Widespread use of cluster systems in diverse set of applications has spurred significant interest in providing high performance cluster interconnects. A major inefficiency in utilizing such interconnects has been the send/receive communication overheads at the sender/receiver hosts. Various techniques such as User-Level Communication (ULC) have been proposed to mitigate this communication inefficiency. However, due to recent security breaches, focus on cluster communication security research has spurred. Such research is non-trivial due to the high-speed nature of the cluster interconnect. This paper surveys the four most popular cluster interconnects used in Top500 supercomputers and explores possible schemes to ensure secure cluster intra-communication encompassing the host processor, secure coprocessor and the Network Interface Card (NIC) by illustrating its challenges in doing so. We then compare these schemes in terms of host processor offload, end-to-end latency, security transparency and cryptographic processing performance. Then we give an overview of security issues for those cluster interconnects designs.