Xiaolong Yang

A novel fault detection method based on probe cycle cover in mesh optical burst switching networks

An efficient fault detection method, employing cycle cover theory, is proposed. Three classic cycle finding algorithms are compared in terms of cost-saving and feasibility. We through computation and statistic find that our proposed method is economical and practical.

Buffer-based latest available unscheduled channel (BLAUC) : An efficient scheduling algorithm for OBS networks

Optical burst switching (OBS) is considered as a promising paradigm for the next generation Internet. In the OBS networks, the data channel scheduling algorithm is one of key issues. The object of channel scheduling algorithms is to improve the performance of burst dropping probability and to decrease the complexity of computation. Based on the idea, a new scheduling algorithm, called buffer-based latest available unscheduled channel (BLAUC), is proposed in the paper. Its basic idea can be depicted as follows: to buffer more than one burst control packets (BCP) at first, and then to schedule the corresponding data bursts (DB) by the order of burst arrival time. The max buffer time is an important parameter in the BLAUC algorithm. It is deduced in the paper that the optimisation of the max buffer time is the maximum difference of offset time in the core node. Based on latest available unscheduled channel (LAUC) algorithm, BLAUC only adds buffering and changes the scheduling order. So BLAUC is as simple as LAUC. And adopting the policy of scheduling by burst arrival time, BLAUC has better performance than LAUC in terms of burst dropping probability. Simulation results show that BLAUC not only outperforms LAUC in terms of burst dropping probability, but also outperforms LAUC-VF in the condition of enough buffer time.

The Economics-based Pricing and Request Scheduling Scheme for Lightpath Resources of Grid-enabled Optical Networks

Recently, some solutions (such as UCLP, GARA and GridJIT, etc.) have been proposed to manage optical network resources as other grid resources. However, most of them do not consider optical network resources as general grid resources to schedule and share, and fatally they are not compatible with the new developed resource management framework WSRF (Web Service Resource Framework) within the global grid architecture OGSA. Besides, there are some other problems in the resources scheduling and sharing. This paper presents the economic-based grid-enabled management architecture for lightpath resources GRACIE, which improved the GRACE with the ability of scheduling and managing optical resources. Based on GRACIE, it proposed lightpath resource pricing algorithm and lightpath request scheduling scheme. Finally, we demonstrated their effectiveness by experiments on GridSim.

TPDR: an efficient deflection routing algorithm to resolve burst contention in optical burst switching networks

The burst contention has a strong impact on the performance of optical burst switching (OBS) network, and currently, various contention resolution schemes have been proposed from time domain, space domain and wavelength domain, respectively. Among the schemes, the deflection routing is more attractive, which can loosen the requirement of optical buffer in capability and quantity. With deflection routing, the contending burst is rerouted to an available port other than the intended output instead of being dropped. However, when the traffic load is high, there should not be only more contentions but also frequent deflection routings, some of which might aggravate the network status. To improve the status, this paper proposes the tunable-parameter deflection routing (TPDR) algorithm, which can control the deflecting operation of a contending burst by a tunable-parameter, i.e., deflection probability, which is settled by the priority and traffic load of contending burst, and search the optimum deflection path in terms of the burst loss probability and the path length. The simulation results show that it can improve the overall BLP and the BLP of each individual priority, and alleviate the negative effect of the offset-time deficit on QoS guarantee.

The architecture and implementation of multicast-ware GMPLS-based OBS networks

Since IP-over-WDM has become a natural choice for the next generation backbone networks. It is more eminent to implement efficient multicast in WDM networks. A light-tree has been defined to support multicast sessions in WDM layer, it construct a point-to-multipoint light-paths from a source to multiple destinations and can be implemented by power-splitters. With the mature of power-splitters, there is a need to develop framework at higher layers to efficiently use the multicast available at WDM layer. In this paper, we concentrate on OBS-based multicast, new node models supporting WDM multicast are proposed. Then base on the models, we put forward novel implementation architecture of GMPLS-based OBS network to support multicast services, which maps an IP multicast-tree onto a multicast LSP that are connected to form a WDM light-tree. Two salient features of the architecture are: multicast LSP is constructed by data-driven; and the inter-operation between GMPLS framework and OBS. Finally, we discuss the performance of the proposed architecture.

