Research On Cloud Network Resource Sharing And Isolation Methods For Virtual Datacenter

The rapid revolution of cloud computing and its services make cloud datacenter large-scale,automatic and multi-tenant.More and more large,middle or small enter-prises move their applications into cloud,deployed on virtual machine,connected by network topology,forming virtual datacenter,named VDC.With the explosive growth of Internet data,service applications tend to be built on cloud such as search,MapRe-duce,storage,and high performance computing.etc.This leads to frequent communica-tion among cloud servers.The east-west traffic pattern is becoming more increasingly common than that of south-north.As datacenter network is scarce in cloud,the research of sharing and isolation of cloud resources could have direct impact on application QoS.Cloud service providers want to improve the total network utilization while providing VDC performance guarantees.However,cloud network is homogeneous and large-scale,existing sharing and isolation methods face some challenges such as flexibility,scalability,fairness,network utilization and allocation efficiency,etc.This dissertation aims to solve that how to accommodate co-existing heterogeneous virtual network on physical network,and our contributions are summarized as follows:(1)NXT-NVF,a network virtualization framework is proposed to achieve flexi-ble and efficient cloud network resource delivery,supporting VDC-based application-aware networking with bandwidth guarantees for cloud datacenter.It can not only help enterprise applications move their network environments into cloud datacenter,but also support application-aware networking.By abstracting virtual network as switch-centered SCG model,VDC can self-define its topology and forwarding rules so that vir-tual network can be flexibly built.A heuristic switch-centered VN to physical network mapping approach is introduced,allowing tenants to provide their applications with a cloud networking environment that is very similar to its enterprise environment,thereby increasing the possibility of preserving similar performance.As many service types in-cur severe scalability problem in switch state maintenance,to make state maintenance scalable at switches,combined SDN with source routing technology,both self-define fordwarding paths and application-aware networking are enabled in system implemen-tation.Finally,the simulation results demonstrate that our VDC allocation achieves high network utilization and low time complexity.(2)In the above framework,a virtual network embedding algorithm,using Branch-and-Price to maximize redundant network utilization,is proposed to efficiently improve network utilization.Mapping virtual network onto underlying physical network is re-duced to the Minimum Cost Multi-commodity Flow Problem,then establish the mixed integer programming model.Based on Dantzig-Wolfe decomposition,the original problem is decomposed into a main problem based on path and a sub-problem based on shortest path.We calculate the optimal solution between the linear relaxation of the main problem and sub-problem iteratively through column generation.Edge is used for branching.The simulation results show that our VDC allocation achieves maximum per-VDC redundant network allocation and low time cost.(3)In the above framework,a bandwidth isolation method based on per-VDC fair-ness,is proposed.It provides minimum bandwidth guarantees and fully utilizes the spare bandwidth from unreserved capacity to make bandwidth isolation among VDCs.To achieve redundant bandwidth allocation,considering that the intra-VDC bandwidth allocation takes precedence over the interVDC bandwidth allocation,we propose hier-archical max-min allocation algorithm based on per-VDC fairness;To achie-ve scalable per-VDC bandwidth guarantees,Nxt-Freedom implements congestion control mecha-nism in server hypervisors,by introduce distributed bandwidth enforcer,avoiding main-taining resource reservation status in physical switches.In addition,by means of SDN technology,it quickly pinpoints bottleneck links,further adjusts the sending rates of the flows of virtual machine,finally enforces network performance guarantees among VDCs.Through evaluation of a prototype,Nxt-freedom achieves perVDC performance isolation,and high utilization of cloud network.