One-to-many group communication is a performance bottleneck for high-performance data center applications, due to sending massive data from one source to hundreds of receivers. The state-of-the-art solutions utilize either electrical packet switch (EPS) or optical circuit switch (OCS) multicast to accelerate massive data disseminations. However, there exist competitions between multicast and unicast flows at core EPSes in the electrical multicast. Moreover, the optical multicast suffers from a non-negligible reconfiguration delay and exclusive optical links. In this paper we present iCAST, a system for reducing multicast flow completion time (MFCT) on a generic hybrid EPS/OCS network, which has multiple EPSes and OCSes supporting multicast. iCAST constructs multicast trees by integrating the electrical and optical multicast to fully utilize network resources, and seamlessly schedules flows between the static electrical and dynamic optical networks to reduce the configuration overhead. We evaluate the performance by implementing a small-scale hybrid EPS/OCS testbed and extending the high-performance framework MPICH to support iCAST. Experiments show that iCAST outperforms one order of magnitude in reducing MFCT compared with the ring algorithm. We also develop an event-based flow level simulator to evaluate the performance of iCAST at the scale of thousands of servers. Simulation results show that iCAST reduces the average MFCT by 32% and 28% compared to OCS and EPS respectively, and significantly outperforms binomial tree and ring algorithm by up to 64% and 46% respectively.

In this paper, we propose FlyCast, an architecture using the physical layer of free-space optics (FSO) to accelerate multicast communication. FlyCast leverages off-the-shelf devices (e.g. switchable mirror, beam splitter) to physically split the FSO beam to multi receivers on demand, which enables to build dynamical multicast trees in physical layer and accelerates multicast communications. We demonstrate the feasibility of FlyCast through our theoretical analysis and the proof-of-concept prototype.

In recent years, with the rapid development of satellite technology including On Board Processing (OBP) and Inter Satellite Link (ISL), satellite network devices such as space IP routers have been experimentally carried in space. However, there are many difficulties to build a future satellite network with current terrestrial Internet technologies due to the distinguished space features, such as the severely limited resources, remote hardware/software upgrade in space. In this paper, we propose OpenSAN, a novel architecture of software-defined satellite network. By decoupling the data plane and control plane, OpenSAN provides satellite network with high efficiency, fine-grained control, as well as flexibility to support future advanced network technology. Moreover, we also discuss some practical challenges in the deployment of OpenSAN.

SRAM-based FPGA is more sensitive to multiple bit upset, and the possibility of accumulation of memory's upset is high. In order to improve the ability that SRAM-based FPGA is more stable to multiple upset, this paper presents a new type design of multiple errors correction. The design combines BCH(15,7) code which can correct two errors and the improved TMR technology and achieves detecting and correcting multiple bit upset. Compared with the classical Hamming codes and extended Hamming codes, it has the advantage of correcting multiple bit upset. And compared with the traditional TMR, it can effectively determine the validity of the data after voting. Meanwhile, the design writes back the right data when error happens to avoid the accumulation of errors.