Division 4.1 Network layout

The SIS II architecture makes use of centralised services, which are accessible from the different Member States. For resiliency purposes these centralised services are duplicated to two different locations namely Strasbourg in France and St Johann im Pongau in Austria, respectively the CS-SIS, CU and backup CS-SIS, BCU.

The central units, main and backup, must be accessible from the different Member States. The participating countries may have multiple network access points, a LNI and a BLNI, to interconnect their National System to the central services.

Apart from the main connectivity towards the central services, the Communication Infrastructure must also support bilateral supplementary information exchange between the Sirene offices of the different Member States.