordance with the management rule.