Performance analysis and simulation of a novel OBS network architecture

Among the promising solutions for next generation Internet backbones, one can consider the optical burst switching (OBS) technology. The deployment of the OBS technology needs to address dimensioning and resources optimization issues that constitute an essential task in the development of OBS services. In this paper, we propose a QoS-based approach to address these issues in the development of OBS networks. An analytic model is developed for network resources dimensioning and optimization problems' formulation. A simulation model is developed to validate the proposed approach, and to study the impacts of some key input system parameters on the optimal network configuration.

Next-generation high-speed Internet backbone networks will be required to support a broad range of emerging applications which may not only require significant bandwidth, but may also have strict quality of service (QoS) requirements. Furthermore, the traffic from such applications are expected to be highly bursty in nature. For such traffic, the allocation of static fixed-bandwidth circuits may lead to the over-provisioning of bandwidth resources in order to meet QoS requirements. Optical burst switching (OBS) is a promising new technique which attempts to address the problem of efficiently allocating resources for bursty traffic. In OBS, incoming data is assembled into bursts at the edges of the network, and when the burst is ready to be sent, resources in the network are reserved only for the duration of the burst. The reservation of resources is typically made by an out-of-band one-way control message which precedes the burst by some offset time. By reserving resources only for the duration of the burst, a greater degree of utilization may be achieved in the network. This book provides an overview of optical burst switching. Design and research issues involved in the development of OBS networks are discussed, and approaches to providing QoS in OBS networks are presented. Topics include: - Optical burst switching node and network architectures - Burst assembly - Signaling protocols - Contention resolution - Burst scheduling - Quality of service in OBS networks

Parallel Optical Burst Switching (POBS) is a variant of Optical Burst Switching (OBS) which is proposed as a new optical switching strategy for Ultra-Dense Wavelength Division Multiplexing (U-DWDM) to support the enormous bandwidth demand of the next generation Internet. As opposed to OBS, POBS transmits bursts in two dimensions: the wavelength dimension and the time dimension. POBS network uses an one-way resource reservation mechanism to set up the resources for each data burst transmission. The use of this mechanism may cause bursts to contend for the same resources at the same time at core (intermediate) nodes of the network. Therefore, the performance of POBS networks depends on the contention resolution policies to reach acceptable levels for bandwidth usage. These policies may increase both the cost and complexities of the core nodes in POBS networks. Most literatures on OBS networks apply contention resolution at the core nodes based on reactive strategies that are activated after contention takes place in core nodes. This study proposes the use of a proactive contention resolution technique at ingress nodes of POBS network as well as reactive contention resolution technique at core nodes for reducing the probability of burst drop in the network in order to increase the performance of the network. The simulation results show that the use of POBS network with the proposed Reactive Odd/Even Node ID Wavelength Assignment Technique (POBS-ROENIDWAT) shows a better performance in terms of reduced data loss rate and increased throughput compared to the performances of both POBS network with Sequential Wavelength Assignment Technique (POBS-SWAT) and OBS network with Burst Segmentation (OBS-BS).

In this paper, we propose a protocol architecture and quality of service (QoS) supporting algorithms for optical Internet based on optical burst switching (OBS) technology. Firstly, the function of each layer of the protocol architecture and the formats of control packets are defined in order to adopt GMPLS to the control plane of OBS. Then, the offset time decision (OTD) algorithm to cooperate with the proposed protocol architecture is designed for optical Internet. A new burst loss formula taking into account the effect of offset time is introduced to design the OTD algorithm. This algorithm can decide on the appropriate “priority-offset” time according to the required QoS by using the reversed equation of the so-called heuristic loss formula (HLF) which is approximated as a proportional equation of our new loss formula. Finally, we propose a CAC algorithm based on the OTD algorithm for the purpose of increasing the availability of wavelength resources and supporting the QoS of established connections in optical Internet. The performance of the proposed algorithms is evaluated in terms of burst loss rate and the number of connections through simulation.

