In recent years, multistage networks have been suggested as efficient tools in interconnection networks and have been studied by many researchers. In this direction many fault tolerant networks have been introduced and different studies have been performed in the field of evaluating performance of these networks. One of these networks is called Fault tolerant Double Tree (FDOT) networks which have proper efficiency in addition to the feature of cost-efficiency. Most studies performed on different kinds of multistage networks in the past have either been in the form of simulation or in the form of analytical modeling, but they have been performed in very special conditions. We have tried in this research to study the FDOT networks through analytical modeling. In this article a model has been provided for evaluating the efficiency of these networks that can evaluate the efficiency of different kinds of these networks having any size and buffer capacity under uniform traffic.
