Evaluation of multi-source downloads for FTS

The data transfer in the Grid at CERN (the European Organization for Nuclear Research) has seen constant improvement, be it through optimizing the existing tools, GridFTP and GFAL2 or by adding new tools such as XRootd. Unfortunately, all these have reached the maximum limit in terms of throughput. They are limited not by the network infrastructure, but by the fact that they use a single source for transfers, despite the existence of multiple replicas. In this paper we take on the challenge of evaluating the effects of using multiple sources, over the throughput, by comparing the download speed of the tools mentioned above with Aria2 and an under development version of XRootd, both supporting the use of multiple sources.