A crucial issue in optical burst switching (OBS) networks is burst loss caused by resource contention. As a result, many methods are currently being proposed to reduce burst loss rate. These methods can be summed up into two categories: burst scheduling algorithms and contention resolutions. Both categories of methods can reduce burst loss rate to a certain degree. However, to make OBS to become a viable solution, the burst loss rate needs to be further reduced. Furthermore, almost all methods ignore the fact that an unfortunately scheduled, locally generated single-hop burst could block a number of future incoming transit bursts, though the burst just travels to its next downstream node. This phenomenon becomes more evident when links are heavily loaded in mesh OBS networks. To eliminate contention caused by single-hop traffic completely, this paper proposes a novel transfer mode called packet calking by differentiating between single-hop traffic from multihop traffic for OBS networks. An analysis model is developed to evaluate the performance of packet calking. Theoretical results are validated through extensive simulations in both ring and mesh networks. These results show that packet calking outperforms the transfer mode without packet calking in terms of burst loss rate and link utilization.

Optical burst switching (OBS) is a switching technology that can efficiently operate in the optical core network using WDM technology and can also develop the future optical internet. The OBS switching technology presents a trade-off between the two switching technologies: optical circuit switching (OCS) and optical packet switching (OPS). This switching approach increases resource utilization compared with OCS technology and avoids the technological barriers of OPS networks. In OBS networks, many packets are assembled into one data burst at the edge node and a burst header packet (BHP) is sent before the burst transmission by an offset time in order to reserve the required resources in core nodes. This can cause security issues in the network and more specifically denial of service attacks that can occur if a source node is compromised. In this paper, we study a specific denial of service attack which we refer to as "BHP flooding attack", which prevents legitimate traffics from reserving the required resources at intermediate core nodes. We also propose the design of a reconfigurable BHP flooding countermeasure module that allows to counter against this type of attacks in an OBS network.

Optical burst switching (OBS) supports IP-over-photonics for future QoS-supporting Internet through combining advantages of electronic control processing and optical transmission. The resource reservation is critical for OBS. In this paper we examine optical burst switching (OBS) reservation process and discuss the most important parameters and their impact on the performance of the reservation process. A general framework for its modeling and analysis is presented. We model OBS reservation using queueing networks. Our framework and model cover all aspects of OBS reservation process including control packet arrival, offset time assignment. control packet processing, optical switch matrix setup, data burst arrival and transmission. Current models and analysis only consider offset time assignment and data burst arrival and transmission its OBS reservation. Further we show that even though widely assumed and used, conservation law does not hold generally for average burst loss probability for reservation processes which support multiple priority classes.

Optical burst switching (OBS) is a new optical switching paradigm where traffic can be switched and groomed at a lower level compared to optical switched circuit (OCS). While OCS is useful in carrying highly aggregated long-lived streams that require absolute quality of service (QoS) guarantees, OBS has a role in efficiently carrying bursty best-effort traffic. In this paper, we investigate further the comparative goodput and bandwidth efficiency of OBS and OCS using, on one hand, an adaptive deflection OBS routing that aims at minimizing the burst loss rate and, on the other hand, a routing and wavelength OCS strategy using the best possible routing paths for minimizing the blocking rate.

The prospects of Optical Burst Switching (OBS) as a cost-effective switching paradigm for future all-optical transport networks could greatly benefit from avoiding the use of complex and expensive all-optical wavelength converters at the network nodes. However, contention resolution is essential to achieve reasonable bandwidth utilization efficiency in OBS networks and replacing the wavelength converters by Fiber Delay Line (FDL) buffers requires huge numbers of FDLs and large space switches, thus also rendering complex network nodes. This paper proposes combining the use of a priority-based wavelength assignment and burst scheduling strategy at the ingress nodes, which minimizes the probability of contention, with the use of shared FDL buffers at the core nodes to resolve the unavoidable contentions. The objective is to design OBS networks employing only moderate numbers of simple FDL buffers while matching the performance of a network using full-range wavelength converters. Simulation results using a reference network topology show that this goal is feasible. Moreover, the FDL buffer requirements are shown to depend on the offered traffic load, the number of wavelengths per link, and the maximum burst delay at the ingress node.

