Sprint Corp. last week trumpeted a vision long on claims
but short on details as to how it would enter the local business- and residential-access
markets using technology that eliminates traditional switching requirements.
Charging that today's mix of multiprotocol voice and data
networks "is a mess," Sprint chairman and CEO William Esrey said his company
would deploy a "revolutionary new set of technology advances" to deliver
services "that will change how homes and businesses communicate."
But he and other Sprint executives, as well as their
suppliers, left unclear how their approach differs significantly from those of many other
carriers that are looking at the same service opportunities. Sprint said it will rely
heavily on wide-scale use of unbundled telco lines to carry ADSL
(asymmetrical-digital-subscriber-line) services.
Later this year, Esrey said, Sprint will begin offering to
large business customers a full suite of broadband services based on the carrier's
"Integrated On-Demand Network" (ION). Sprint will use customer-premises gateways
supplied by Cisco Systems Inc. to combine voice and data signals into a single-cell-based
ATM (asynchronous-transfer-mode) stream for transport over the local fiber, ADSL or
wireless link, depending on which facilities Sprint chooses to use at a given location.
This approach, by putting voice calls into data format at
the premises, allows the carrier to use a new type of wide-area ATM-edge switch from Cisco
to interface with its regional and long-haul backbones without passing through traditional
circuit switches.
The new edge switches are among several components that
Cisco introduced last week to support carrier-class delivery of IP (Internet-protocol)
services, as well as all of the other types of service that are typically formatted into
the 53-byte cell framework used in ATM switches.
While Sprint is the first carrier to announce a commitment
to commercial use of the equipment, other Cisco customers, including U S West
Communications and GTE Corp., are giving it a hard look.
"U S West is very interested in the Cisco MGX 8800
wide-area switch, given its high-speed architecture and the wide variety of interfaces
supported," said Wayne Roiger, principal network architect for U S West Interprise
Networking, which is in the process of launching ADSL services in major markets throughout
the carrier's operating territories. "We plan to test it as soon as possible."
GTE is looking at the architecture, as well, noted Steven
Blumenthal, vice president and general manager of GTE Internetworking's infrastructure
group, which is evolving its data network to an all-IP architecture that will eventually
be used to carry voice, as well as data signals.
"We've been working pretty closely with Cisco to
understand the technology," he said. "Our goal is to deploy it in some standard
form."
The Cisco technology that integrates ATM and IP, known as
"tag switching," is the foundation for an emerging standard, MPLS (multiprotocol
layer switching), which eliminates much of the processing of packet-header information in
both routers and ATM switches.
The new edge switch represents a new level of integration
between ATM and IP, going beyond previous Cisco implementations of tag switching to better
exploit the directory intelligence within the IP domain, said Kevin DeNuccio, vice
president of service-provider operations at Cisco.
"We use the IP intelligence layer to create a
directory-enabled network that recognizes who the end-users are and what services they are
authorized to receive," DeNuccio said, explaining how the Sprint implementation will
work. "The terminology distinguishing ATM from IP is getting cloudy as we move to
this new level of integration."
Indeed, that cloudiness showed up in Sprint's press
presentation covering the bandwidth-on-demand capabilities of its new network, especially
as it applies to residential services, which, the carrier said, it will begin offering in
the second half of 1999.
A video clip depicting a family's use of the
"unlimited bandwidth" of the all-ATM network showed how the network would
allocate the throughput necessary to accommodate whatever level of phone and personal
computer usage is in play at a given moment, suggesting that voice calls would be mixed in
with the ATM data feed over the ADSL link.
But ADSL systems, such as what Cisco is supplying to
Sprint, are designed to carry circuit-switched POTS (plain old telephone service) over the
same line with the ATM data flow, avoiding the costly process of converting telephony
signals at the premises to the ATM format.
When asked how this division between voice and data squared
with the vision of flexible bandwidth assignment for all services, including voice, over
the ATM-access link, Sprint officials said their approach envisions putting the voice on
the ATM channel at the customer premises.
