  Modern radio astronomy relies on very large amounts of data that need to be
transferred between various parts of astronomical instruments, over distances
that are often in the range of tens or hundreds of kilometres. The Square
Kilometre Array (SKA) will be the world's largest radio telescope, data rates
between its components will exceed Terabits per second. This will impose a huge
challenge on its data transport system, especially with regard to power
consumption. High-speed data transfers using modern off-the-shelf hardware may
impose a significant load on the receiving system with respect to CPU and DRAM
usage. The SKA has a strict energy budget which demands a new, custom-designed
data transport solution. In this paper we present SoftiWARP UDP, an unreliable
datagram-based Remote Direct Memory Access (RDMA) protocol, which can
significantly increase the energy-efficiency of high-speed data transfers for
radio astronomy. We have implemented a fully functional software prototype of
such a protocol, supporting RDMA Read and Write operations and zero-copy
capabilities. We present measurements of power consumption and achieved
bandwidth and investigate the behaviour of all examined protocols when
subjected to packet loss.
