In this paper, protection strategies of WDM networks are viewed from a cost perspective. The goal is to minimize the network cost while ensuring the network survivability. In WDM networks, multi fibers are kept in a duct and that duct can be treated as a link SRLG (Shared Risk Link Group). With the increase in size and number of shared risk link groups, capacity efficiency of shared-path protection decreases due to SRLG-disjoint constraints. As a result, a full SRLG failure protection is no longer a practical protection scheme. In a network, there are always some links with higher degree of usage compared to other links in the network.