Data Leaves Voice Standing Still
teledotcom.com
As data traffic surpasses voice, carriers turn
to new backbone technologies
By Rachael King. Rachael King is business editor for
tele.com. She can be reached over the Internet at
rking@cmp.com.
The migration of voice traffic from conventional
circuit-switched networks to packet-switched networks has
begun in earnest.
In a watershed announcement last month, Sprint Corp. said it
plans to carry all of its traffic-voice, video, and data-over its
asynchronous transfer mode (ATM) network. The approach
will cut the cost of delivering a voice call by 70 percent, said
Sprint CEO William T. Esrey.
Sprint is not alone in making the shift. AT&T, Frontier Corp.
(Rochester, N.Y.), IXC Communications Inc. (Austin, Texas),
Level 3 Communications Inc. (Omaha, Neb.), and Qwest
Communications International Inc. (Denver) count themselves
among the growing number of service providers planning to
ship voice traffic over their data networks.
Their reasoning is simple: If data traffic hasn't already
overtaken voice traffic on backbone networks, it will soon. So
it makes sense to use a backbone that is optimized to handle
data more efficiently than today's voice network, which is
based on circuit-switching and time-division multiplexing.
"We're rapidly migrating from being a voice network that also
carries data into a data network that also carries voice," Bell
Atlantic Corp. chief executive Ivan Seidenberg said last month
at the Supercomm '98 trade show. Bell Atlantic this month
plans to begin building what it calls a backbone voice-data
network, spending $200 million on the ATM project over the
next five years.
Ameritech Corp. chairman Richard Notebaert told the same
convention that his company is considering a similar move-if
more cautiously. "Packet switching with a high-quality voice
overlay soon will become a reality," he said. "And when it
does-that is, when the quality is at least equivalent to current
voice technology-we'll incorporate it into the 1,480 central
offices in our network. When that happens, the public
switched voice network will become the public switched data
network."
It's about money
The key factor behind the shift-the one that will account for
Sprint's 70 percent cost reduction in delivering a voice call
over a data network-is the performance/cost ratio of data
switches and routers versus conventional Class 4/5 central
office switches.
While many service providers agree that integrating all types of
traffic onto one data backbone makes sense, they don't all
agree on which data technology to deploy. Sprint, AT&T,
Frontier, and IXC favor a scheme of packetizing voice over an
ATM backbone. Level 3 and Qwest say they will instead use
packet switches and an Internet protocol over Synchronous
Optical Network (IP over Sonet) infrastructure.
Level 3 CEO James Q. Crowe outlined his company's
motivation for deploying an all-IP network during a
presentation in late May at Vortex 98, a conference for top
Internet and telephone industry executives. His reasoning all
came down to cost. Packet switching has a better
performance/cost ratio than ATM or conventional class 4/5
switches, Crowe said, and the difference is growing.
To support his claims, Crowe cited research by Peter Sevcik,
a senior associate at Northeast Consulting Resources Inc.
(Boston), who demonstrated that each successful new
generation of switching technology cuts the performance/cost
doubling time in half. That is, conventional central office
switches double their performance/cost ratio every 80 months,
according to Sevcik, while ATM switches do it in 40 months.
Even better, packet switches and routers double their
performance/cost ratio every 20 months, while frame switches
double their ratio every 10 months.
It is the prospect of quick improvements in packet technology
and its performance/cost ratio that has executives like Level 3
CEO James Crowe and Qwest CEO Joseph Nacchio building
next-generation IP over Sonet networks. "Don't ever bet
against compounding," says Crowe.
Sprint chief technology officer Martin J. Kaplan agrees there
are major benefits to moving away from the industry's
conventional class 4/5 central office switches. The
data-handling capabilities and efficiencies of ATM are such
that Sprint could simultaneously serve 100,000
videoconferencing customers from one ATM switch, he says.
The same load would take a half-dozen conventional switches,
he says.
Issues with management
Kaplan, however, favors an ATM infrastructure rather than IP
over Sonet. Carrying mission-critical voice and data traffic for
business and residential customers still requires a network that
is reliable and-most importantly-manageable, Kaplan says. IP
over Sonet cannot yet provide those kinds of capabilities for
the high traffic volumes that Sprint carries, he says.
Observers say Sprint is making a big bet on its new approach.
It is still unclear whether the company's new architecture is one
that will last for many years, they say, or whether it will turn
out to be merely a stepping stone to an entirely
non-circuit-switched architecture like IP over Sonet.
In the meantime, the fact that Level 3 and Qwest handle much
lower traffic volume than Sprint may make it easier for them to
deploy IP over Sonet networks, industry experts say. By the
time they reach the level where it becomes necessary to have
more sophisticated network and traffic management
capabilities, like those found in ATM, new management
systems may already be developed for IP over Sonet. In fact,
since Level 3's network won't be completely built for four to
six years, the say, the company can afford to look ahead and
gamble on a cost-effective next-generation network.
Whatever their choices, all of the service providers see the
need to act quickly. Underscoring the rapid pace the voice
migration would take, Notebaert pointed out that this year, for
the first time, fully half of Ameritech's traffic will be data
instead of voice. "The percentage will grow to something like
99 percent of all network traffic minutes by the year 2000," he
said.
"On a symbolic level, it represents what Intel's Andy Grove
calls a strategic inflection point-the moment where the
paradigm shifts and conventional wisdom ceases to apply,"
Notebaert said.
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Last Modified: 8-Jun-98
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