As convergence progresses at different rates at different parts of the
network, service providers risk creating disparate systems that support a
variety of access services and network protocols. When providers use
different access equipment for different services it results in higher costs
and lower reliability. The system administration and maintenance costs are
higher when different equipment must be supported for similar applications.
Additionally, providers often lose their equipment price negotiating clout
when they are forced to buy from different vendors to meet all of their
service needs. The goal is to converge voice and data for maximum top-down
advantages without creating different networks for each access service. A
new generation of access systems based on multi-application platforms are
providing a way to reduce the system's complexity by meeting the needs of
each converged market or segment with one single platform.
The business case for many converged markets, such as long-distance
wholesaling, makes goals such as uniform access equipment secondary
priorities. Another case of convergence that is causing service providers to
implement different sets of equipment for convergence is multi-service
access. A service provider that offers multi-service access and also offers
long-distance services, for example, has a compelling business case for
convergence. However, a provider that deploys both multi-service access and
long-distance services often ends up with fragmented networks. The
underlying questions that the multi-application approach answers are how
does a service provider deal with the fragmentation of each market and
service type that require different sets of equipment, and what does the
provider do with all of the access gateways for the different voice markets?
Ultimately, how can the network be simplified?
Convergence Of The Last Mile
As a somewhat new approach to offering a variety of services on a single
network, multi-service access is becoming more popular due to the ability to
add voice to DSL (VoDSL) or cable (VoCable) broadband data services,
allowing the service provider to become a full-service supplier. Because of
this, multi-service access is becoming a more attractive business for many
service providers due to the benefits that offering both voice and data
services provides, and the low barriers to entry. Whether a provider is
offering xDSL, cable, or fixed wireless broadband access, voice services can
be added. Voice is typically viewed as a new service that providers are
trying to deploy using their broadband data access service to tap the voice
market and become a competitive local exchange carrier (CLEC).
A good example of this is VoDSL for converged data and voice services to
businesses. Today this means voice and data are converged to offer local
phone services and broadband data services over a single connection. An
Integrated Access Device (IAD) is installed at the end user premise to
terminate the DSL modem connection and provide connectivity for phones and
Ethernet. The IAD digitizes and packetizes the voice connections typically
in VoATM format for transport over the DSL connection. A single to more than
a dozen or more (typical range of 1--16) phone lines can be supported
through the DSL link.
On the infrastructure side, the "last mile" to the subscriber
is terminated and split into data and voice streams. For voice services, a
voice gateway is needed to route the voice over the Internet or to the PSTN.
Voice and data are converged over the last-mile connection between the
subscriber and the central office but then are split as needed to allow
access to a full range of PSTN services. With this architecture, service
providers can offer the same services as the ILEC (incumbent local exchange
carrier) because the multi-service access provider will route the voice call
over the data network to reach the PSTN, making it fully transparent to the
end user. Alternatively, the service provider may offer a new service to
users by offering low-cost long-distance over data networks and providing
the voice connection over the data networks.
Many CLECs are rolling out converged access plans or multi-service plans
including SBC Communications Inc., which is leading in offering VoDSL among
the incumbents. Sprint is working with vendors to deploy VoDSL services by
year-end. AT&T's purchase of MediaOne so far has captured 39,500 users
for its voice-over-cable service, adding 500 per day and with a goal to have
400,000 to 500,000 by the end of 2000. VoDSL is slowly but surely becoming a
popular way of adding voice services over a data network. According to
Cahners In-Stat Group, the U.S. market for VoDSL is forecast to grow 25-fold
in 2000, from only about 2,400 subscribers and $47 million in service
revenues in 1999 to 61,000 subscribers, with service revenues of $1.2
billion, by the end of 2000.
The key is that by providing multi-service access, the service provider
can add additional revenue to their existing connection to the client that
requires a low investment to gain a new revenue stream. Multi-service access
is one business opportunity that could be a service provider's whole
business, or an added layer.
Implementing Multi-Application Platforms
Multi-application platforms are a solution to the complexity of having
to support convergence in different markets. Many multiservice access
systems use different technologies to support voice services than VoIP
access systems used in long-distance wholesaling. The typical
multi-application platform, which can include a gateway using a
multi-application platform architecture, typically uses a digital signal
processor (DSP), which is able to run different protocols to support several
types of services. For example, the multi-application gateway could support
VoDSL for multiservice access and support VoIP for long-distance wholesaling
access. The platform must be flexible because there are differing standards
for voice access depending on the data network connection for VoDSL, VoCable,
VoATM, VoIP, where each is connecting to the PSTN and different standards
are required for each connection.
In general, what's driving the rapid proliferation of the Internet is the
service provider's ability to integrate networks and services in new ways,
based on these new standards and protocols available. Mixing up different
services and offering different applications creates the complexity of
having to purchase, integrate, and maintain different sets of equipment or
duplicate sets of equipment. Multi-application platforms reduce the
diversity of equipment and simplify the overall design, saving time, capital
expenditures, and operating expenses. Having a single technology-type for
both voice and data that is flexible and programmable, is also important
when adding new features, applications, and upgrading the system to support
A platform should be chosen so that it can run multiple applications.
The service provider should consider all of the near-term application needs
as well as long-term potential services. The multi-application platform
chosen must support all of the near-term applications and have the capacity
to meet future needs, such as more capacity and new services. However, since
it is difficult to predict future needs in the rapidly changing networking
market, the capacity and flexibility, such as the ability of each DSP core
to run independent applications, should be a key metric in choosing the
platform. Choosing the right platform will deliver flexibility and lower
cost of ownership.
Next month, I will take an even closer look at the VoIP gateway and then
examine the elements of the gateway -- both hardware and software and what
some of the issues are relating to quality, density, and interoperability.
Scot Robertson is the
product line manager for Remote Access Products at Analog Devices, Inc., a
leading manufacturer of precision high-performance integrated circuits used
in analog and digital signal processing applications.
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