Next Generation Networking

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Next Generation Networking (NGN) is a broad term to describe some key architectural evolutions in telecommunication core and access networks that will be deployed over the next 5-10 years. The general idea behind NGN is that one network transports all information and services (voice, data, and all sorts of media such as video) by encapsulating these into packets, like it is on the Internet. NGNs are commonly built around the Internet Protocol, and therefore the term "all-IP" is also sometimes used to describe the transformation towards NGN.

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[edit] Description

According to ITU-T the definition is

A Next Generation Network (NGN) 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. 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.[1]

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).
  • 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.
  • 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.

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).

[edit] Underlying technology components

Next Generation Networks are based on Internet technologies including Internet Protocol (IP) and Multiprotocol Label Switching (MPLS). At the application level, Session Initiation Protocol (SIP) seems to be taking over from ITU-T H.323.

Initially H.323 was the most popular protocol, though its popularity decreased in the "local loop" due to its original poor traversal of NAT and firewalls. For this reason as domestic VoIP services have been developed, SIP has been far more widely adopted. However in voice networks where everything is under the control of the network operator or telco, many of the largest carriers use H.323 as the protocol of choice in their core backbones. So really 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. Nonetheless, most of the telcos are extensively researching and supporting IMS, which gives SIP a major chance of being the most widely adopted protocol.

For voice applications one of the most important devices in NGN is a Softswitch - a programmable device that controls Voice over IP (VoIP) calls. It enables correct integration of different protocols within NGN. 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). However, the Softswitch as a term may be defined differently by the different equipment manufacturers and have somewhat different functions.

For next generation PSTN scale solution, the service providers must ensure that the following key requirements are met to provide equivalence with the PSTN. The Key requirement covers these elements which are Network Security, Quality of Service (QoS), Network Reliability, Migration path, OSS support, Billing System and Network Interconnection.[1]

One may quite often find the term Gatekeeper in NGN literature. This was originally 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. As soon as this kind of device started using the Media Gateway Control Protocol (and similars), the name was changed to Media Gateway Controller (MGC).

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

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

[edit] Implementations

In the UK another popular acronym was introduced by BT (British Telecom) as 21CN (21st Century Networks, sometimes mistakenly quoted as C21N) -- this is another loose term for NGN and denotes BT's initiative to deploy and operate NGN switches and networks in the period 2006-2008 (the aim being by 2008 BT to have only all-IP switches in their network)

The first company in the UK to roll out a NGN was THUS plc which started deployment back in 1999. THUS' NGN is comprised of 10,600km of fibre optic cable with more than 190 points of presence throughout the UK. The core optical network uses DWDM (Dense Wave Division Multiplexing) technology to provide scalability to many hundreds of gigabits per second of bandwidth, in line with growth demand. On top of this, the THUS backbone network uses MPLS technology to deliver the highest possible performance. IP/MPLS-based services carry voice, video and data traffic across a converged infrastructure, potentially allowing organisations to enjoy lower infrastructure costs, as well as added flexibility and functionality. Traffic can be prioritised with Classes of Service, coupled with Service Level Agreements (SLAs) that underpin quality of service performance guarantees. The THUS NGN accommodates seven Classes of Service, four of which are currently offered on MPLS IP VPN.

In the Netherlands, KPN is developing a NGN network in a network transformation program called all-IP -- this is another loose term for NGN that is increasingly used. Next Generation Networks also extends into the messaging domain and in Ireland, Openmind Networks has designed, built and deployed Traffic Control to handle the demands and requirements of all IP networks.

In Bulgaria, BTC (Bulgarian Telecommunications Company) has implemented the NGN as underlying network of its telco services on a large scale project in 2004. The inherent flexibility and scalability of the new core network approach resulted in an unprecedented rise of classical services deployment as POTS/ISDN, Centrex, ADSL, VPN, as well as implementation of higher bandwidths for the Metro and Long-distance Ethernet / VPN services, cross-national transits and WebTV/IPTV application.

[edit] See also

[edit] External links

[edit] References

  1. ^ "VoIP Next-Generation Network Overview". http://techviewz.org/2009/02/voip-next-generation-network-overview.html. Retrieved on 2009-02-12. 
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