Next generation networks (NGNs) comprise two main elements: a next generation core and next generation access.
The core network element refers to the core IP network and is characterized by replacement of legacy transmission and switching equipment with IP technology in the core or “backbone” network. The elements are of 3 types:
1) connectivity components: e.g. routers, switches, and digital subscriber line multiplexers (DSLAMs);
2) application servers: e.g. SIP (Session Initiation Protocol) Registrar, softswitches;
3) links between connectivity components and application servers, e.g. STM-1, Gigabit Ethernet, or 10GE.