Internal and external network communications are essential for CERN. Internally, no less than 35 000 km of optical fibre provide network connectivity throughout the CERN sites. The CERN Data Centre is also the host of the CERN Internet eXchange Point (CIXP), a carrier-neutral exchange point, through which CERN played a central role for the internet’s development: in 1991, 80% of the internet capacity in Europe for international traffic was installed in the CERN Data Centre.
The CERN Data Centre and its remote extension, installed at the Wigner Research Centre for Physics in Budapest, Hungary, also rely heavily on the quality of the network connections linking them. They are connected via three independent and dedicated 100-Gb/s (gigabit per second) fibre-optic lines. Network latency (the time taken between sending data and receiving on the other end) between the two sites, which are 1200 km apart, is about 25 milliseconds.
One of the most impressive components of the Worldwide LHC Computing Grid is its networking and connectivity. It can initiate the distribution of data to the hundreds of collaborating institutes worldwide thanks to the excellent connectivity and dedicated networking infrastructure set up at CERN and subsequently worldwide. Since the beginning of the second four-year-long LHC running period, the data transfer rates around the globe also reached new peak rates – between 30 and 40 gigabytes per second continuous rates, around a factor of two higher than had been typical during the LHC Run 1.