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Special Focus
June 2001


Voice Over IP Over Glass: Long Overdue


The advent of voice over IP (VoIP) and advances in fiber optic communications combine to represent a major opportunity for system vendors and service providers alike. As long-haul bandwidth has grown recently, fueled by exuberant investments in optical networks, focus is now turning to metropolitan area networks (MANs) and converged services. Fiber optics in MANs is enabling the concept of "wide area LANs," which could be the springboard for huge growth in distributed hosted services. VoIP promises to be one of the dominant applications utilizing this model. The enormity of the opportunity was revealed in a Probe Research study predicting the global Voice Over Packet service revenues would reach $15 billion by 2005. This article examines the three functional areas that demand the most attention by service providers when deploying converged services in a world of abundant bandwidth: Infrastructure optimization; managed cost models; and network management and control. Making the right decisions in these three areas holds the promise of creating a completely new way of viewing how telecommunications services are deployed, consumed, and managed.

Optimizing Infrastructure
Like the grand unification theory in physics, service providers have always understood the value of a converged communications infrastructure. In a way, some form of convergence has always existed. Both the new, improved digital PSTN and its fully analog predecessor were optimized for voice. The PSTN continues to carry most private enterprise network traffic through leased lines and dial-up connections. Frame relay, by contrast, was optimized for data traffic, but also handles voice for some enterprises. Asynchronous transfer mode (ATM) was designed as a fully converged architecture with the transformation of both circuits (voice) and packets (data) into cells.

Advances in technology have brought a new and more promising perspective to the topic of convergence. Fiber optics and dense wave division multiplexing (DWDM) have made bandwidth fairly abundant, albeit not yet fully optimized. Ethernet is now expanding beyond the boundaries of the traditional LAN with the advent of gigabit data rates. Transparent LAN services are now available in MANs, and equivalent bandwidths are becoming available in WANs. Similarly, IP now dominates at the network layer to the virtual exclusion of all other previous contenders.

The consolidation to fewer, yet more capable technologies, and the availability of more cost-effective fiber optic bandwidth combine to make it more feasible than ever to converge voice and data services. And this is exactly what is occurring in the industry.

The rapid growth of media gateway deployment means VoIP is becoming ready for prime time with a fairly robust set of industry standards and enhancements to quality of service (QoS) end-to-end in the public network infrastructure. Trials have been so successful in fact, that many service providers are accelerating their rollout plans.

VoIP is significant because it enjoys enormous synergy with data communications applications. A common protocol with a common, bandwidth-rich infrastructure affords numerous advantages to service providers and subscribers alike, and presents lucrative opportunities for new "mixed" or multimedia services that were previously impractical -- or impossible. Indeed, the secret to success in the converged broadband communications era will be to put the "service" back into "service provider" with value-added capabilities that afford tremendous competitive differentiation.

Managing Costs
Next-generation converged networks promise orders of magnitude increases in communication capacity with a corresponding decrease in delivery costs. A well-designed infrastructure should be able to cut operating costs in half -- or more.

The best way to control costs while migrating to a converged infrastructure is to maintain compatibility with existing systems and services. This is especially important for the incumbent LECs, who need to protect substantial investments, but also applies to the so-called "greenfield" operators, like competitive, data, and building LECs, who need to integrate seamlessly with the configurations of customers and other carriers.

Consider the traditional telephone handsets and PBX systems. Everyone has a phone -- and most big companies use PBXs. Consumers and businesses depend on these devices daily. For this reason, a major obstacle to VoIP has been the requirement to replace existing equipment with special IP phones or PC-based software. The right VoIP solution, instead, will need to be 100 percent transparent to existing telephone equipment. The phone should plug into the same jack, which should continue to provide power even when the lights go out. Such a real-world solution is essential because it ensures that the transition will occur in a way that is totally transparent to users.

Cost-saving compatibilities also exist at just about every other segment in an end-to-end connection. Today virtually every home and business in the industrialized world is served by local loop wiring. So the right converged services solution would be able to leverage this valuable resource by carrying one or more phone calls and data traffic together at a broadband data rate. Specially designed voice/data routers (VDRs) and integrated access devices (IADs) are now available precisely for this purpose. The VDR, for example, has interfaces for the LAN as well as a PBX (via an FXS or T1/CAS port) or individual telephones (via multiple analog POTS ports). Some VDRs even have a back-up POTS port if needed. And although digital subscriber lines have suffered some setbacks recently, DSL's ability to bring broadband to the ubiquitous local loop makes this technology an indispensable element of converged communications.

Once in the central office, cost-saving compatibility means supplementing the super-expensive Class 5 switches in a way that caps investment in these behemoths -- and eventually permits their replacement. For example, IP Centrex technology allows this value-added, feature-rich service to be implemented in software on ordinary application servers. These and other application servers, along with media gateways and softswitches, are now available with feature sets that exceed the potential of any Class 5 switch -- at a fraction of the cost. The more powerful and profitable converged architecture also facilitates the "Decentral Office" where many customers in a single building -- a multi-tenant unit (MTU) office or apartment, for example -- enter the public "cloud" directly from the private premises.

The backbone also presents cost-saving opportunities. With transparent, QoS-enabled Ethernet LAN services in the MAN, all voice and data traffic can be integrated at the premises transparently, efficiently, and cost-effectively. Long-distance services in the WAN -- whether for voice or for data -- have already experienced the many benefits of convergence using IP and ATM. Convergence not only eliminates the need for parallel backbones, it presents many opportunities -- if not a whole new perspective -- for enhanced services, like integrated messaging and collaborative work.

Improving Control
Convergence, with its many cost-saving advancements, affords a new, improved scenario for managing public and private networks. With the "intelligence" increasingly in server-based software, provisioning will be possible on-demand -- and without a costly truck roll. Naturally, this will require true plug-and-play customer premises equipment, and at least a few vendors have figured out how to make such simplicity a reality with auto-configuring systems.

A converged network infrastructure eliminates all parallel systems and segments -- except those required for redundancy -- thereby reducing the overall complexity of the network. In an all-IP network, SNMP creates a common denominator that further reduces management complexity. This in turn reduces the number of platforms and applications required in the network operations center, which translates into smaller staffs and less training to achieve the same carrier-class results.

Finally, convergence allows carriers to manage bandwidth better by exploiting the fundamental differences between data and voice communications. Data needs speed, but is quite forgiving of network imperfections. By comparison, voice demands miniscule amounts of bandwidth, but is intolerant of delay. Policy-based control, complete with traffic shaping, makes this task not only possible, but also quite straightforward. CPE is now available with integral digital signal processors that report mean opinion score (MOS) measurements and other parameters, making it easy to enforce Service Level Agreements (SLAs) and manage voice quality end-to-end on a per-call basis.

A Whole New World
The combination of fiber optics, both in the backbone and extending to the subscriber facilities, and converged voice and data services, such as VoIP, is creating a whole new world. And in this new converged world, the formula for service provider profitability is more favorable than ever before: Greater potential for value-added services that can be delivered at a significantly lower cost. Ten years from now, the PSTN as we know it will be a thing of the past. Indeed, the first-to-market advantage enjoyed by some of today's leading-edge service providers is likely to serve them well into the future. 

Jim Zeitlin is chief technical officer at Vpacket Communications. Vpacket is a privately held company based in Silicon Valley specializing in converged voice/data broadband solutions for LECs and other service providers. 

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