Building Optimal NGN Expansion Using Leading
Executive Summary Telecommunications industry standardization, device interoperability, and network compatibility play important roles in promoting innovation and competition in the Next Generation Networks (NGN) voice and multimedia switching infrastructure, also known as Voice over IP (VoIP). VoIP is intended to deliver a full range of cost-effective telephony, multimedia, and innovative value-added services, while reducing total cost-of-ownership and time-to-market for services, and increasing business opportunities. One of the notable elements of the NGN expansion is the VoIP media gateway, providing the bridge between today s TDM-based legacy network and the next-generation services infrastructure. For service operators, NGN expansion (or even replacing old media gateways, like end-of-lifed media gateways), can present them with several options: continue deploying the same trunking media gateway brand they have been using, or selecting an advanced technology solution fully interoperable second-source trunking media gateways. For an advanced technology, cost-effective, and reliable second-source VoIP trunking media gateway solution, service providers can look to the interoperable, field-proven Dialogic I-Gate 4000 Media Gateways product line. The benefits of these products for service operators include highly reliable, cost-effective and scalable platforms, exceptional voice quality and bandwidth savings, high quality fax over IP services, and in-house DSP technologies. 2
Table of Contents Introduction............................................................................4 Next Generation Voice Switching and Bandwidth Optimization Infrastructure...........................4 VoIP Media Gateways.....................................................................6 Single-Vendor Media Gateway Offerings..................................................6 Offerings................................................6 Dialogic I-Gate 4000 Media Gateways Snapshot.............................................6 Interoperability for Seamless Deployments.................................................7 Notable Voice Quality................................................................7 Bandwidth and Router Savings.........................................................8 Fax and T.38 Expertise...............................................................8 VoIP over TDM Transmission Infrastructure................................................8 Scalability.........................................................................8 3
Introduction In today s technology-driven world with its multimedia applications, triple-play bundle services, and innovative business models telecommunications industry standardization, device interoperability, and network compatibility play important roles in promoting innovation and competition in the Next Generation Networks (NGN) voice and multimedia switching infrastructure, also known as Voice over IP (VoIP). Having had its beginnings in the late 90s primarily as a means for reducing the cost of long-distance and international calls, VoIP use has expanded to include the core network and the access network; and it is now regularly used by residential subscribers as well as in the enterprise. VoIP is the focal point for new deployments and is being widely used for legacy TDM-based PSTN and 2G mobile switching infrastructure replacement and/or in connection with expansion of the growing number of VoIP networks. And trunking media gateways continue to be deployed for connecting with the huge worldwide-installed base of PSTN and 2G mobile switches. When expanding networks or replacing old media gateways (for example, media gateways with announced end-of-life), service providers can choose from options that include: continuing to deploy the same trunking media gateway brand, or selecting fully interoperable second-source trunking media gateways solution. This application note focuses on the NGN s fully interoperable second-source trunking media gateways solution, as well as the benefits offered in selecting this NGN implementation approach. Also presented is the Dialogic I-Gate 4000 Media Gateways product line, a VoIP trunking media gateway product line that resulted from years of work focused on internetworking protocols support, statistical multiplexing, voice analysis, toll-quality voice compression, fax and modem demodulation, traffic congestion handling, error concealment, echo cancellation, and reliable signaling optimization. Next Generation Voice Switching and Bandwidth Optimization Infrastructure The Next Generation Network (NGN) voice and bandwidth optimization switching infrastructure, also known as Voice over IP (VoIP), is intended to deliver the full range of cost-effective telephony, multimedia, and innovative value-added services, while reducing total cost-of-ownership and time-to-market for services, and increasing business opportunities. VoIP also improves the telecom operator s ability to scale investment in telecom infrastructure in order to respond to market demand and minimize risks. Whether planning to expand an existing network or building a greenfield infrastructure, telecom operators view the three-layered switch architecture reference model as a preferred alternative to the historical hierarchical and monolithic circuit-switching infrastructure that has dominated the telephony industry for more than a century. The three-layered switch model defines a layered switch as one that is built from interoperable components residing in: A media adaptation layer (including media gateways and access devices) A call control and signaling layer (including softswitches and signaling gateways) A service layer (including application and feature servers) The three-layered switch model approach, and a rich standardization within and between layers, gives telecom operators the flexibility to select the notable next-generation component(s) for each of the three architectural layers. Figure 1 is an example of a three-layer switch model. 4
