article

Pump Up the Bandwidth

Posted: 08/1998

Pump Up the Bandwidth
Long-haul applications for dense wavelength division multiplexing (DWDM) are bigger,
faster and better than ever.

By Peter Meade

Bigger, faster, better. While this is the time of the year when football coaches look
for these qualities in their players, this quest is never out of season for long distance
carriers. Always seeking these qualities for their long-haul networks, carriers have found
dense wavelength division multiplexing (DWDM) technology delivers the best chance of John
Elway-like results.

But just as yesterday’s 250-pound linemen now are considered too lightweight for duty
on the gridiron, today’s carriers no longer can get by with the four- and eight-channel
DWDM offerings that emerged in the early 1990s when WDM first came on the scene.

Since that time, systems that have been pumped up to 16 channels have become as common
as bulked-up 300-pound linemen. Systems boasting 32 channels are becoming a reality from
an increasing number of vendors, with 40-channel models not far away. As these new
offerings boast more channels than ever, they help carriers squeeze more and more capacity
from their OC-48 backbones with equal skill for OC-192 on the way.

"No one talked about bandwidth like this several years ago," says Pawan
Jaggi, senior product planner, bandwidth transport planning for Fujitsu Network
Communications Inc. (Richardson, Texas). "Recent and future technological
advancements have ensured the economic attractiveness of using DWDM, because it comes down
to price in key enabling technology."

As today’s long haul offerings grow in capacity, at the same time, their pricing is
dropping to more attractive levels. Prices have come down 20 percent to 25 percent over
the past year, according to Mark Lutkowitz, president of Trans-Formation Inc., a
Birmingham, Ala.-based market research house.

Companies such as Alcatel Network Systems Inc., Cambrian Systems Corp., Ciena Corp.,
Ericsson Inc., Fujitsu Network Communications, Lucent Technologies Inc., NEC America Inc.,
Northern Telecom Inc. (Nortel), Osicom Technologies Inc., and Pirelli Cable and Systems
North America (Lexington, S.C.) are working hard to quench the desire that long distance
carriers have for bigger, faster, better systems. All these suppliers have shown DWDM
offerings that can be used to multiply the capacity of an existing single optical
fiber–which typically runs at 2.4 gigabits per second (gbps)–by 16 times or more and
support bandwidth at least 40gbps in each direction over a fiber pair.

This summer’s Networld+Interop and Supercomm trade shows looked like training grounds
for vendors that were demonstrating systems that are pushing closer toward tomorrow’s
40-channel systems that promise 100gbps, the equivalent of 10 OC-192 transmitters. For
example, at Supercomm, Fujitsu demonstrated its FlashWave 320G long-haul solution, which
can support up to 32 channels over OC-48 or OC-192 pipes to a maximum of 320gbps total
capacity. The system will operate with either single-mode or non-zero dispersion shifted
fiber, according to Jaggi. The 320gbps product, which currently is in field trials and
should be available in September or October, has a total capacity that represents the
equivalent of 4 million simultaneous phone calls, he says.

NEC America also boasts a 32-channel offering, called SpectraWave, which already is
undergoing a field trial with an undisclosed interexchange carrier, according to Steve
Cortez, manager of product marketing for the transport products management division of the
Herndon, Va.-based manufacturer. Designed for use with single-mode fiber in long-haul
applications, SpectraWave will handle up to 32 OC-48 channels for a maximum capacity of
80gbps.

Alcatel came to Supercomm with the latest–and biggest–version of its Optinex 1640
optical add/drop multiplexer (OADM). The 40-channel offering will be available later this
year, says Tim Krause, senior director, product line management, for optical networks.
Expect the product to go on a steroid program as future releases are expected to support
up to 240 channels via three upgrade paths, Krause says. With the added bulk comes
impressive flexibility; Optinex can handle any mixture of rates up to OC-192 on any
channel, he says.

The promising prowess of 240 channels is not that far-fetched when considering that
Lucent reportedly has already developed one laser that can replace 206 by using DWDM to
generate 206 separate wavelengths, each carrying 36.7 megabits per seconds (mbps) of data.

