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Optical burst switching (OBS) is a promising technique for supporting high-capacity bursty data traffic over optical wavelength-division-multiplexed (WDM) networks. A label-switched path can be established to forward a burst control packet (BCP) if each OBS node is augmented with an IP/MPLS controller. Such a network is called a labeled OBS (LOBS) network, and it can exploit the explicit routing and constraint-based routing properties supported in the MPLS framework to perform traffic and resource engineering. However, the burst-loss probability (denoted as BLP) can be large if the traffic is not properly engineered in a LOBS network, especially after a failure occurs. In this paper, we propose to use pre-planned global rerouting to balance network load and to restore bursts after a link fails. We apply optimization techniques to pre-plan explicit backup routes for failure scenarios. Our objective is to achieve optimal load balancing both before and after a failure such that the network state can still remain stable with minimum BLP when failure occurs. We apply the pre-planned global rerouting method in a LOBS network and study the performance of different rerouting schemes on some typical network topologies. Our illustrative numerical examples show that the BLP can be significantly reduced by 25%-99% (when the average link load is less than 0.5) using globally rerouted backup routes, when compared with the scheme without global rerouting. We also observe that the BLP is reduced by 20%-65% (when the average link load is less than 0.5) if the rerouting is done using optimization techniques, when compared with shortest-path routing.