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
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
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
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
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
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
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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