Parallel transfer optical packet switches

For efficient utilization of bandwidth in optical packet switching, the guard time Tg between packets should only be a small fraction of the packet transmission time Td. Since the guard time Tg of existing packet switching approaches must be larger than the reconfiguration time Tsw of optical switches, this imposes a stringent demand on the switch reconfiguration time Tsw as the transmission rate of optical fibers increases. By using batch transfer of packets or multiple switching fabrics in parallel, the requirement on the switch reconfiguration time can be significantly relaxed. The utilization of the transmission links can be greatly improved because the guard time between packets is no longer constrained by the switch reconfiguration time. © 2009 IEEE.published_or_final_versio

Performance Model of Multichannel Deflection-Routed All-Optical Networks With Packet Injection Control

Deflection routing is a feasible approach to resolve the output contention problem in packet-switched networks when buffering of packets is not practical. In this paper, we investigate the performance of multichannel deflection-routed networks with no packet injection control, strict packet injection control, and a simple token-bucket-based packet injection control. The analytical performance models of multichannel deflection-routed networks with strict packet injection control are derived. Simulation results show that the analytical models can accurately predict the performance regardless of the network topology, number of channels, and packet injection control methods. We observed that the end-to-end throughput-delay and the packet re-transmission performance at sources can be largely improved by using simple packet injection control mechanisms such as the proposed token-bucket-based method.postprin

Improving the performance of optical burst switching with large control overhead

In optical burst switching (OBS) system, the throughput decreases rapidly with increase in control packet processing time Tcp. The negative impact of Tcp will become significant as the optical fiber transmission rate increases. By analyzing the relationship between the throughput and Tcp, we attempt to improve the throughput. Different possible solutions are discussed. We found that using extra random offset time can significantly improve the throughput at the expense of increase in data burst delay. ©2008 IEEE.published_or_final_versio

The decomposition of a blocking model for connection-oriented networks

Two general-purpose decomposition methods to calculate the blocking probabilities of connection-oriented networks are presented. The methods are based on either the call status or the link status of the networks, and can significantly reduce the required computational times. A heuristic is presented to simplify the application of the proposed decomposition methods on networks with irregular topologies. Numerical examples are given to demonstrate the applications of the proposed methods. © 2004 IEEE.published_or_final_versio

Performance improvement methods for burst-switched networks

In this paper, we present a performance model of optical burst switching (OBS) that can explain the degradation of OBS throughput performance when the control packet processing time increases. We then use the proposed performance model to investigate three feasible methods to improve OBS performance without significantly increasing the implementation complexity: addition of simple fiber delay lines (FDLs), random extra offset time, and window-based channel scheduling (WBS). Additional FDLs can eliminate the negative impact caused by the variation of the offset time between control packets and data bursts. The random extra offset time approach does not require any additional hardware and computational capability in the nodes. If higher computational capability is available, WBS in general can provide better throughput improvement than that of random extra offset time when FDLs are used in the nodes to compensate the processing time. Simulation results show that a combination of the proposed methods can significantly improve OBS performance. © 2011 Optical Society of America.published_or_final_versio

Performance model of deflection-routed multi-slot batch-transfer networks

published_or_final_versionWith the recently proposed multi-slot batch-transfer (MSBT) architecture, we can build optical packet switches using slow switching fabrics with reconfiguration time larger than the guard time between packets. Since MSBT switches can provide multichannel capability with no additional hardware, we propose to combine the multichannel and deflection routing approaches for packet contention resolution in MSBT networks. As there is no analytical performance model available, we derive the required model in this paper. Simulations show that the model is very accurate. © 2008 IEEE.link_to_subscribed_fulltextThe IEEE Global Telecommunications Conference (GLOBECOM 2008), New Orleans, LO., USA, 30 November-4 December 2008

On wavelength-routed networks with reversible wavelength channels

published_or_final_versio

Multicasting in deflection-routed all-optical packet-switched networks

Two multicast protocols are proposed for deflection-routed all-optical packet-switched networks. One scheme sends a deflected multicast packet back to the root node while the other sends it back to the deflection point Both schemes can be implemented using demonstrated optical signal processing technology. The performance of the two proposed multicast schemes are compared using Manhattan Street Networks. We found that the back-to-the-root-node scheme performed better than the back-to-the-deflection-node scheme. A hybrid approach can further improve the system performance.published_or_final_versio

Performance analysis of realistic optical time division multiplexed wavelength routed networks

Application of optical time division multiplexing (OTDM) in wavelength routed optical networks greatly enhances the flexibility of bandwidth assignment because OTDM provides time division sub-channels in a wavelength to match the processing speed of electronic devices. Different types of such OTDM wavelength-routed (OTDM-WR) networks, assuming different levels of sophistication of the OTDM technology, have been proposed. The performance of these OTDM-WR networks improves with the time-slot routing capability of the intermediate nodes of the network. However, as the transmission rate increases up to hundreds of gigabits per wavelength channel, electronic processing of the time slots limits the achievable performance of the OTDM-WR networks. All-optical signal processing can overcome the electronics bottleneck, but the available all-optical signal processing capability is rather limited and cannot yet utilize the full potential of time-slot routing. Even with such limitations, current technologies, such as fast wavelength converters and micro-electromechanical system (MEMS) optical switches, can significantly enhance the performance of existing wavelength-routed networks by adding the OTDM capability, albeit limited. We develop time-slot routing schemes that require fast wavelength converters only and study the performance of these schemes by simulations on Manhattan street networks and a network with the topology of the AT&T North America OC-48 fiber network.published_or_final_versio

A novel self-routing address scheme for all-optical packet-switched networks with arbitrary topologies

Pure all-optical packet-switched networks in which both header processing and packet routing are carried out in the optical domain overcome the bandwidth bottlenecks of optoelectronic conversions and therefore are expected to meet the needs of next generation high speed networks. Due to the limited capabilities of available optical logic devices, realizations of pure all-optical packet-switched networks in the near future will likely employ routing schemes that minimize the complexity of routing control. In this paper, we propose a novel self-routing scheme that identifies the output ports of the nodes in a network instead of the nodes themselves. The proposed address scheme requires single bit processing only and is applicable to small to medium size pure all-optical packet-switched networks with arbitrary topologies. Unlike traditional self-routing schemes, multiple paths between two nodes can be defined. Hierarchical address structure can be used in the proposed routing scheme to shorten the address.published_or_final_versio