3. CS-1 overall functional plan

This plan is detailed in Recommendation Q1213 for RI Capacity Set 1 [2] . It models network functionality from a global, network-wide perspective. It corresponds to the programming interface. In this plane, the services identified in the service plane are decomposed into service elements and then redefined in natural language in terms of the broad, modular network functions required to support them. These functions are neither service-specific nor service-element-specific. These standardized, reusable building blocks are therefore defined independently of any service or implementation, and are known as service independent building blocks (SIBs).