However, DeNuccio said, such integration might be
cost-effective in the enterprise environment, where multiple voice lines feeding a PBX
(private-branch exchange) are combined with data at the ATM gateway. But, he added, the
preferred approach on the residential side will be to packetize voice circuits at a
central point using an IP voice-gateway server, which can then feed the edge switch with
IP voice packets for connection into the Sprint broadband metropolitan-area network.
"My take at the high level is that this is a
significant migration from the circuit switch to packet-based implementation of IP at the
edge of the network," DeNuccio said.
In stressing the importance of ATM as the controlling
factor in setting quality of service and other parameters for all signals, including
voice, Sprint executives appeared to dispute the advantages of directly feeding IP signals
into SONET (synchronous optical network) links from high-speed routers. This was advocated
in a recent presentation at the Networld+Interop conference in Las Vegas by Vab Goel,
principal network-design engineer at Sprint's Internet-engineering unit.
"Packet over SONET scales from 155 megabits [per
second] to 2.4 gigabits [per second]," Goel said. "Two or three years ago,
people thought that in order to move data that fast, you needed ATM or gigabit Ethernet,
but that's no longer true."
The new Cisco edge switch is designed to support input and
output in either IP or ATM format, so that, if Sprint wants to, it can take the IP voice
packets from the IP voice-gateway server and directly feed them into SONET, rather than
first converting them to ATM, thereby saving bandwidth, along the lines advocated by Goel,
DeNuccio said.
When asked at the press conference whether Sprint would
follow this IP-over-SONET track with voice and other signals that are packetized to the IP
format, Kevin Bauer, president of Sprint's national-integrated-services unit, replied,
"That's getting beyond my area of technical expertise."
Such uncertainties surrounding the fundamentals of the
architecture to be deployed in the ION contrasted with Sprint's assertions that its
network would be uniquely effective in its ability to allocate whatever amount of
bandwidth is required for meeting customer needs on a moment-by-moment basis.
Sprint president and chief operating officer Ron LeMay said
this dynamic bandwidth-allocation capability -- combined with new network-management
efficiencies stemming from the use of proprietary software jointly developed by Bell
Communications Research and Sprint -- will cut the costs of delivering a voice call by 70
percent and the costs of provisioning new customers with all types of services by 60
percent to 80 percent.
But the costs of delivering the service when residential
service gets under way in the second half of 1999 will be such that Sprint will only be
able to target the 16 million or so households that are paying $110 per month or more for
combined communications services, LeMay said.
"We can deliver services in these price ranges,"
he added, declining to be more specific on pricing strategy.
Sprint officials asserted that the carrier would use
"splitterless" ADSL -- a plug-and-play version of the technology, topping out at
1.5 mbps -- to support consumer services. That leaves uncertain where it would find the
bandwidth to add video-on-demand entertainment to the service profile, although Sprint
said this would be part of the product mix.
Bellcore vice president and general manager John Boese
noted that the ADSL technology can be used at full strength to deliver signals at 7 mbps,
thereby accommodating video entertainment. But, he added, full-rate ADSL requires
installation of a second line in the home, in most cases, and it is not deliverable over a
much larger percentage of standard lines than is the case with splitterless ADSL, also
known as "ADSL.Lite."
The software that will run the ION is still under
development at Bellcore, Boese said. "We're not ready to discuss the details of how
the system works," he added.
Sprint is the third of the top three long-distance carriers
to announce plans for getting into the local-access business on a massive scale. So far,
AT&T Corp. and MCI Communications Corp. -- which, like Sprint, have CLEC operations in
place in some areas -- have failed to deliver on promises to move to wider-scale offerings
into the small-business and residential markets, although they continue to tout such plans
as key strategic goals.
"No company has been able to offer a complete
[broadband-access] strategy, until now," Esrey said. "This truly is the big bang
that expands the universe of what telecommunications can do in our homes and
businesses."