While so much has been made of the increased capacity of today’s long-haul DWDM
offerings, Roselyne Genin, the Dallas-based vice president, optical networking for
Ericsson, says capacity is not the top criteria on her customers’ scouting list. Instead
of bulk, they want brains; network uptime is their top priority.

"Customers want contingency fees for downtime," she says. "Users want
penalty clauses built into their service level agreements. It has gotten to where carriers
certainly can’t afford any network outages."

Dealing in the optical layer brings with it a new list of management challenges, says
Alcatel’s Krause. This layer will provide dynamic reconfiguration and restoration
capability while the synchronous optical network (SONET) and services layers take care of
the actual multiplexing and service interface functionality.

Ericsson’s Networker DWDM system from its Erion family, which has been available for
about a year, addresses these concerns by putting an increased emphasis on network
management, she says. Managing today’s growing optical networks is akin to the increased
congestion on our highways, Genin says. There are more cars than ever, more lanes than
ever with cars going faster than ever.

"We need to be able to maintain a balance between the cars and the lanes,"
she says. There is also the question of what to do if there is a breakdown, but a better
tack is to prevent as many mishaps as possible.

Not on the Same Wavelength

Aside from concerns about network management, carriers also must be concerned about how
they will connect their long-haul DWDM system to the growing number of short-haul or metro
systems that are coming on the market from companies such as Cambrian, Ciena, Osicom
Technologies Inc. (Santa Monica, Calif.) and Tellium Inc. (Oceanport, N.J.).

Even though Ericsson is one of the few vendors with a metro DWDM product that is
commercially available today, Genin says she does not expect any more than "islands
of metro applications" to take shape over the next six months. In the meantime, the
slow pace may be due to carriers not yet understanding how these emerging metro
applications will interface with their existing DWDM applications. The biggest hurdle:
today’s WDM solutions are vendor-dependent. When it comes to the subject of DWDM system
interoperability, most vendors are not on the same wavelength.

This means carriers with long-haul DWDM systems have been locked into one vendor–at
least until several months ago, when Cambrian and Lucent demonstrated interoperability
between their respective products at Supercomm. At Cambrian’s booth, the company
demonstrated how its OPTera Metro DWDM system works with Lucent’s WaveStar Optical Line
System (OLS) 40G metro application. While at its booth, Lucent showed its OLS 400G
long-haul system works with OPTera Metro.

Perhaps surprisingly, the interoperability process took only months, says Solomon Wong,
assistant vice president of marketing for Cambrian. "It was not that hard–just a
matter of initiative and the chemistry [between the personnel at the two companies] was
instantly right," he says.

The demonstrations proved that real-world applications, such as the two companies’
metro systems working together or Lucent’s long-haul system operating with either of the
two metro applications on either ends, are possible, says Kathy Szelag, vice president of
marketing for Lucent’s optical networking group. Given the interest this stirred at both
booths, Cambrian’s Wong says he would consider orchestrating other pairings.

GST Telecommunications Inc., a Vancouver, Wash.-based provider of both local and long
distance service, is seriously interested in this matter because eventually there will
come a time when short- and long-haul DWDM systems must work together seamlessly in the
network, says Mitch Mollard, GST director of transmission engineering.

The two eventually will merge, says NEC’s Cortez. It will not happen anytime soon,
however, so until that time, trade show demonstrations will have to suffice.

"Demos are one thing, but how you do it in the network is another," admits
Cambrian’s Wong. His sentiments are echoed by Lucent’s Szelag, who was quick to say the
interoperability demonstration was "simple." It lacks some of the alarms and
performance monitoring that would be necessary for real-world deployment, she adds.

"But it’s a start, a good start," she says. "We got to use a lot of what
we learned through our work with SIF (SONET Interoperability Forum). It certainly was
easier than SONET interoperability."

"For DWDM systems to reach their potential, they must operate and interoperate
into the network cloud and out to the customer premises," says Wong.
Carrier-to-carrier interfaces, involving cooperation between local exchange carriers
(LECs) and competitive LECs (CLECs) as well as IXCs, are still to be defined. This is not
a race where a relative newcomer like Cambrian, a spin-off of Newbridge Networks Inc.,
would want to take the lead, Wong says.

