Transparent optical networks are a necessity if network operators are to keep pace with the seemingly insatiable demand for bandwidth at a reasonable cost. The "bandwidth spiral" will move at an increasingly rapid pace as new applications are developed to take advantage of advancements in optical technology that reduce the cost and complexity associated with offering new services. Luxcore will help service providers profit from the bandwidth spiral by providing systems that incorporate new, innovative technology to help realize the lowest cost per gigabit. Luxcore's enabling technologies provide an innovative solution to the development of a tunable flexible, scalable pure optical network.
There are several technical issues that must be addressed to realize pure optical networking and photonic wavelength-routing; specifically, flexible transport technology, photonic switching, advanced network intelligence, and automated end-to-end bandwidth provisioning.
Transport technology is key in the development of pure optical networks must be flexible and scalable as well as bit rate independent and protocol transparent. More importantly, pure optical networks should incorporate photonic switching as a fundamental building block.
Photonic switching can be defined as the ability to quickly direct (switch and transport) bursts of modulated light (wavelengths/ultrafast circuit-switching), maintained solely in the optical domain, to any or all outgoing optical ports.
Photonic switching is defined by three variables:
1) a unit of optical bandwidth (wavelength today, optical packet
in the future);
2) processing speed (milliseconds today, nanoseconds in the near future)and;
3) an optical network computing function (modulation, transmission, signaling, optical multicast, wavelength conversion, add-drop, regeneration, and cross-connect switching).
Photonic switching can be static or dynamic depending on bandwidth demand.
Luxcore's Enabling Technologies
Optical Switch Core
The use of a fully transparent optical switch core in the transport architecture
is essential in improving the efficiency and scalability of optical networks.
A pure optical switch core eliminates the need for optical-electrical-optical
(OEO) conversions to manipulate wavelengths. Maintaining signals in the
pure optical domain eliminates hundreds of components (such as transponders,
fiber connections, patch panels) that contribute to the "bandwidth
bottleneck".
A pure optical switch is also far more flexible and scalable than its electrical or hybrid counterparts because a pure optical switch manages photons and not bit rates. Carriers do not need to replace expensive opto-electric transponders when higher transmission rates become available.
Flexible Wavelength Selection
As the demand for bandwidth increases, a need for additional
wavelengths to be dropped or added at a particular node in the network. It would be advantageous to network operators if the transport
technology deployed was capable of dynamically allocating additional bandwidth
(wavelengths), via software and control algorithms, to various nodes in
the network without requiring major, expensive, and time-consuming modifications.
The use of tunable laser and wavelength-selective device technology allows flexible configuration and operation of the pure optical network without requiring expensive modifications. Again, the use of this technology allows efficient and cost-effective bandwidth utilization providing additional revenue opportunities to the network operator. Several innovative schemes have been utilized by Luxcore to flexibly and dynamically terminate and add traffic at a given node. Another benefit of Luxcore's technology implementation is that interchannel crosstalk-like noise generated by interactions of closely spaced channels in multiplexed multi-wavelength traffic is greatly reduced.
Pure Optical Wavelength Conversion
High capacity optical networks should include some means of performing
wavelength conversion to resolve wavelength contention. As the number
of DWDM nodes increases, the probability of blocking at a node increases
when two channels at the same wavelength are routed to the same output
port. Therefore, wavelength conversion is a necessity for effective, efficient
use of bandwidth in very large, high capacity networks with dynamic bandwidth
demands.
Wavelength converters can be classified as opto-electronic or pure optical
devices. It is beneficial in the pure optical network to incorporate
pure optical wavelength conversion devices. Transparency is extremely
important to ensure easy, inexpensive upgrades in network capacity in
the future.
Broadband Optical Amplification
Optical networks requiring long haul and ultra-long haul capabilities
have to utilize transparent amplification schemes to extend the reach.
EDFAs have become the standard in providing amplification for long-haul
DWDM systems. Conventional EDFAs are fairly broadband, ~35nm centered
around 1550nm (C band); however, to extend the capacity of DWDM systems,
amplification schemes are needed with even wider bandwidth to take advantage
of the low-loss region in silica fibers.
Amplifiers that are capable of operating in the S and L bands are necessary for seamless evolution to higher capacity. Novel hybrid fiber amplifier designs incorporating rare earth doped fiber amplifiers and Raman amplifiers can provide the necessary broadband amplification scheme.
Dispersion Management
Long-haul high bit rate transmission systems also have to incorporate
dispersion management to ensure the integrity of the information. Chromatic
dispersion and polarization mode dispersion (PMD) can drastically affect
the system performance of high-speed transmission systems operating at
10 Gb/s and above due to pulse spreading.
Dispersion management schemes have to compensate for chromatic dispersion introduced by the propagation of the signal over significant lengths of fiber, as well as, the impairments introduced by the differential group delay caused by different group velocities of the two polarization eigenmodes. The degeneracy of the fundamental mode of the light traveling in the fiber is removed by randomly varying birefringence caused by imperfections, inhomogeneities, geometrical and environmental perturbations. This causes the polarization eigenmodes to travel at different speeds, which leads to pulse spreading and noise, thus limiting the bit rate-distance of the overall system.
The effect of PMD is especially dominant in systems utilizing older fiber
designs. Broadband, dynamic dispersion compensation schemes are necessary
to maximize the bit rate-distance performance of these systems and ensure
signal integrity.
Advanced Network Intelligence and Bandwidth Provisioning
Luxcore is developing advanced real-time end-to-end wavelength provisioning, traffic engineering and fault isolation software that realizes maximum functionality of its pure optical internetworking product solutions. The distinguishing factor of Luxcore's software architecture is the exploitation of Java based technologies to permit rapid deployment of internationalized QoS and CoS-based network services.
Luxcore's approach is to field a modular and extensible software architecture that combines the best features of classic element management with policy based traffic engineering. Luxcore software supports multiple, configurable route calculation algorithms as well as configurable policy based route protection and restoration regimes. Luxcore element management, traffic engineering, and network element software is designed from the onset to be fault tolerant and robust. It will support advanced real-time node and link monitoring, network topology and link attribute auto discovery, bandwidth demand forecasting, and capacity planning. Our software API will support a number of standard interfaces including CORBA, SNMP, TL1, XML, and LDAP.
Luxcore software is developed in a rigorous, quality centric environment by highly experienced systems and software engineers. The Luxcore software development approach is based on detailed practices defined in Carnegie Mellon University's Software Engineering Institute (CMU/SEI) Capability Maturity Model Integrated (CMMI) for Systems and Software Engineering.
Luxcore develops software using a managed process designed to map specific CMU/SEI CMMI systems and software development practices to comply with ISO 9001: 2000 edition quality goals. Luxcore is committed to developing the highest quality, most intuitive, and best performing software in the emerging OTN management and traffic engineering software market.
Luxcore makes every reasonable attempt to conform to emerging IETF, ITU, and industry standards. The innovation in the software space is as advanced and forward thinking as the technological innovations contained in the optical hardware. Luxcore is committed to being a leader in the development of advanced management and control software for the emerging pure optical transport market.
The Luxcore product portfolio incorporates innovative approaches, technologies, optical hardware and software, that will aid in the deployment of true photonic switching in optical network.
Marcus W. Shute, P.E., Ph.D., Vice President, Advanced Technologies
