The application of SpaceFibre network standard and ESDP transport protocol (the previous name is «STP-2») for streaming data transfer in onboard spacecraft networks is considered in the paper. The paper demonstrates that traffic management is needed in SpaceFibre networks. To solve this problem Adaptive Data Streaming Service (ADSS) could be used. ADSS Traffic management is based on the traffic control via changing of SpaceFibre configuration parameters and ESDP protocol’s mechanisms. Genetic Algorithm (GA) is proposed to determine new SpaceFibre configuration parameters. The key function of GA is the quantity estimation of streaming data through SpaceFibre. To the best of our knowledge, there is no such methods for SpaceFibre networks. It is for this reason that the mathematical method of quantity estimation has been developed and presented in the paper. The math model of streaming over SpaceFibre was also developed for this method. It is based on Markovian chain. Examples of calculations are given. The proposed method could be used for SpaceWire networks with STP-ISS-14 protocol.