With the advances in switching technologies, ER switches are becoming popular since they perform better than EFCI switches. In the transitional period, EFCI and ER switches may coexist in the same ATM network. Hence, the efficiency of various ER schemes should be reevaluated in the mixed EFCI-ER environment, not only in the homogeneous ER environment. Also, some important implications are observed in the heterogeneous environments. Because the location of an ER switch in the topology is critical to its performance, some placement rules, which describe how to place the ER switches for network operators, are developed in order to achieve a better performance of the network. In summary, the results presented here should serve as an operational reference for service providers.