Network topology design considering detour traffic caused by link failure

We present a network topology and link capacity design method that minimizes the total cost with the constraint that any link utilization is kept below a given target level in the case of a single-link failure. Although many traffic engineering techniques have been investigated to balance the link load by explicitly setting the packet routes, the given network topology and link capacity were fixed in those studies, whereas ISPs can design them freely in practice. We discuss the topological properties of networks if our method is applied to backbone networks in the USA and Japan.