Electrosmart.Net

NGN - Next Generation Network

Next Generation Networking (NGN) broadly refers to IP telecommunication core and access networks to be deployed over the next 5-10 years.

The ITU-T definition of a Next Generation Network is " a packet-based network able to provide services including Telecommunication Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies.

NGN offers unrestricted access by users to different service providers. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users.

NGN Architectural Changes

NGN involves three main architectural changes:

Core Network
Wired Access Network
Cable Access Network

NGN Core Network Changes

In the core network, NGN implies:

Consolidation of several (dedicated or overlay) transport networks into one core transport network (IP or Ethernet).
Migration of voice from a switched architecture (PSTN) to VoIP
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).

NGN Wired Access Network Changes

In the wired access network, NGN implies the migration from the "dual" legacy voice next to xDSL setup in the local exchanges to a converged setup in which the DSLAMs integrate voice ports or VoIP, allowing to remove the voice switching infrastructure from the exchange.

NGN Cable Access Network Changes

In cable access network, NGN convergence implies:

Migration of constant bit rate voice to CableLabs PacketCable standards that provide VoIP and SIP services. Both services ride over DOCSIS as the cable data layer standard.
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.
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 technologies including:

Internet Protocol (IP)
Multiprotocol Label Switching (MPLS)
Session Initiation Protocol (SIP) - seems to be taking over from ITU-T H.323 at the application level,

SIP or H.323

SIP is a useful tool for the "local loop" and H.323 is like the "fiber backbone".

With the most recent changes introduced for H.323, it is now possible for H.323 devices to easily and consistently traverse NAT and firewall devices, opening up the possibility that H.323 may again be looked upon more favorably in cases where such devices encumbered its use previously.

Most Telcos are extensively researching and supporting IMS, which gives SIP a major chance of being the most widely adopted protocol.

Softswitch

For voice applications one of the most important devices in NGN is a Softswitch - a programmable device that controls Voice over IP (VoIP) calls.

The most important function of the Softswitch is creating the interface to the existing telephone network, PSTN, through Signalling Gateways (SG) and Media Gateways (MG).

A softswitch enables correct integration of different protocols within NGN.

Softswitch is defined differently by the different equipment manufacturers, each having somewhat different functions.

Gatekeeper

Gatekeeper was the term originally used to refer to a VoIP device, which converted (using gateways) voice and data from their analog or digital switched-circuit form (PSTN, SS7) to the packet-based one (IP). It controlled one or more gateways. It is now termed the Media Gateway Controller (MGC).

Call Agent

A Call Agent is a general name for devices/systems controlling calls.

IMS

The IP Multimedia Subsystem (IMS) is a standardised NGN architecture for an Internet media-services capability defined by the European Telecommunications Standards Instititue (ETSI) and the 3rd Generation Partnership Project (3GPP).

Reference: Wikipedia

Next: IMS Network Infrastructure