Study On Bandwidth Guaranteed Routing In MPLS Network

ABSTRACT Real-time multimedia traffic and telecommunication services can experiencesevere quality degradation in QoS-unaware networks such as the Internet, whichprovides best-effort services only. ISPs need a QoS-aware dynamic routing algorithmto overcome this problem. MPLS is a promising technology that has the potential toprovide such solution. However, QoS-aware framework and routing algorithm are tobe developed to achieve this goal. In this thesis, we present a new framework andalgorithm for dynamically setting up paths with bandwidth guarantees. Inspired by theMinimum Interference Routing (MIRA) and Profile-Based Routing, our work uses apriori knowledge of the network, which is called "traffic profile". The traffic profilecan be obtained by measurement or service level agreements (SLAs). It roughlyrepresents the future traffic distribution in the network. Our framework has three major components: offline routing, based on thenetwork running statistics, which calculates the admission thresholds for eachpre-defined traffic class and the pre-allocation of link capacities for the online routingphase; online routing, based on offline routing and the current network state, whichperforms path selection and then sets up LSPs in MPLS network; and thecorresponding link state advertisement protocol, which distributes the link stateinformation throughout the whole network. The online algorithm is designed simpleenough to keep the computational requirement per flow setup as low as possible,while the offline calculation part is to solve a multi-commodity flow problem, whichis a time-consuming process but can be executed offline. And the link stateadvertisement protocol keeps the link state database on each of the routers in thewhole network up-to-date. We have implemented our QoS framework in Network Simulator2 (NS-2) andcarried out extensive simulations. The simulation results show that the new QoSframework and routing algorithm significantly outperforms the conventional routingalgorithms like shortest path first on the metrics such as the fraction of requests routedand the fraction of requested bandwidth routed. Moreover, the major contribution ofour work is that it provides a reliable mechanism to dynamically set up bandwidthguaranteed LSPs in a MPLS-based ISP network.