Service Layer IN OSS Application Server Billing Control Layer INAP SNMP SNMP Radius/FTP Diameter Signaling Gateway Softswitch SIP-I/SIP/H.323 Other Operators VoIP Peering Networks Media Layer H.248/MGCP IUA/M3UA H.248/MGCP IUA/M3UA TDM Interface RTP/RTCP TDM Interface PSTN or MSC Switch Trunking Media Gateway Trunking Media Gateway PSTN or MSC Switch Figure 1. Three-Layer Switch Model The next-generation switching infrastructure has become a preferred alternative for cap-and-grow expansion and/or replacement of existing networks (for example, PSTN switch substitution), and for implementation of the greenfield networks; and is likely to displace the existing legacy telephony infrastructure at the end of its service life. In addition to the switching network paradigm evolution, the media adaptation layer s component features allow for further CAPEX and OPEX savings due to bandwidth-saving and network-optimizing mechanisms. A significant requirement is that the next-generation voice switching and bandwidth optimization infrastructure components and solutions be designed such that there is Total Service Transparency for the call signals and services. This requires that the services currently offered by the legacy TDM-based network (such as voice, fax, modem, Intelligent Network (IN), and video conference) be maintained and guaranteed by the VoIP infrastructure with the quality and reliability that end-users are accustomed to and have come to expect. One of the fundamental elements of the next-generation telecom scenario is the VoIP media gateway, providing a bridge between today s TDMbased legacy network and the next-generation services infrastructure. VoIP media gateways are called upon to simultaneously execute the following tasks: Perform media processing, including voice encoding silence suppression, echo cancellation, network impairment concealment, signaling handling, plus others Perform inter-media network adaptation between the various circuit-switching and packet-switching network domains Provide a multiple-media switching platform for the various service and signaling payloads according to required routing scenarios (for example, TDM-to-TDM and TDM-to-IP) 5
VoIP Media Gateways Single-Vendor Media Gateway Offerings Although the NGN model being discussed, which includes multiple functional elements interconnected through standardized interfaces, allows telecom operators to select a leading solution for each NGN network component, many service providers adopt, for their first NGN deployment, a single-vendor vertical-solution approach. Adopting this approach is a strategic step because NGN infrastructure has complex deployment and operational processes, requiring the minimization of risk and deployment cycles. Since the softswitch is the heart of the NGN and the most complex component, initial planning decisions of service providers building new NGNs are mainly focused on the softswitch components. As a result, service providers generally selected their NGN vendor based for the most part on a softswitch evaluation. In this decision process, the trunking media gateways that were chosen often ended up being those offered by the same softswitch vendor. Vertical-solution vendors offer trunking media gateways belonging to one of the following two categories: The trunking media gateway portfolio is built using OEM components, and consequently the vendor lacks ownership and control over the technologies, product roadmap, and life cycle The vertical-solution vendors allocate their main R&D expertise and resources to the softswitch and application server components, and develop their own media gateway as a complementary product line In either case, the typical result is a trunking media gateway with weak performance and notable quality limitations. Offerings Although the offerings noted above characterize the initial NGN deployments, current NGN deployments and expansion of existing NGNs present service providers with the opportunity to enhance and optimize the VoIP media gateway infrastructure by adopting leading, interoperable second-source media gateways. Using this approach service providers are able to: Leverage the NGN infrastructure investment by deploying VoIP media gateways that provide high quality services and performance Enhance their competitiveness by building network solutions with minimal OPEX Select the most cost-effective solution alternative Start with state-of the-art, industry-leading media gateway product lines rather than settle for inferior options Compare vendors so as to realize improvements and better customer support, with a focus on technological/business issues Engage directly with the VoIP media gateway manufacturer, which owns the technology and product roadmap Use different vendors to avoid relying on just one vendor s technology, financial stability, and performance Dialogic I-Gate 4000 Media Gateways Snapshot Dialogic offers its I-Gate 4000 Media Gateways product line, which leverages edge platform and Digital Signal Processing (DSP) technologies and provides a desirable solution for second-source VoIP trunking media gateway applications. The I-Gate 4000 Media Gateways have features that can benefit providers who are replacing and/or expanding the VoIP media gateways in their network. I-Gate 4000 Media Gateways, which simultaneously deliver high voice quality and allow high bandwidth savings, provide recognized VoIP trunking media gateway solutions that support standardized interfaces and protocols. 6
