Excerpt from 1998 startup Sycamore Networks Inc. [Desh Deshpande, founder and chairman]
From sycamorenet.com
Intelligent optical networking
If we look at how the public network is currently architected, the problems
becomes readily apparent. Today, the transmission network is comprised of three
elements: Fiber that provides the raw capacity; DWDM multiplexers that increase
raw capacity on a specific fiber route by dividing a fiber strand into multiple
lightpaths, essentially creating more fiber; and SONET transmission equipment
that provides the network intelligence and converts the capacity into
usable/salable bandwidth.
In today's environment, traffic from voice and data networks is multiplexed by a
SONET/SDH ADM (add/drop multiplexer) or SONET/SDH Terminal and
converted from an electrical signal to an optical signal for transport over fiber.
Since the fiber itself is just a physical medium and has no intelligence, the
process to move the traffic is laborious:
At each network transit point the traffic is fed back into a SONET
Network Element
Converted to an electrical signal,
Examined to see which traffic should be terminated at this juncture,
Terminated traffic is extracted,
New traffic is added,
The entire stream is converted back to an optical signal for transport to
the next network element
SONET is a hierarchical electrical transmission standard which was designed to
scale voice networks. In addition to grooming and converting traffic to and from
optical format, SONET provides the intelligence for fault and performance
management and protection against fiber cuts across the network. The burden of
converting all traffic from electrical to optical at each network juncture adds
enormously to the cost and complexity of the network. Scaling a SONET network
is also a challenge since SONET equipment is speed sensitive -- a forklift upgrade
is required to migrate a SONET network from one speed to another (e.g. OC-48 to
OC-192).
Clearly, a solution is required that delivers the intelligence of the SONET
infrastructure without the cost, complexity and limitations of electrical to optical
conversions.
Intelligent optical networking offers that solution. Intelligent optical networking
moves the network intelligence from the electrical domain into the optical domain
and delivers the functionality of SONET with the capacity of DWDM.
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The intelligent optical network
By bringing intelligence into the optical domain, there is the opportunity to create
a flexible, high capacity intelligent optical network that will deliver an abundance
of usable bandwidth. In an intelligent optical network, electrical/optical
conversions are eliminated and the traffic remains in the optical domain as it
transits the network.
In creating an intelligent optical network, intelligent optical networking
technologies will enable service providers to leverage their existing infrastructure
while developing the foundation for new services. Over time, SONET, which used
to describe an entire layer of a network and a set of distinct products from legacy
vendors will become a service interface on next generation optical networking
products.
In the intelligent optical network, the lightpath becomes the transport medium
versus the physical fiber strand. Services are mapped directly onto lightpaths
without any intervening transmission equipment. With the removal of a layer of
transmission equipment, the network is greatly simplified and service providers
can quickly add new services or increase bandwidth without impacting existing
traffic.
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The value of an intelligent optical network
Intelligent optical networking offers significant performance and cost benefits to
service providers which are derived through the simplification of the network
infrastructure. In addition to the technical benefits, Intelligent optical networking
will provide a foundation for success in today's divergent world and will facilitate
convergence as the market begins to consolidate.
Incumbent service providers like the RBOCs are faced with the challenge of
creating a new data service revenue stream without impacting the revenue they
currently receive from their voice services. By creating an intelligent optical
network, a separate leading-edge data network can be easily constructed in
parallel with the voice network utilizing the same physical fiber assets.
Additionally, RBOCs faced with regulatory wholesale obligations can lease
lightpaths instead of fiber and thus protect precious physical resources.
For service providers who make their money from selling capacity to other
service providers, an intelligent optical network offers the option of selling
lightpaths rather than physical fiber. With the addition of new cards into existing
systems, more lightpaths can be sold utilizing the same physical fiber and
bringing revenue growth without major capital investment.
For new entrants, an optical network foundation provides the means to establish
an area of service specialization and migrate the business to a full service offering
as convergence and consolidation begins to take hold.
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The evolution of the intelligent optical network
Creating a new network foundation will be an evolutionary process that will most
likely start in the access and interoffice segment of the public network. It is here
that the technology is available and where the need is the greatest. Advances in
technology now make it possible to transmit in optical format for thousands of
km without re-entering the electrical domain. Today, the access and interoffice
segment of the network has become a bottleneck, stalled at megabyte speeds
while the backbone network is being scaled to terabyte speeds and corporate
LANs are operating at gigabyte speeds.
Though access and local distribution is frequently envisioned as a single
point-to-point connection delivered by the local service provider from the
customer premise to the long haul provider, the reality is much different.
This segment of the network is actually a complex network of SONET rings and
linear connections operating at a variety of speeds. Customer traffic originates
and terminates at all points in this network environment. The magnitude of the
problem is phenomenal --- Since 1992 more than 200,000 SONET devices have
been installed in the USA, alone has more than 8000 SONET rings in its network
area.
Today we are at the beginning of optical network evolution -- in the next few
years intelligent optical networking will make its way from the access segment of
the network through all segments of the network.
Starting with the harnessing of capacity and expanding to a vision of a world of
networked virtual lightpaths (lambdas) where service providers will have the
ability to give their customers a lightpath through the network, intelligent optical
networking will transform the public network environment and will yield a
network foundation which will enable the delivery of WAN services at LAN
speeds.
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Sycamore and the intelligent optical network
Sycamore Networks is a pioneer in the new field of intelligent optical networking.
Our mission is to increase the performance and reshape the economics of the
public network through the creation of an intelligent optical infrastructure. In
short -- the goal is to create a network foundation that can deliver an abundance
of cost-effective bandwidth to deploy new services and new high speed
applications.
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The intelligent optical networking market
The intelligent optical networking market is a new market that will bring its own
class of products, the first generation of which will appear in 1999. Analysts have
quantified the SONET and DWDM markets and are just now beginning to look at
the optical networking market. Though market sizing cannot currently be
predicted with accuracy, it is clear that in the short term optical networking will
co-exist peacefully with SONET and DWDM. Over time intelligent optical
networking will erode market growth in both these areas and will become the
predominant means of building networks.
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