A conventional start-time optimization scheme, which determines an optimal OSPF link weight set that minimizes the network congestion ratio at network operation start, is not suitable under failure. Link reinforcement through protection techniques is effective in providing robustness against link failure, but cannot be applied on every link due to resource limitations. This letter proposes a preventive start-time link-weight optimization scheme with link reinforcement considering all possible single-link failure scenarios. When the upper bound of the manageable congestion ratio is given, our proposed scheme determines a suitable link weight set at the network operation start that minimizes the number of links to reinforce, specifying the reinforced links, so as to guarantee a congestion ratio lower than or equal to the manageable congestion ratio upper bound under any single-link failure scenario. Numerical results demonstrate the effectiveness of the proposed scheme.