Vendors Advance on Network Remedies


The push toward all-optical, wavelength-specific networking
solutions for data services has picked up steam in recent weeks.

Most recently, several vendors agreed on a new approach to
integrating the management of multiple protocols in next-generation networks.

The Network Management Forum said it had reached agreement
on an interface that will greatly simplify the management of network elements associated
with different types of protocols and different vendor systems. The forum consists of
Lucent Technologies, Nortel, Tellabs Inc. and Fujitsu Network Systems Inc.

The initial iteration of the interface solution -- based on
the object-management-oriented protocol known as "CORBA" (Common Object Request
Broker Architecture) -- is targeted toward managing existing long-haul networks, but forum
participants said the solution has important implications for the use of dense wavelength
division multiplexing in all-optical regional and long-distance networks, as well.

"By moving to a CORBA-based interface, we're
creating an environment that allows us to accommodate virtual facilities management on a
per-wavelength basis," said Tim Fritzley, vice president of network solutions at

The ability to manage "virtual facilities" where
IP (Internet-protocol) packets might be carried over one wavelength, SONET (synchronous
optical network) frames over another and ATM (asynchronous transfer mode) over a third is
central to the evolving strategy at Tellabs, as it seeks to complete its acquisition of
DWDM supplier Ciena Corp., Fritzley said.

Today, while individual vendors supply complete
network-management systems based on the Telecommunications Management Network framework,
these systems are not interoperable with each other, meaning that network managers
overseeing elements supplied by multiple vendors must work with multiple management
systems, greatly complicating their tasks.

By agreeing on a common interface between the performance
information generated by myriad network elements, such as cross-connects and multiplexers,
and the management layer, the NMF members hope to promote more flexible applications of
optical technology, including DWDM.

"Once the industry has stabilized on a regional
[all-optical DWDM] architecture, we'll be in a better position to focus our attention
on whatever refinements are necessary to accommodate management integration for such
applications," said Michel SansChagrin, director of the Integrated Network Manager
system at Nortel. "But what we've already done here can be directly applied in
the long-haul DWDM domain."

The NMF agreement comes as network operators begin to take
advantage of DWDM to more tightly couple data networks with the optical layer by
eliminating the need for SONET multiplexers between routers and fiber links.

For example, Sprint Corp. plans to convert its
Internet-backbone segments to OC-48 (2.5 gigabits per second), using DWDM technology from
Ciena and the new gigabit-switch routers from Cisco Systems Inc., starting this fall, said
Ian Reingold, director of data engineering at Sprint.

"You can fast-forward and see how we will continue to
integrate and put the technology into the routing platform," Reingold said.
"Convergence into the photonic layer is the vision of where the technology wants to

As currently configured, these new IP-over-SONET systems
perform the SONET framing at the router before converting the signal to light, and they
then transmit the wideband light beam a short distance to a transponder. The transponder
converts the wideband light to an electronic signal for insertion into a narrowband,
lightwave-specific WDM laser.

The next goal in the system design is to eliminate the need
for a transponder by being able to feed a narrowly defined lightwave from the router into
the fiber.

Similar efforts with regard to direct input of ATM and
Ethernet, as well as IP signals, into specific wavelengths are under way throughout the
data-networking community, said Bill Gartner, vice president for
optical-networking-product development at Lucent.

If agreement can be reached on a common approach to route
protection at the optical layer whether the signal format is ATM, Ethernet, or IP, then
the network can deliver all of the packages through the same mesh infrastructure, saving a
tremendous amount of capacity that would otherwise be eaten up by typical
SONET-restoration procedures, Gartner added.

"It's a question of how much you have to
compensate for as you move to fewer layers," Gartner said. "For example, if
I'm operating from the IP side, and I want the same quality in my IP service as I can
get in ATM, then I migrate quality of service to the IP layers. And if I believe that the
SONET-recovery layer is something that the network provider should have to be concerned
with, then you can assume that the restoration migrates to the optical layer."

Such issues are currently being addressed through another
new industry group, known as the Optical Internetworking Forum. NMF representatives said
they will be working with the OIF to achieve the management integration that is essential
to making fully meshed DWDM a reality at the regional-networking level.