"Defining it wrong could hurt our business and no one wants to be at a
disadvantage," he adds. "It’s best done through consensus."

Cambrian (Kanata, Ont.) is scheduled to deliver the first of its products by the end of
the year, Wong says. This time frame is shared by many of the metro competitors. The
fourth quarter should bring Fujitsu’s 16-channel FlashWave Metro offering, according to
Jaggi. Based on the FlashWave 320G system, Metro will deliver 16 channels at OC-48 for a
maximum capacity of 40gbps for distances of 60 kilometers (km) to 80km, he says.

The timing and ability to deliver on these promises will play a key role in who emerges
from the pack to be a leader in the DWDM metro race, says Michael Arrelano, an analyst
with Degas Communications Inc., a New York-based consultancy.

Stepping Forward

While the emergence of DWDM metropolitan applications is encouraging, the technology
really needs more Bell companies to step forward with deployment and interoperability
plans. So far, only Bell Atlantic Corp. has officially announced a DWDM commitment in its
network upgrade, while all the other Bell siblings are still in the testing phase. In
addition, look for CLECs to step forward.

"CLECs can move so much faster than traditional telcos," says
Trans-Formation’s Lutkowitz. "They can view something at Supercomm, go through some
testing and have it in place in their networks in a matter of months."

The ability to deliver new products in a matter of months is of particular importance
to Ciena and Lucent, both of which must deliver new DWDM metro products to Bell Atlantic
according to the parameters drawn up in their recent agreement. While the original pact
was drawn up to give the two suppliers an equal split of the DWDM spoils in the massive
network upgrade, this will pan out only if both maintain certain delivery dates. Both
vendors’ metro systems currently are being scrutinized under laboratory conditions, with
Ciena being given a slight lead in the process, according to reports.

These are especially busy times at Ciena, because the company also is occupied with the
early stages of its $7.1 billion merger with Tellabs Inc. (Lisle, Ill.).

"This merger is all about managing bandwidth," says Trans-Formation’s
Lutkowitz. "With Tellabs’ experience in the regional holding company market, the
companies can now tackle the biggest markets."

Several rival suppliers mentioned that if Ciena had an Achilles’ heel, it was network
management, and this shortcoming should be alleviated by Tellabs’ skill in this area, he
says.

"The real challenge in WDM going forward is network management," says Brian
McFadden, general manager of optical network applications at Nortel. "In the future,
you’ll need to be able understand the quality of the signal all along the route. Today
[most systems] just say [whether] the WDM link is working or not working."

By combining forces, the Ciena-Tellabs team should be able to challenge Lucent for DWDM
market leadership, according to Lutkowitz, who adds that Alcatel, Nortel and Pirelli are
in the next pack. Alcatel’s Krause says he takes the glass-half-full approach to the Ciena
news. The merger buys his company and others an opportunity to increase their pace while
the new pairing is preoccupied trying to successfully combine forces, he says.

Terabit Terrors

No matter which vendor emerges to lead the pack, the trend of "bigger, faster,
better" will proceed into the next century. Soon even systems such as Fujitsu’s
320gbps will have sand kicked in its face. Lucent’s WaveStar OLS 400G offering, for
example, can handle up to eight fibers each transmitting 400gbps, for a total of 3.2
terabits per second. Welcome to the next plateau called ultra-DWDM, coming sometime this
fall. And bigger IS better; using UDWDM gear could save carriers up to 40 percent in
equipment savings over systems with less capacity, says Lucent’s Szelag.

According to Fujitsu’s Jaggi, when networks reach stratospheric proportions they must
consider two factors: either expanding the bandwidth of their optical amplifiers or
reducing the spacing between channels. Accomplishing this will permit carriers to move
deeper into terabit transmission rates. Look for this to happen about the same time the
National Football League debuts its first 400-pound lineman, a reality that isn’t far off.


Leave a comment

Your email address will not be published. Required fields are marked *

The ID is: 67873