Designed to address the functional and operational needs of service providers and carriers, the I-Gate 4000 Media Gateway product line includes models that cover the range of service applications and deployment port densities which usually are considered by vendors when evaluating second-source media gateways: Dialogic I-Gate 4000 PRO Media Gateway For mid- and high-port-density applications (thousands of ports). Supports E1, T1, DS3, STM1, OC-3, and mixed TDM trunk links. Dialogic I-Gate 4000 EDGE Media Gateway More compact solution for small-port-density applications (up to 500 ports). Supports E1 and T1 TDM trunk links. Both the I-Gate EDGE and I-Gate PRO Gateways are implemented using the same core technologies, and they are built on a highly reliable and redundant platform architecture that allow 99.9999% ( six 9s ) availability. The I-Gate 4000 Media Gateways high availability features include: Redundancy for the traffic-affecting modules Non-traffic-affecting (hitless) redundancy switchover Link redundancy features (TDM links, Gigabit Ethernet and fast Ethernet links) Softswitch redundancy Non-traffic-affecting hardware and software upgrade Can upgrade online without interrupting revenue-generating traffic Hot-swappable and field-replaceable modules Can be inserted/extracted without switching off the system and without impacting the traffic carried by other modules Uncompromised stability Designed to handle the full load and call completion rate as specified, without loss of performance or impact on service quality. Interoperability for Seamless Deployments Operators planning to deploy next-generation telephony network second-source solutions are focused on guaranteeing quality of services in multi-operator and multi-vendor market environments. I Gate 4000 Media Gateways are open and standards-based VoIP media gateways designed to provide full interoperability in new generation switching infrastructure scenarios, facilitating smooth integration with other vendors network components and seamless interconnection with other operators networks. These features thus allow operators to smoothly interconnect I Gate 4000 Media Gateways to operating networks based on existing or emerging standards without disrupting service and having undesirable islands of capability. Notable Voice Quality I-Gate 4000 Media Gateways are designed to offer higher voice quality that is unparalleled among comparable products. Dialogic products represent the effort of some of the most experienced vendors in statistical voice multiplexing equipment, and have been field-proven their ability to deliver Toll Quality bandwidth-optimized telephony and signaling traffic with its carrier-class bandwidth-savings systems operating in hundreds of networks worldwide. Dialogic s signal processing techniques and codecs are known for their spectral transparency and stability under the even severe traffic and network conditions. Other beneficial techniques include state-of-the art echo cancellation, high performance silence suppression and jitter buffer algorithm, smart packet loss concealment, and packet priority selection. 7
Bandwidth and Router Savings Despite trends toward plunging costs of bandwidth resources, many transmission network segments still command high prices, and/or available transmission bandwidth is limited. For telecom operators deploying or upgrading a network of trunking VoIP media gateways, the I-Gate 4000 Media Gateways product line allows for a reduction in the bandwidth requirements and in the payload rate of the VoIP sessions carried through the IP network, while maintaining the quality and reliability levels of the transported calls. The I-Gate 4000 Media Gateways product line provides an unmatched solution overall, enabling substantial savings on equipment and operations, highly efficient use of the deployed network resources, and new broad opportunities for competitiveness and revenue. Fax and T.38 Expertise Fax performance and reliability remains a critical issue for VoIP networks. Fax traffic still comprises a significant percentage of telephone calls, and this is expected to continue for at least the foreseeable future. Accordingly, deployment of a network infrastructure inconsistent with today s fax handling methods could pose ongoing operational issues and customer dissatisfaction. Being able to provide fax interoperability between different vendors is an achievement because many VoIP service providers face a multitude of fax issues when trying to run VoIP among different vendors. This leads to network operators trying to bypass fax interworking by using Fax Passthrough, which can present reliability and bandwidth issues in the networks, or changing their network planning to avoid interworking among different vendors. Dialogic products reflect years of fax interoperability experience with many leading vendors, and are able to address fax issues quickly and reliably. Notably, I Gate 4000 Media Gateways allow seamless integration of fax over VoIP networks. VoIP over TDM Transmission Infrastructure Those who are deploying VoIP networks using TDM transmission infrastructure can look for further CAPEX and OPEX savings with the I-Gate 4000 Media Gateways, which also support IP over TDM links. For applications using a TDM transmission infrastructure, the I-Gate 4000 Media Gateways can be directly connected to E1, T1, DS3, STM1, and/or OC-3 links to carry the VoIP, signaling (MGCP or H.248), and management traffic. Scalability The I-Gate 4000 PRO Gateway and I-Gate EDGE Media Gateway are designed to cover the range of media gateway site sizes with minimal investment in the initial deployment stage, while allowing for smooth, gradual capacity expansion (and associated investment requirements) as traffic demand and/or network footprint grows. Deployed I-Gate 4000 PRO Gateway terminals can be expanded by installing additional DSP and TDM interface modules without affecting the traffic carried by the currently operating modules. Deployed I-Gate 4000 EDGE Media Gateway terminals can be expanded by provisioning additional capacity licenses, without affecting the traffic carried by the terminal. 8
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