Project Specification: The main goal of this project is to optimize the tcp buffer size to make more efficient the file transfers with FTS3. The library that has been implemented provides a way to calculate this providing a source and a destination. This way, whoever is transferring the files does not have to know anything about the logic of how calculate it. In this project, I have done a library to make easy the access to PerfSONAR’s information between two hosts, calculating the optimized tcp buffer size and thereby to making more efficient the transfer of files. As part of my work, I have also tested the library to check if it actually improved the transfer throughput with tools as GridFTP and Globus.