The QoS Control Research Of Space-Ground Network Based On DiffServ Over MPLS

Space communication has many distinctive characteristics, such as long distance, complicated environment, variable time delay, high data corruption rates, heterogeneous structures, and limited ability and resources of space craft etc. But with the development of space science and technology, the Deep Space Communications will no longer merely in the application of scientific data, the scope of communication will be developed to a comprehensive business of a variety of business combined including voice services, video images, still images etc. Therefore, with the increasing development of space communication, the Quality of Service of space network has become a meaningful research subject. Accordingly this paper proposes a QoS control method based on DiffServ over MPLS of the Deep Space Communications.First the paper discussed in detail the Consultative Committee for Space Data Systems (CCSDS) Advanced Orbiting Systems (AOS), researched its eight traffic types and their Data Unit Format one by one. Then analyzed Several major QoS (Quality of Service) mechanisms which could realize the QoS guarantee including IntServ (Integrated service)model, DiffServ (Differentiated Service) model and MPLS (Multi-Protocol Label Switching) model and their own Features. MPLS is a promising core network technology and a new network exchange standard of IP high-speed backbone network, which belongs to the third-layer network architecture, and its well fast forward of second-tier technology and Flexible routing of third-layer are very suitable for the particular space communications network, especially its combination with DiffServ that is quickly gathering momentum as a good network quality of service model.On the basis of analyzing the network architecture and traffic types provided by CCSDS, according to the way of data transmission and split of AOS provided by the literature, this paper abstracts encapsulating program of IP packet in the CCSDS AOS. Owing to the IP packets belong to Internet service, the encapsulating program selects Internet service, Encapsulation service, Multiplexing service and Virtual Channel Access service of AOS to package the IP packets; According to the characteristics of Satellite network and the characteristics of applications and requirement in the future, made a QoS control program which the DiffServ over MPLS technology is applied to the deep space network. In this program, by the CCSDS AOS encapsulating program, the IP packets based on DiffServ over MPLS firstly are encapsulated to the Encapsulation Protocol Data Units via the Encapsulation Service, then the Encapsulation Protocol Data Units are Multiplexed to the Multiplexing Protocol Data Unit together with Multiplexing Service Data Units, and then the Virtual Channel make lots of data flows share a virtual channel in the Virtual Channel Access. To achieve simple, reliable and stable business needs when the data flows through the space channel, the data flows are placed in a fixed length Virtual Channel Protocol Data Unit in this layer. Finally, place the virtual channel protocol data unit into physical channel to transport after error control. Due to delay, delay jitter and packet loss rate are the key quality of service attributes which affect the advantages and disadvantages of the space communications network performance, especially for the Audio and video business having higher demands for quality of service, this paper make a simulation using network simulation software NS2 on the three respects for the QoS Control program. The simulation results show that the method better meet the different needs of different space users in the deep space network for QoS on delay, delay jitter and packet loss rate.