CERN External Network evolution for LHC Run3 and Run4

As from 2019, the LHC accelerator and its four major Experiments will undergo major upgrades that will dramatically increase the amount of data produced, data that not only has to be collected and stored at CERN, but also has to be sent to collaborating institutes. This document reviews CERN’s connectivity to collaborating institutes and to the Internet in general and documents the changes and upgrades that will be necessary to meet the challenges from 2021 with an outlook to the further changes to meet the needs of the High Luminosity LHC era.