What is NGN?
As per ITU NGN is a packet based network which is able to provide multimedia telecom services and able to make use of multiple broadband, QoS enabled transport technologies in which service related functions are independent from underlying transport related technologies. It offers unrestricted access by users to different service providers. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users . From a practical perspective, NGN involves three main architectural changes that need to be looked at separately:
In the core network, NGN implies a consolidation of several (dedicated or overlay) transport networks each historically built for a different service into one core transport network (often based on IP and Ethernet). It implies amongst others the migration of voice from a circuit-switched architecture (PSTN) to VoIP, and also migration of legacy services such as X.25, Frame Relay (either commercial migration of the customer to a new service like IP VPN, or technical emigration by emulation of the "legacy service" on the NGN).
The following diagram depicts the concept of NGN.
Current Gen networks NGN
In NGN basically the call control (i.e. signaling) and the switching is separated out in different layers and between these layers open interfaces are used. The call control functionality is realised by the component which is called call server or softswitch or media gateway controller and the interfaces to the existing PSTN switches is done with the help of media gateways for voice transport and by signaling gateways for signaling transport. For switching and transport of the packets existing IP/MPLS backbone is used. With NGN architecture the new and innovative services can be given very fast and cost effectively. Also the capital expenditure and operational expenditure come down drastically.
Generic reference diagram for IP TAX is as below:
Based on the above GR the implantation plan is as below:
•Setting up Two Soft Switches at New Delhi and Chennai and Signalling Gateways at New Delhi, Chennai, Kolkotta and Bangalore
•Providing Trunk Media Gateways (TMGs) at 21 Level-1 locations
•Providing one Announcement Servers in each IP domain i.e. one at New Delhi and one at Chennai.
•Billing interface to Centralized Billing Server at Chennai.
•NMS at Chennai with FCAPS
(Fault,Configuration,Accounting,Performance,Security) capabilities. No separate NTP server is being used in IP TAX, the existing NTP server of our data network will be used for synchronization.
Following architecture is going to be installed :
In the wired access network, NGN implies the migration from the dual system of legacy voice next to xDSL setup in the local exchanges to a converged setup in which the DSLAMs integrate voice ports or VoIP, making it possible to remove the voice switching infrastructure from the exchange. In cable access network, NGN convergence implies migration of constant bit rate voice to Cable Labs Packet Cable standards that provide VoIP and SIP services. Both services ride over DOCSIS as the cable data layer standard. In an NGN, there is a more defined separation between the transport (connectivity) portion of the network and the services that run on top of that transport. This means that whenever a provider wants to enable a new service, they can do so by defining it directly at the service layer without considering the transport layer - i.e. services are independent of transport details. Increasingly applications, including voice, will tend to be independent of the access network (de-layering of network and applications) and will reside more on end-user devices (phone, PC, Set-top box).
Underlying technology components
Next Generation Networks are based on Internet...