The main advantages of Time Division Multiple Access (TDMA) based networks are twofold, as opposed to e.g. CSMA-based approaches: TDMA networks can provide real time guarantees on the delivery time of messages, and their operation is energy efficient, due to the fact that nodes may sleep most of the time. The logic of the application may be present in the network hierarchy, e.g. data collecting application often use tree topology, while alarm systems may use a ring topology instead. In this paper design problems of fault tolerant cyclic networks are discussed: we define a fault tolerant cyclic architecture and provide efficient heuristic algorithms to solve the (NP-hard) problem of finding such architectures.