The design of efficient communication mechanisms for small satellite networks is a challenging task, requiring the definition and implementations of specific protocols and architectures appropriate to space's critical conditions. In this paper, we have selected XSTP (eXtended Satellite Transport Protocol) as candidate protocol for nanosatellite networks. Foremost, we implement XSTP in NS-2 simulator. The initial simulations were done in a LEO satellite network scenario. According to our simulations, XSTP was shown to attain higher effective throughput, much lower overhead, and better channel efficiency as compare to TCP clones, in case of high BER conditions. As to low BER environment, all protocols have a comparable performance in terms of channel efficiency