Broadband Networking News
June 9, 1998 (Vol. 8, No. 12)
ASCEND AIMS TO REPLACE SONET WITH DIRECT ATM SWITCHING
Ascend Communications [ASND] yesterday (6/8) unveiled a new way
to build multiservice networks that integrate frame relay, ATM, IP
data with leased line and voice services by using its flagship GX 550
ATM core switch that now has the capability to switch directly to
dense wavelength division multiplexing equipment (DWDM) at OC-48/STM-
16 rates (2.5 Gbps). Ascend made its announcement at Supercomm '98 in
Atlanta.
Ascend claims that service providers will be able use the GX 550
ATM core switch to eliminate costly transmission equipment such as
SONET/SDH add/drop multiplexers and digital cross-connect systems.
"Our strategy for building core data networks based on ATM is to use
the GX 550 to go deeper into the core network and eliminate the need
for SONET and digital cross-connect hardware. In this way, private
line and voice traffic becomes just an application on the data
network," says Jeffery Kiel, director of product marketing at Ascend.
...Changing Core Network Architectures
Service provider core networks generally are composed of three
separate networks with three distinct functions, Kiel explains. The
data switching networks typically handles IP, ATM, or frame relay
traffic. A second layer, the transmission network, multiplexes and
grooms traditional voice and private line traffic, while adding
network protection capabilities. Finally, the optical network acts as
the physical networking layer that actually moves the traffic. "Each
network is built separately, and managed separately - often by
different teams within the service provider," he says.
Switching and transmission networks are beginning to blur, Kiel
says. "Data networks initially were built as an overlay on the
transmission network, but now trunking speeds in the switching network
are becoming equivalent to those in the transmission network. In
addition, switching systems are now providing protection
capabilities."
Ascend says it now can offer all the SONET/SDH transmission
functionality within the switching network. "To service providers,
simpler networks lower provisioning costs, and the reliability goes up
- there are just fewer boxes," adds Kiel. These claims will need to
be proven in the real world, and Ascend currently is working with
several service providers, including Williams Communications [WMB],
GTE Internetworking [GTE], and Frontier Corp. Through these customers
Ascend has begun interoperability and field testing between the GX 550
switch and three DWDM products: the Pirelli OMDS, Ciena [CIEN]
Multiwave Sentry, and NEC SpectralWave.
Williams is an interesting case in that it has had the luxury of
building a new network from scratch. The company left the wholesale
data market three years ago with the sale of its WillTel data unit to
LDDS, now part of Worldcom [WCOM]. Williams announced it was
reentering the market earlier this year, and signed on for $150
million of network equipment from Ascend. (See BNN, Jan. 20, 1998)
"We had three years to design our network, with no legacy
baggage and lots of cash," says Wayne Price, technology development
manager of networks at Williams. "We tried to figure out where
networking was headed by 1998. We looked into building an IP-specific
network, but saw there was still a huge demand for private lines, SNA,
and frame relay services. So, we went with ATM to optimize for data,
yet not turn our back on legacy traffic.
"With the technology changing rapidly, we wanted to avoid
putting in legacy equipment. DWDM had moved from lab to real networks
and we decided that the GX 550 was the only switch we could use in the
network, as it offered OC-48 trunking directly into fiber."
...Dumping SONET Saves a Lot of Bread
One of Ascend's selling points is that digital cross-connects
and SONET add/drop multiplexers are the most expensive parts of
today's network. The vendor claims that using its ATM switch to
replace this transmission equipment can lower a service provider's
provisioning costs by up to 75 percent.
Williams reports even better results in its preliminary
estimates: "We were shocked at the low cost of design," says Price.
He reports that eliminating legacy transmission equipment will save
Williams as much as 80 percent of the roll-out cost of a traditional
network.
Tom Nolle, president of the technology assessment company CIMI
Corp. agrees that SONET is becoming a bit of an anachronism in
networks that are increasingly becoming datacentric. "Basically SONET
doesn't earn you any revenue. It is plumbing," he says.
"SONET is the optical extension of the old TDM, T-carrier
system. SONET has all of the properties of T-1 and T-3 in terms of
rigidity of bandwidth and a circuit-oriented provisioning paradigm.
It is not efficient in a [variable bit-rate] environment. So, with
the exception of using it with as an optical interface specification
for point-to-point physical layer interface, [SONET] is not a useful
component in a 21st century network," he adds.
(Lucia Graziano, Ascend Communications, 978/952-1291; Wayne
Price, Williams Communications, 918/573-2254; Tom Nolle, CIMI Corp.,
609/753-0004)
LANGUAGE: ENGLISH
LOAD-DATE: June 9, 1998
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