The National Aeronautics and Space Administration (NASA) has been working toward space Internet and Interplanetary Internet (IPN) using appropriate network architecture and protocols [1]. As the widely deployed network protocol suite, the Transmission Control Protocol/Internet Protocol (TCP/IP) has been very successful in today's Internet operations. But TCP experiences severe performance degradation in space communications mainly because of the vast differences between terrestrial and space operating environments [2]. Although the feasibility of operating space communications using the Internet type of protocols has been a source of contention within NASA [1], a large number of alternative transmission control protocols and algorithms have been developed for space and other environments with similar communication conditions [2]-[8]. In [9], Wang et al. provides a comprehensive and comparative discussion for some of these protocols.