Optical burst switching (OBS) is proposed as a high-speed, flexible, and transparent technology. It is thought to be the best way to adapt the bursty IP traffic over optical wavelength division multiplexing (WDM) networks. OBS technology facilitates the efficient integration of both IP and WDM. It provides statistical multiplexing gains and avoids long end to end setup time of traditional virtual circuit configuration. However, there are still a lot of challenges, one of which is burst contention. Owing to the fact that random access memory like buffering is not available in the optical domain at present, there exists a real possibility that bursts may contend with one another at a switching node. Many contention resolutions are proposed. The major contention resolutions in literature are wavelength conversion, fiber delay lines, and deflecting routing. In this paper, a new data burst scheduling scheme, called group scheduling based on control-packet batch processing (GSCBP) was proposed to reduce burst contention. Like transmission control protocol, GSCBP has a batch processing window. Control packets which located in the batch processing window are batch processed. A heuristic scheduling algorithm arranges the relevant bursts' route based on the processing result and the network resource. A new node architecture supporting group scheduling was presented. The GSCBP algorithm is combined with wavelength converter and/or fiber delay lines which is shared by some data channels. Meanwhile, an extended open shortest path first (E-OSPF) routing strategy was proposed for OBS. Both GSCBP and E-OSPF are introduced into 14-node national science foundation network by means of simulations. The ETE delay, burst blocking probability, as well as burst dropping probability were attained. Results show that the GSBCP lead to the higher-priority traffic drop rate decrease one order of magnitude, if drop rate and ETE delay of lower priority traffic is sacrificed.

Optical Burst Switching (OBS) is an optical switching technology capable of supporting large demands for bandwidth in optical backbones with Wavelength Division Multiplexing (WDM). This paper presents an OBS simulation model for the discrete event simulator OMNeT++. The performance of this model is compared with the performance of the well-known INET simulation model for IP networks. Both models show similar performance results. The OBS model is faster but uses more dynamic memory.

The fast development of translucent Optical Burst Switching (OBS) technology, which employs multiple wavelengths per fiber, increases the size (i.e., the number of ports) as well as the cost and power consumption of Optic Cross-Connects (OXCs). This paper studies the impact of OBS network parameter settings, where switching is performed at the Waveband Switching (WS) granularity using an end-to-end grouping method to reduce the number of lightpaths and switch ports. The simulation results illustrate that using OBS networks with WS by the suitable parameter settings, namely the Burstification Time (BT) and waveband granularity, offers considerable energy savings in the core network compared to using an OBS network without WS, where overall power consumption is decreased by maximizing BT values and waveband granularity.

Optical burst switching (OBS) is regarded as a promising optical switching paradigm for next generation optical Internet. More and more real-time traffic is transported by IP and it is important for OBS to support real-time traffic. Based on the delay analysis of OBS networks, a pipeline scheme is proposed to reduce the delay and efficiently support real-time traffic for OBS networks in the paper. When real-time traffic is transported in the core nodes of the established pipeline and its burst head packet can not need to be processed. So the pipeline scheme reduces the offset time and delay of realtime traffic. The simulation result shows that the pipeline scheme effectively reduces the end-to-end delay of real-time traffic in the OBS networks.

Optical Burst Switching (OBS) is a promising switching technology for the next generation all-optical networks. An OBS network without wavelength converters and fiber delay lines can be implemented simply and cost-effectively using the existing technology. However, this kind of networks suffers from a relatively high burst loss probability at the OBS core nodes. To overcome this issue and consolidate OBS networks with QoS provisioning capabilities, we propose an absolute QoS differentiation scheme, called Absolute Fair Quality of service Differentiation (AFQD), which is based on a wavelength partitioning scheme, called Optimization Topology-aware Wavelength Partitioning scheme (OTWP). AFQD is the first absolute QoS provisioning scheme that guarantees loss-free transmission for high priority traffic inside the OBS network. Simulation results show that AFQD not only guarantees loss-free transmission for high priority traffic but also substantially decreases the loss probability of best effort traffic to a remarkable level compared to the existing schemes.

Optical burst switching (OBS) has been proposed as the next generation optical network for grid computing. In this paper, we envision a heterogeneous Grid served by an Optical Burst Switching framework, where grid traffic co-exists with IP and/or a 10 GE based traffic to achieve economy of scale. This paper addresses the latency that Grid jobs experience in OBS networks. The injection of jumbo size grid jobs can potentially affect the latency experienced by IP/10GE traffic. Simulation results have shown that in Grids served by an optical burst switch, grid jobs consistently have lower latency than co-existing IP/10GE traffic, with a slightly elevated latency of IP/10GE traffic when the size of grid jobs increases. We conclude that given the fact that OBS can efficiently handle the enormous amount of bandwidth made available by DWDM technology, Grid over Optical Burst Switching is a cost effective way to provide grid services, even for latency sensitive grid computing applications.