Fast development from last few years in wireless senor network has create great impact on researcher and motivated by various real time issues. There are huge numbers of sensors deploy in network which sense the neighbouring information and processed the gathered data to the base station, processing speed, storage and communication bandwidth. Because of these constraints fast transmission, fault tolerant, load balancing mechanism and energy efficient routing are critical requirements in WSNs to

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... increase the network lifetime. By considering this limitation it is necessary to design novel energy aware and fault tolerant routing protocol for heterogeneous sensor network. In this survey paper various existing techniques are studies and list out the research challenges.