NGN Technology – A overview 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[2].
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 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. 23 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 Soft switch – 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 Soft switch is creating the interface to the existing telephone network, PSTN, through Signalling Gateways (SG) and Media Gateways (MG).
However, the Soft switch as a term may be defined differently by the different equipment manufacturers and have somewhat different functions. 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). We are presently using PSTN which is mainly circuit switching based network and it is divided into an hierarchical architecture viz. ? Level –I TAX exchanges, ? Level-II exchanges and then Tandem/local exchanges. The PSTN network is mainly optimized for voice calls and not much suited for data services. We have a separate network for data services. Today the world over trend is for a single converged network used for all type of services viz. voice, data, video which is called Next Generation Network and is a packet switching based network. To change over from current generation network to next generation network we have to move in a step-by-step manner to safeguard our existing network infrastructure and investment and therefore we have to follow an evolutionary path. IP TAX is the first step towards the Evolution of Current Generation Network to Next generation Network”. In other words IP TAX is the replacement of existing Level –I TAX exchanges to IP based network (Packet switching network) and rest all the network still remaining circuit switched network. The other reasons why we should evolve our existing network to NGN are that the existing circuit switched networks have following problems: • Slow to develop new features and capabilities. • Expensive upgrades and operating expenses. • Proprietary vendor troubles Large power and cooling requirements. • Limited migration strategy to New tech. • Model obsolescence. Key Principles of NGN Open architecture : open to support service creation, service updating, and incorporation of service logic provision by third parties and also support “Distributed control” as well as enhanced security and protection. Independent provisioning : service provision process should be separated from network operation by using distributed, open control mechanism to promote competition. Multiplicity : The NGN functional architecture shall offer he configuration flexibility needed to support multiple access technologies. ITU-T NGN is Not But Next Generation Internet Net. Next Generation Public Telecommunication The IMS based network IMS is a key part of NGN Any more best duties Guaranteed duties Only for a Fixed nor a Mobile network Converged capabilities btw Fixed- Mobile (FMC) Any more closed public networkFully open I/F in access- core and service-transport only for usage awareness Support various businesses Key features of NGN NGN; a Convergence Platform #
Combination IP with Broadband accelerating intrinsic convergence •Service convergence: Web based service provisioning •Network convergence: IP over any broadband transport networks * Advanced Mobile and Wireless technology initiate business convergence such as Fixed-Mobile convergence * Broadband Fixed, Wireless and Mobile technology boost another business convergence, called “Multiple Play: Tele-Broadcasting” |Telebroadcasting | | FMC | |NGN | # NGN :Enablers for convergence •Simple linkage btw layers N •Simple linkage btw layers with dynamics Simple business relationships G •Diverse and Flexible business relationships •Simple players N •Diverse business models and players # Why we need NGN GSI ? The need to have a visible focus for the NGN work and to maintain the co-location of the closely related NGN work The ongoing work will be done by the Study Groups, meeting together according to an NGN work plan coordinated by SG13underthe banner of the NGN Global Standards Initiative (NGN-GSI)* NGN Multimedia Services •Realtime Conversationalce • Messaging, e. . IM, SMS,MMS • Push to talk over NGN •Point-to-Point interactive multimedia •Collaborative interactive communication •Content delivery •Push-based services •Broadcast Services (ie. Multicast) •Hosted and transit services for enterprises (IP Centrex, etc. ) •Informaion services •Location-based services •Presence and general notification services DATA Communication services •Virtual Private Network (VPN) •Existing data services •Data retrieval services •Online services •Sensor Network services •Remote control/tele-action services Public Interest Aspects Emergency Communications (including support of Early Warning) •Support for users with disabilities •Lawful Interception •Serveunbundling •Number portability •Network or Service provider selection •Prevention of unsolicited bulk telecommunications •Malicious communication identification •User identifier presentation and privacy ETSI TISPAN Release 1 Services Multimedia Telephony with PSTN/ISDN Supplementary Services Messaging Video telephony over NGN Presence Service ETSI TISPAN NGN Release 2 Enhancements to existing capabilities * IPTV *Transport stratum impact * DVB IPTV service Service stratum inter working •IMS-based IPTV * Fixed Mobile Convergence •CS Mobile voice service and WiFi with public residential VoIP service •CS Mobile voice service and WiFi with IP centrex service •CS Mobile voice service and WiFi with IP PBX •PS Mobile voice service and WiFi with public residential VoIP service •Use case for Voice Continuity •Roaming and handover scenarios Future Services *e-Health *e-Education *e-Commerce *e-Security e-Government Not just a new voice network ———————– SDH Transport with Overlay packets for data Common IP MPLS Transport pic] Gateways IP/MPLS Call Server Call Control Switching Interfaces ISUP/SCTP SG ANNOUNCEMENT SERVER Bearer Channels PSTN H. 248 NTP SERVER IP/RTP MG CORE IP BACKBONENETWORK Bearer Channels MG H. 248 SS7 SS7 STP ISUP/SCTP SIP-T Softswitch (MGC) Softswitch (MGC) SG NMS ANNOUNCEMENT SERVER Q. 1912. 5 PSTN SS7 SS7 STP SG EMS AS Soft switch (MGC) MG NGP CK MG RJ AM AG MG MG MG MG MG MG MG MG New Delhi KOL BPL MBI BG HYD CHN CBT ENK Chennai BSNL’s MPLS Core Existing STP N/w 0 PT LW MG MG MG JLN MG Existing STP N/w MG MG ND MG GU MG JPR as MG RPR AHM MG SG EMS AS Soft switch (MGC)
