The Common Network Information Service (cNIS) has been developed as a component of the unified platform of services supporting multi-domain workflows in the GÉANT network. The prior motivation of cNIS was an urgent necessity of gathering and storing unified information about the whole topology of the GÉANT European network. Within the scope of the GÉANT project, a lot of network supporting tools are being developed. Currently a part, and finally all of them, use cNIS as a central network topology data repository.

The cNIS was expected to be a central repository, but actually it is not only a database. Apart from the internal functionality required for populating, validating, and updating the database, cNIS is equipped with modules for analyzing the topology data and presenting it in various formats: tabular, graphical (two different types of visualization) and structural (XML, NMWG), so that the gathered data can be presented to users and processed by external applications.

The cNIS is able to store topology data not just for a domain's IP infrastructure, but also for other network technologies (Ethernet, SDH). Automatic population is a significant feature of the cNIS, since it simplifies the work of network administrators (NRENs and others). As a result, cNIS delivers a mechanism for automatic discovery of the IP, Ethernet and SDH technologies.