A general framework for GMPLS-based OBS networks

Researches about infrastructure and applications of next generation Internet is one of the most comprehensive research fields in recent years, IP over WDM is envisioned as the best candidate for next generation Internet. Generalized Multi-Protocol Label Switching (GMPLS) was proposed as an excellent control plane technology for the integration of IP and WDM, which can achieve the on-demand provisioning and management of network resources. And optical burst switching (OBS) is considered as a promising switch paradigm for next generation Internet, which can not only provide statistical multiplexing of network bandwidth resources, but also circumvent the bottleneck of electronic switching effectively. Therefore, how to integrate GMPLS into OBS network and use GMPLS to improve performances of OBS networks becomes an important research direction and have received comprehensive concerns from many research institutions and organizations. This article proposes a new kind of OBS network namely GMPLS-based OBS network, describes its general framework and some work mechanisms, and gives node functional modules and the control plane software components. Some issues related to network management also are discussed.

Performance of DiffServ-capable OBS networks based on pipeline buffering system

In this paper, we integrate the pipeline buffering mechanism with the DiffServ-capable OBS to schedule data burst (DB) at core nodes. And we improve a DiffServ-capable virtual scheduling technique (DiffServ-VST) to adapt our scheme. For performance evaluation, we propose a new model to revise the classic Erlang-B formula for calculating burst loss probability in OBS environment: the LAUC-VF-ed M/D/K/K. The simulation results shows that lower packet loss probability and higher link utilization is obtained when traffic load is less than 0.8 by using our scheme. However, the extra end to end delay of AF and BE is brought by pipeline buffer.

An optimization-based N:1 multi-class optical burst assembly mapping technique to support QoS

In IP network, the coarse packet classification is a scalable QoS solution. Similarly, it can also be utilized to OBS network because of its scalability. However, the OBS network can support only few priorities of optical burst due to the limitation of current optical device and signal process technology. Hence, in an edge node of OBS networks, the bursts are usually assembled through the many-to-one composite class burst (CCB) assembly technique, e.g., N:1-CCB. Currently, the QoS issue in OBS is as active as that in IP networks. The burst assembly has a great impact on the QoS support of OBS network. According to the study of the N:1-CCB burst assembly technique, there are two aspects related with the scalable QoS support, i.e., the mapping relationship and the assembly resource allocation. This paper simultaneously focuses the two aspects, and based on the linear optimization theory, proposes a novel assembly mapping mechanism, i.e. Optimized TQ-MAP, which most important feature is adaptivity. Based on nonlinear programming and differential calculus, it allocates the burst assembling capacity between classes fairly, efficiently and differentially, and matches IP QoS requirement with OBS QoS capacity as possible as it can. The simulation results show that Optimized TQ-MAP is more adaptive, and can efficiently guarantee the coherence of QoS support from IP to OBS.

A data channel scheduling algorithm based on burst migration for optical burst switching networks

Currently optical burst switching (OBS) has been regarded as the most promising backbone networking technology for the next-generation Internet. In the OBS network, the data channel scheduling is one of key problems. Bandwidth efficiency and QoS support are its two concern focuses. However, the existing algorithms pay more attention to bandwidth efficiency. In this paper, we develop an efficient data channel scheduling algorithm, called BM-VF-SBD. It effectively integrates several mechanisms (i.e., void filling, burst migration and selective burst discard) to reduce the bandwidth fragment and support QoS. Its basic idea is in that a new burst is scheduled by migrating some bursts to other channels if none of voids in any channels can accommodate it; otherwise repeating the above processes after selectively dropping some bursts. Meanwhile under an effective data structure, such as the balanced binary search tree, its computational complexity will be o[(2w+1)log w] at most, and be close to LAUC-VF and ODBR. In the proposed algorithm, burst migration plays a key role in the improvement of bandwidth efficiency while selective burst discard has great effects on the two sides. The simulation results show that it performs much better than LAUC-VF and ODBR in burst loss probability (overall or individual) and bandwidth fragment ratio.

MIS-LB: a QoS routing algorithm with min-sharing interference and load balancing based on nonlinear path distance

As known, the QoS routing under multiple constraints, which can be additive, multiplicative and concave, is a NP-complete problem, and is difficult to get a polynomial-time solution. Currently, many heuristic algorithms have been proposed to solve this problem, where the path distance usually acts as the most important factor during the routing decision-making. However, most of heuristic algorithms are based on linear path distance, which has the greatest shortcoming, i.e., the search of feasible solutions is inefficient. Besides, they also consider the link sharing interference and load balancing. To improve their performance, this paper proposes a novel QoS routing for multiple constraints based on the nonlinear path distance, which is called MIS-LB. At first, this paper represents the additive and multiplicative QoS metrics in the uniform metric, i.e. the nonlinear path distance. Then, the paper also brings the link sharing and load balancing into the uniform metric. Based on the shortest-first criterion, MIS-LB can not only find feasible paths as the normal routing algorithm (e.g., Dijkstra algorithm), but also adjust the link sharing, and balance the network loads between multiple feasible paths. So compared with TAMCRA and H_MCOP, the simulation results show that MIS-LB can further improve network performance.