Design and Analysis of Optical Packet Switch Routers

Int'l J. of Communications, Network and System Sciences, 2011

Optical Packet Switching (OPS) and transmission networks based on Wavelength Division Multiplexing (WDM) have been increasingly deployed in the Internet infrastructure over the last decade in order to meet the huge increasing demand for bandwidth. Several different technologies have been developed for optical packet switching such as space switches, broadcast-and-select, input buffered switches and output buffered switches. These architectures vary based on several parameters such as the way of optical buffering, the placement of optical buffers, the way of solving the external blocking inherited from switching technologies in general and the components used to implement the WDM. This study surveys most of the exiting optical packet switching architectures. A simulation-based comparison of input buffered and output buffered architectures is presented. The performance analysis of the selected two architectures is derived using simulation program and compared at different scenarios. We found that the output buffered architectures give better performance than input buffered architectures. The simulation results show that the-broadcast-and-select architecture is attractive in terms that it has lees number of components compared to other switches.

Journal of Computer Science, 2011

Problem statement: Optical Packet Switching (OPS) and transmission networks based on Wavelength Division Multiplexing (WDM) have been increasingly deployed in the Internet infrastructure over the last decade in order to meet the huge increasing demand for bandwidth. Several different technologies have been developed for optical packet switching such as space switches, broadcast-and-select, input buffered switches and output buffered switches. These architectures vary based on several parameters such as the way of optical buffering, the placement of optical buffers, the way of solving the external blocking inherited from switching technologies in general and the components used to implement WDM. Approach: This study surveys most of the exiting optical packet switching architectures. A simulation-based comparison of input buffered and output buffered architectures were presented. Results: The performance analysis of the selected two architectures derived using simulation program and compared at different scenarios. We found that the output buffered architectures give better performance than input buffered architectures. Conclusion: The simulation results shows that the-broadcast-and-select architecture is attractive in terms that it has lees number of components compared to other switches.

Journal of Lightwave Technology, 2005

Dense Wavelength-division multiplexing (DWDM) technology offers tremendous transmission capacity in optical fiber communications. However, switching and routing capacity lags behind the transmission capacity, since most of today's packet switches and routers are implemented using slower electronic components. Optical packet switches are one of the potential candidates to improve switching capacity to be comparable with optical transmission capacity. In this paper, we present an optically transparent ATM (OPATM) switch that consists of a photonic front-end processor and a WDM switching fabric. A WDM loop memory is deployed as a multi-ported shared-memory in the switching fabric. The photonic front-end processor performs the cell delineation, VPI/VCI overwriting, and cell synchronization functions in the optical domain under the control of electronic signals. The WDM switching fabric stores and forwards aligned cells from each input port to the appropriate output ports under the control of an electronic route controller. We have demonstrated with experiments the functions and capabilities of the front-end processor and the switching fabric at the header-processing rate of 2.5Gb/s. Other than ATM, the switching architecture can be easily modified to apply to other types of fixed-length payload formats with different bit rates. Using this kind of photonic switches to route information, an optical network has the advantages of bit rate, wavelength, and signal-format transparencies. Within the transparency distance, the network is capable of handling a widely heterogeneous mix of traffic, including even analog signals.

2009

In this paper, a novel optical packet switch (OPS) architecture is proposed and its scheduling algorithm is implemented and analyzed. The proposed architecture makes use of shared wavelength exchange optical crossbars (WOCs) to reduce wavelength conversion complexity. Simulation results show that, under heavy traffic loads, the conversion cost of the proposed OPS architecture is only 25% of that of a typical OPS architecture. Moreover, under low traffic loads, the conversion cost of the proposed architecture can be reduced to half of that of typical OPS designs.

-Optical packet switching enables the transfer of packet signals in the optical domain on a packet-by-packet basis. In conventional electronic routers, all input optical packets are converted into electrical signals that are subsequently stored in a memory. Optical packet switching is promising to offer large capacity and data transparency. However, after many years of research, this technology has not yet been applied in actual products, because of the lack of deep and fast optical memories and the poor level of integration. It will be overcome not only through technical breakthroughs but also through clever network design, making optimal use of optics and electronics. Developments in OPS seem to lead integration of optical and electronic networks and the use of optical burst switching (OBS). High-speed digital fiber-optic transmission using subcarrier multiplexing(SCM) is investigated both analytically and numerically. In order to reduce the impact of fiber chromatic dispersion and increase bandwidth efficiency, optical single-sideband (OSSB) modulation was used. Because frequency spacing between adjacent subcarriers can be much narrower than in a conventional. Dense Wavelength Division Multiplexing (DWDM) is an optical multiplexing technology used to increase bandwidth over existing fiber networks system, nonlinear crosstalk must be considered. Although chromatic dispersion is not a limiting factor in SCM systems because the data rate at each subcarrier is low, polarization mode dispersion (PMD) has a big impact on the system performance if radiofrequency (RF) phase detection is used in the receiver. In order to optimize the system performance, tradeoffs must be made between data rate per subcarrier, levels of modulation, channel spacing between subcarriers, optical power, and modulation indexes. A 10-Gb/s SCM test bed has been set up in which 4×2.5 Gb/s data streams are combined into one wavelength that occupies a 20-GHz optical bandwidth. OSSB modulation is used in the experiment. The measured results agree well with the analytical prediction. In the optical domain, the Optical Packet Switching(OPS) paradigm is similar to electronic packet switching, except that the payload of the packets are switched and buffered in the optical domain while the headers, which contain control information, are processed electronically. In this paper, we focus on slotted OPS networks, where optical packets are of a fixed duration, and are aligned at the inputs of the switching node. Slotted OPS with a packet size in the order of 1μs has been concluded as a promising alternative for future OPS backbone networks. The switching architecture (switch fabric) is the node component responsible of the transfer of the optical packets from the input ports to the output ports of the switching node. This requires a packet-by-packet switching operation.