Double-link failure protection algorithm for shared sub-path in survivable WDM mesh networks

We propose a novel shared sub-path protection (SSPP) algorithm to protect the double-link failures in wavelength division multiplexing (WDM) mesh networks. SSPP segments the primary path into several equal-length sub-paths and searches two link-disjoint backup paths for each sub-path. When computing the paths, SSPP considers the load balance and the resource sharing degree, so that the blocking ratio can be effectively reduced. The simulation results show that SSPP not only can completely protect the double-link failures but also can make the tradeoffs between the resource utilization ratio (or blocking ratio) and the protection-switching time.     

Recovery schemes for different distributed connection management in generalized multi-protocol label switching networks

As the wavelength division multiplexing (WDM) technology matures and the demands for bandwidth increase, survivability becomes more and more important in generalized multi-protocol label switching (GMPLS) controlled intelligent optical networks (IONs). There are great interests to study the performance of restorability under one certain connection management strategy. And studies in the problem of providing recovery from link failures under two different resource reservation schemes, forward reservation protocols (FRPs) and backward reservation protocols (BRPs), are presented. They are examined from the point of view of connection blocking probability, restorability and average recovery time. The two different connection management schemes and the survey of different recovery schemes are first presented. The performance of these recovery strategies is analyzed and compared both through theoretical analysis and simulation results. The main stressed idea is that using BRPs gives the best performance in terms of restorability and blocking probability in restorable GMPLS networks.     

Effects of the switching time in OPS/OBS networks

In this paper we present an analytical model, which considers the effects of the switching time on the network performance in service differentiated optical packet/burst switching (OPS/OBS) networks. Our results indicate that the switching time must be less than 10 % of the packet/burst duration in order to avoid any significant reductions in the network performance. Furthermore, regarding a network with full     

Optimal design of virtual topology reconfiguration in WDM optical networks

Virtual topology of WDM optical networks is often designed for some specific traffic matrix to get the best network performance. When traffic demand imposed on WDM optical networks changes, the network performance may degrade and even become unacceptable. So virtual topology need to be reconfigured. In previous works, virtual topology is reconfigured to achieve the best network performance, in which a large number of lightpaths need to be set up or torn down. In this paper, we try to get a tradeoff between the network performance and traffic disruption (or implementing cost). The problem of virtual topology reconfiguration for changing traffic patterns is formulated as an optimization problem and a mixed integer linear programming (MILP) algorithm is presented. Numerical results show that a large cost reduction of reconfiguration can be achieved at the expense of network performance.     

Performance analysis of an integrated scheme in optical burst switching high-speed networks

A new integrated scheme based on resource-reservation and adaptive network flow routing to alleviate contention in optical burst switching networks is proposed.The objective of the proposed scheme is to reduce the overall burst loss in the network and at the same time to avoid the packet out-of-sequence arrival problem.Simulations are carried out to assess the feasibility of the proposed scheme.Its perfor- mance is compared with that of contention resolution schemes based on conventional routing.Through extensive simulations,it is shown that the proposed scheme not only provides significantly better burst loss performance than the basic equal proportion and hop-length based traffic routing algorithms,but also is void of any packet re-orderings.     

Dynamic protected lightpath provisioning in mesh WDM networks

This paper investigates the problem of dynamic protected lightpath services provisioning in optical mesh networks employing wavelength division multiplexing (WDM). A variety of schemes for dynamic protected services provisioning have been proposed, supporting a range of tradeoffs among restoration speed, capacity efficiency, and scalability. In this paper, we propose a novel scheme, called p-cycles-based maximum protected working capacity envelope (PC-MPWCE), which can offer an attractive combination of features: ring-like speed, mesh-like capacity efficiency, and good scalability. To evaluate the performance of PC-MPWCE, we compare it via simulation with 1 + 1 automatic protection switching (APS) and two well-known shared backup path protection (SBPP) on NSFNET. Our simulation results show that PC-MPWCE can achieve much better blocking performance than 1 + 1 APS, and perform the similar blocking performance and capacity efficiency as SBPP.     

Improved adaptive-threshold burst assembly in optical burst switching networks

An improved adaptive-threshold burst assembly algorithm is proposed to alleviate the limitation of conven- tional assembly schemes on data loss and delay.The algorithm will adjust the values of assembly factors according to variant traffic regions.And the simulation results show that,by using the adaptive-factor adaptive assembly scheme,the performance of networks is extensively enhanced in terms of burst loss probability and average queuing delay.     

Asymmetrical off–on switches for crosstalk reduction in switching networks

An off–on switching scheme is introduced which blocks a waveguide path in the passive off-state and transmits the signal in the active on-state. The operating principle is based on the self-diffraction of a narrow guided beam when it escapes from a waveguide with two-dimensional confinement into a region of appropriate length with basically one-dimensional confinement. In particular, a remaining interface of the initial waveguide superimposes reflection, which in sum results in a very efficient asymmetrical blow out of the guided power. In the active on-state, low-loss waveguiding is sustained when an electrode causes an appropriate refractive index change, e.g., due to the thermo-optical effect. Thus, the signal is received in the output waveguide, the identical counterpart of the input guide. The switching behaviour is almost binary with minimal wavelength dependence. This makes the device useful for switching and modulation in a multi-wavelength optical network. For a realistic polymeric waveguide configuration, simulations indicate on-off signal ratios of >30 dB. This satisfies the requirements for crosstalk reduction in switching networks.     

A new burst assembly technique for supporting QoS in optical burst switching networks

This letter proposes a new burst assembly technique for supporting QoS in optical burst switching (OBS) networks. It consists of the adaptive-threshold burst assembly mechanism and QoS-based random offset-time scheme. The assembly mechanism, which is fit well to multi-class burst assembly, not only matches with IP QoS mechanism based on packet classification, and also utilizes fairly and efficiently assembly capacity. Based on token-bucket model and burst segment selective discard (BSSD), the offset-time scheme can smooth the traffic to support OBS QoS. The simulation results show that the technique can improve the performance in terms of packet loss probability (PLP).     

Analysis of Optical Equalization in WDM System

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