Online traffic engineering for MPLS networks

[摘要] ENGLISH ABSTRACT:The Internet is fast evolving into a commercial platform that carries a mixture of narrow- and broadband applicationssuch as voice, video, and data. Users expect a certain level of guaranteed service from their serviceproviders and consequently the need exists for efficient Internet traffic engineering to enable better Quality ofService (QoS) capabilities.Multi-protocol Label Switching (MPLS) is a label switching protocol that has emerged as an enabling technologyto achieve efficient traffic engineering for QoS management in IP networks. The ability of the MPLSprotocol to create explicit virtual connections called Label Switched Paths (LSPs) to carry network trafficsignificantly enhances the traffic engineering capabilities of communication networks. The MPLS protocolsupports two options for explicit LSP selection: offline LSP computation using an optimization method anddynamic route selection where a single node makes use of current available network state information in orderto compute an explicit LSP online.This thesis investigates various methods for the selection of explicit bandwidth guaranteed LSPs throughdynamic route selection. We address the problem of computing a sequence of optimal LSPs where each LSPcan carry a specific traffic demand and we assume that no prior information regarding the future traffic demandsare available and that the arrival sequence of LSP requests to the network is unknown. Furthermore,we investigate the rerouting abilities of the online LSP selection methods to perform MPLS failure restorationupon link failure.We propose a new online routing framework known as Least Interference Optimization (LIO) that utilizesthe current bandwidth availability and traffic flow distribution to achieve efficient traffic engineering. Wepresent the Least Interference Optimization Algorithm (LIOA) that reduces the interference among competingnetwork flows by balancing the number and quantity of flows carried by a link for the setup of bandwidthguaranteed LSPs in MPLS networks.The LIOA routing strategy is evaluated and compared against well-known routing strategies such as the Minimum Hop Algorithm (MHA), Minimum Interference Routing Algorithm (MIRA), Open Shortest PathFirst (OSPF) and Constraint Shortest Path First (CSPF) by means of simulation.Simulation results revealed that, for the network topologies under consideration, the routing strategies thatemployed dynamic network state information in their routing decisions (LIOA, CSPF and MIRA) generallyoutperformed the routing strategies that only rely on static network information (OSPF and MHA). In mostsimulation experiments the best performance was achieved by the LIOA routing strategy while the MHA performedthe worse. Furthermore we observed that the computational complexity of the MIRA routing strategydoes not translate into equivalent performance gains.We employed the online routing strategies for MPLS failure recovery upon link failure. In particular weinvestigated two aspects to determine the efficiency of the routing strategies for MPLS rerouting: the suitabilityof the LSP configuration that results due to the establishment of LSPs prior to link failure and theability of the online routing strategy to reroute failed LSPs upon link failure. Simulation results revealedsimilar rerouting performance for all online routing strategies under investigation, but a LSP configurationmost suitable for online rerouting was observed for the LIOA routing strategy.

[发布机构] Stellenbosch University