Research And Implementation Of The Virtual Network Function Service Chain In Space Networks

The Space-Air-Ground Integrated Networks(SAGIN)is one of the important elements of China's 13 th Five-Year Plan for science and technology innovation,which plays a crucial role in the expansion of national strategic interests.Satellite networks are characterized by complex topology,dynamic link changes,scarce resources and limited processing capacity.How to optimize network resource allocation and scale back resource consumption is significant for satellite networks to scale back in operation prices and improve resource utilization.Software Defined Network(SDN)and Network Function Virtualization(NFV)are very revolutionary network technologies which are driving continuous innovation in network architecture and network service models.Service Function Chain(SFC)is a set of network functions that are executed in a specific order.With SFC,operators have the flexibility to provide customized services to various types of users.Segment Routing(SR)is an easily scalable and compatible source routing technology proposed by Cisco.With the help of the above-mentioned emerging technologies,this thesis jointly considers routing and resource allocation in Low Earth Orbit(LEO),and completes SFC routing through Virtual Network Function(VNF)dynamic deployment and scheduling.The following research is done in this thesis:1.A heuristic VNF dynamic deployment algorithm is proposed.In this thesis,we consider the bandwidth of LEO network,computing resources of LEO satellites,and the allocation cost of VNFs on the network performance,and propose a heuristic VNF dynamic deployment algorithm with the optimization objectives of maximizing the number of service requests that can be satisfied and minimizing the number of VNFs deployed.Experiments show that the algorithm proposed in this thesis is effective in improving the service success rate and reducing the number of VNF deployments,and the utilization of node resources is also improved.2.A VNF dynamic release algorithm that adapts to changes in network load is proposed.Over-redundant VNFs will not only not bring more benefits,but will greatly reduce resource utilization and increase the energy consumption of satellites.The VNF dynamic release algorithm proposed in this thesis can release the redundant VNFs in the network and recover the computing resources of the satellites,thus improving the resource utilization and reducing the energy consumption of the satellites.3.A segmented routing-based simulation system is implemented.This system implements SFC routing with SDN network architecture as the core and SR as the transmission basis of data forwarding plane.This is a network function hierarchical model that separates data transmission and control.In the control plane,it completes the dynamic deployment of the VNF according to the service function chain sequence of the service request through the global awareness capability of SDN,calculates the forwarding path and issues the label stack.In the data forwarding plane,it guides the forwarding of data packets through SR,which can reduce the flow table interaction between the control plane and the data plane.