Network Hierarchy
It would be generally too expensive to build networks so that each user would be connected directly to each other user. Hence networks are build with as much joint use of resources as possible. This creates so called access hierarchy with the following parts:
- Terminal Equipment which provide the users and applications the interface and connectivity to access networks.
- Access Networks which provide the network connection and communication resources for local telephone, mobile and business customers.
- Basic Network which is jointly used to interconnect access networks, gateways to other carrier networks and network elements providing services and to transfer data between them.
Network Control is needed to create, distribute and manage network resources and the services available over the networks.