There are about 70 core network sites of X-WiN distributed throughout Germany. The sites are primarily located in the computing centres of universities and research facilities. Some core network sites are accommodated in co-location facilities.

DFN-Verein operates at each core network site DWDM-systems, which are interconnected via the optical platform, and IP-routers, that employ the optical platform to connect to the router platform for IP-packet switching.

DFN-Verein organizes the core network sites in its own responsibility. This complete control provides unlimited co-location with service-providers and direct access to the complete scope of functionality of the DWDM-systems as well as the IP-routers.

DFN-Verein continuously extends the core network sites according to its users' demand.