By combining the capacity of optical fiber networks with the wireless networks, FiWi networks form a powerful platform for the support and creation of emerging as well as future unforeseen applications and services. FiWi supports very high speed transmission rate, hence any kind of failure may result in significant data loss. To prevent this, there is a requirement to design a more reliable network. In FiWi networks there are two types of failures: ONU (Optical Network Unit) level failure and OLT (Optical Line Terminator) level failure. In this paper, the authors present comparison of backup ONU’s connected from each segment in different topologies, to handle segment level failure. Comparison is done on the basis of reduced blocking probability.