Research And Implementation Of Enhancing Proxies For Satellit-based Forwarders In Space-Ground Integrated Networks

The space-ground integrated networks have become the development trend of future networks.However,different from the terrestrial Internet,satellite networks are characterized by some unique features such as dynamically changed topologies and limited onboard processing capabilities,making the traditional distributed routing protocols work inefficiently.In recent years,with the rise of new network technologies such as Identifier-based Networking and Software Defined Networking,how to achieve centralized routing in satellite networks has attracted great attention from both academia and industry.Nevertheless,most of the current solutions focus on the routing algorithms at the control plane,ignoring how to improve forwarders(e.g.,switches)at the data plane based on the special environment of satellite networks.To this end,the dissertation designs and implements a kind of enhancing proxies for satellite-based forwarders in space-ground integration networks,which act on the existing ground-based forwarders with the following three core functions completed:(1)loading and deleting the forwarding entries in time and in order according to the time-varying topologies of satellite networks;(2)collecting local network resource information for the controller;(3)coping with satellite link failures locally in a lightweight way.The purpose is to realize a sort of satellite-based forwarders for centralized routing that can support snapshot routing,status reporting,and link recovery.The work of this dissertation is summarized as follows.Firstly,a management mechanism for timeslice-based forwarding entries is designed and implemented,which needs to receive,store,read,parse,and execute the forwarding entries from the controller.Besides,corresponding modules are realized separately to load and delete different types of forwarding entries in time and order based on the related timeslice information,so that forwarding tables in the satellite-based forwarders are able to be updated as the timeslice switches according to forwarding policies determined by the controller.Secondly,to support the controller for acquisition resource information of the entire network,a corresponding collection mechanism is designed and implemented,which gathers link delay,throughput,the number of data packets sent and received by network interfaces,the address of neighboring nodes and so on.Then,the collected information is sent to the controller through two ways,periodical reporting and query responses,helping the controller to perform link failure awareness and routing optimization,and used for lightweight link recovery by satellite-based forwarders.Thirdly,to improve the recovery ability for link failures,a link failure handling mechanism is designed.When a link failure is detected by a satellite-based forwarder,data packets can be steered based on the pre-defined strategies to avoid the failure link.Besides,after being managed by the controller,the satellite-based forwarder can take appropriate actions based on the recovery strategies from the controller.Finally,a prototype containing 33 nodes is built to verify the functionalities of the enhancing proxies for satellite-based forwarders in space-ground integration networks.Extensive experiments are conducted and the results show that the designed enhancing proxies are able to load and delete forwarding entries in time and order based on the timevarying topology of satellite networks,gather network resource information for the controller,and cope with link failures locally.