Study On On-line Routing Algorithm Based On Offline-Optimal Computing

Internet Server Providers are facing the challenge of supporting IP services.Internet traffic engineering is emerging as a key tool to achieving the goals. InternetServer Providers desire that traffic engineering for the IP over ATM can implement inIP networks. MPLS is the technology of providing traffic engineering on thecoexistence of AIM and pure IP networks.These are many routing algorithms based on MPLS traffic engineering, a largenumber of which are only select paths for the traffic with the bandwidth request. Anew online routing algorithm, which is the applications to the result of the offlineoptimal computing, is proposed in this paper on the framework of offline optimizationadding online routing. The new routing algorithm can select paths for the QoS trafficand best-effort traffic.The framework of traffic engineering appeared in this paper has three majorcomponents: 1) offline optimal computing, based on the aggregate traffic matrix,which calculates the pre-allocation of link capacities for the every source-destinationpair;2) getting the path set from the result of the optimal computing, which isperformed offline;3) online routing, which select paths for the QoS traffic andbest-effort traffic in the path set, the QoS traffic will use the short path that can meetthe bandwidth request of the traffic, and best-effort traffic will use the path whichloads is light.The algorithm has been implemented in Networks Simulater2(NS-2). Thesimulation result show that the new online routing algorithm significantly outperformsthe CSPF(Constrained shortest path first) , which greatly increases the throughput ofthe best-effort traffics, and simultaneously guarantees the bandwidth of the QoStraffics.