"Optical Networking Gets Smarter
If 2000 was the year that intelligent dense wavelength division
multiplexing (DWDM) transport started to reach critical mass, 2001
is expected to witness the first serious deployments of intelligent
optical switching at the network edge as well as in the core.
“The next natural step is going to be switching wavelengths or
switching sub-rate services inside those waves,” predicts Rick Barry,
co-founder and chief technology officer of Chelmsford,
Massachusetts-headquartered optical networking concern Sycamore
Networks.
There are a number of drivers at work here.
As data volumes in the network swell, one of these drivers,
according to Sycamore co-founder and chairman Gururaj Desh
Deshpande, is the requirement to recreate the same levels of
bandwidth in the metropolitan area network (MAN) and wide area
network (WAN) that have already been achieved in the local area
network (LAN).
Increasingly the requirement is for gigabit Ethernet capacity. “The
market is in the midst of the Ethernet renaissance,” states Bill
Hawe, chief technology officer of Nortel Networks.
“Ethernet has become the compelling interface across many types
of networking equipment and service provider access solutions. We
are continually driving its cost down and its performance up.”
In the past, the issues with Ethernet were its scalability, reliability
and limited reach. The integration with optical elements, however,
can give Ethernet scalability to 10 Gb/s (gigabits per second),
carrier-grade reliability and greater reach.
Both Nortel and Sycamore are equipment suppliers to Utfors, a
Scandinavian operator offering Gigabit Ethernet services on its new
6,500 km (kilometers) intelligent broadband fiber network. This
network connects the 50 largest towns and cities of southern and
central Sweden with Oslo, Copenhagen and Helsinki.
“Ethernet provides a better cost structure than competing
technologies, provides more bandwidth as it scales to higher
speeds and offers the best opportunity for an end-to-end, seamless
protocol that is unmatched by competing technologies,” says Fazal
Abbas, director of applications for Lara Networks in San Jose,
California.
The industry’s move to IP, Abbas contents, bodes well for Ethernet
because the technology has long been coupled to IP.
“The pressure for performance and convergence of service will
further push the market demand to a single protocol. There are two
ways for this trend to manifest: existing Sonet/ATM backbone
technologies move to the enterprise, or Ethernet moves to the
backbone and MAN networks. The most likely trend shows Ethernet
moving from the enterprise to the Man and backbone,” Abbas says.
David Yates, vice president of marketing for Atrica Inc. in San Jose,
California, describes 10/100 Ethernet connections in the MAN as the
likely hot technology for access in 2001.
“The standards are almost there and the solutions will be there in
the next 12 months,” Yates says. “The demand is there from
Internet-based applications, the infrastructure is getting there as
companies install fiber and new service providers are springing up
to provide services that are amazingly affordable.”
For service providers, Nortel Networks says an optical Ethernet
solution enables multiple wholesale access and enterprise
outsourcing services. In addition, the technology can support
bandwidth intensive applications for residential customers such as
movies-on-demand, networked video gaming and more.
Nor is this search for higher and higher capacity confined to highly
specialized operators or the bandwidth-fixated early adopter North
American market.
The opening up of local access through xDSL (digital subscriber line),
wireless local loop and 3G cellular technologies also drives user
demand for broadband capacity throughout Europe.
“Operators need to adapt their networks to very high traffic growth,
whenever and wherever it appears,” comments Fred Gastaldo, chief
operating officer of Paris-headquartered broadband service provider
LDCOM.
LDCOM now is constructing an intelligent, switched 14,000 km fiber
network and metropolitan infrastructure in and between 20 major
European cities, with extensive coverage in France. It plans to offer
a suite of optical services including wavelength services, managed
bandwidth and optical virtual private networks (VPNs).
A second driver of intelligent optical networking is the on-going
need to displace cost in the network, an objective that can be
progressed by minimizing the frequency of optical-electrical-optical
conversion.
A third driver is for service providers to be more customer-friendly
and market-responsive in a ferociously competitive commercial
environment. Deshpande reckons it sometimes now takes several
months to provision new end-to-end network services and that it
will be necessary to cut this process to minutes and, ultimately, to a
point-and-click real-time exercise.
But while there is consensus that optical networking will need to
become much more intelligent, flexible and scalable, there are
differing views on what these networks will look like in detail.
Sycamore, for example, anticipates a fully switched meshed
architecture, with optical switching in the core and opto-electronic
machines at the edge. The company also foresees the survival of
synchronous digital hierarchy/synchronous optical network
(SDH/Sonet) in new generation forms, but believes ring networks
are an endangered species due to their lack of flexibility and ready
scalability, and the inefficiency of many of their one-to-one
protection mechanisms.
While agreeing that much protection designed into rings is wasteful,
Columbia, Maryland-headquartered Corvis Corp. forecasts that the
SDH/Sonet framing layer eventually will disappear and you’ll be left
with a beefed-up Internet protocol (IP) on DWDM.
While such a wholesale transformation is not likely to happen in
2001, the foundation for this type of migration is already under way.
“We will certainly get to IP over glass,” states Shyam Jha, Corvis
vice president of marketing.
Corvis also seems to set greater store than Sycamore on all-optical
switching, arguing that transmitting and switching traffic entirely in
the optical form as wavelengths of light results in higher
performance and reliability for carriers, while significantly reducing
the capital and operational costs associated with today’s hybrid
electrical optical switching.
Last year, Corvis announced the deployment by Broadway
Communications of the first commercial all-optical switch to be used
in a nationwide network. The Corvis machine has a 2.4 Tb/s
(terabits per second) capacity, and the company maintains it is a
key element in enabling point-and-click provisioning of wave
services.
“Corvis’ delivery of the industry's first all-optical switch to Broadwing
is a defining moment in our industry,” opines Rick Ellenberger,
president and CEO of Broadwing Inc.
“The integration of the Corvis all-optical switch into the world's first
all-optical network, now being deployed by Broadwing, will enable
us to deliver the killer platform that makes possible new
applications and services for our customers.”
How you manage intelligent optical networks also is the subject of
some industry debate.
Many experts see multiprotocol label switching (MPLS) as a key part
of the optical management solution, although Dr. Chris Lilly,
managing director optical routing vendor ilotron based in Mayfield,
England, warns operators not to put all their network eggs into the
one MPLS basket when deploying next-generation technology.
He advises operators to “sweat” their existing management assets
such as TMN.
MPLS, ilotron believes, will not be standardized in time for field
implementation of the optical superhighways that will be created by
optical cross connects. To allow the migration from TMN to optical
cross connects, ilotron itself provides a Q interface which is
compliant with simple network management protocol (SNMP)-based
applications.
In addition, ilotron provides network elements with a distributive
management capability, effectively creating what the company
describes as an “MPLS lite.” This is designed for integration with the
legacy TMN structures to enable fast protection and provisioning at
the optical transport layer, while maintaining the useful features of
TMN.
-- John Williamson "
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