Improved network design techniques are provided. For example, a technique for designing a protection capacity to be reserved in a network comprises the following steps/operations. One or more link capacities associated with a network topology are obtained. The network is assumed to have no pre-existing working traffic. A capacity partition including a working capacity portion and a protection capacity portion is determined for at least one link in the network topology. The protection capacity portion is reserved for rerouting working traffic upon a failure and enabling control over the number of backup tunnels, associated with the at least one link, on which working traffic can be rerouted. Determining the capacity partition substantially guarantees at least one of a minimal failure restoration time and a minimal overbuild. A minimal overbuild may include an overbuild equivalent to no more than two times an overbuild required for an optimal solution.