Optical Burst Switching Networks Research Articles

Study and Development of Next-Generation Optical Networks

Next-generation optical networks are expected to provide tremendous capacity in order to support upcoming traffic increases. Many technologies are currently being developed for optical transport networks in order to increase throughput, improve energy efficiency and simplify network deployment. The most important problem in current optical networks is transmission of Internet protocol (IP) traffic. Regardless of the tremendous throughput with optical fibers, switching nodes still limit overall network performance. Recently, optical burst switching technology has been developed to overcome this problem. Optical burst switching combines the advantages of both circuit switching and packet switching networks and provides good performance in terms of packet data transmission. Even though optical burst switching networks provide a good mechanism for IP traffic transmission, overall performance is still limited because of access networks. Existing passive optical networks based on Ethernet technology are not fully compatible with optical burst switching, which results in bottlenecks on the border between transport and access networks. In this paper, we present a new method of optical wavelength time-division multiple access (OWTDMA) for passive optical networks. The proposed approach can provide outstanding scalability of network resources and can increase throughput of the optical access network. In addition, we propose implementation of OWTDMA in edge nodes of optical burst switching networks to eliminate bottlenecks between transport and access networks. Simulation results prove the advantage of our proposed approach.

Intelligent deflection routing in buffer-less networks.

Deflection routing is employed to ameliorate packet loss caused by contention in buffer-less architectures such as optical burst-switched networks. The main goal of deflection routing is to successfully deflect a packet based only on a limited knowledge that network nodes possess about their environment. In this paper, we present a framework that introduces intelligence to deflection routing (iDef). iDef decouples the design of the signaling infrastructure from the underlying learning algorithm. It consists of a signaling and a decision-making module. Signaling module implements a feedback management protocol while the decision-making module implements a reinforcement learning algorithm. We also propose several learning-based deflection routing protocols, implement them in iDef using the ns-3 network simulator, and compare their performance.

BHP flooding vulnerability and countermeasure

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.

A QoS‐supported controlled burst retransmission scheme in OBS networks

Burst retransmission can reduce data loss in burst contention in optical burst switching (OBS) core nodes. However, uncontrolled burst retransmission may significantly increase the network load and data loss probability, defeating the purpose of retransmission. Therefore, controlled retransmission should be studied to achieve reasonable retransmission, particularly to support quality of service (QoS) in OBS networks in which priority traffic exists. In this paper, we develop a QoS‐supported controlled retransmission scheme in OBS networks. Different from previous works in the literature, we set a different value for the retransmission probability at each contention for both high‐ and low‐priority bursts, set different retransmission probabilities for bursts of different priorities for QoS support, and propose a retransmission analytical model for OBS networks. We take into account the load at each link due to both the fresh and the retransmitted traffic and calculate the path‐blocking probability and the burst loss probability for high‐priority and low‐priority bursts to evaluate the network performance. An extensive simulation is proposed to validate our analytical model. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Performance analysis and improvement of loss recovery mechanisms in star OBS networks

In OBS networks, burst loss affects negatively the performance of the higher layers. Proactive loss recovery mechanisms, such as burst cloning, have the advantage of low burst delay but it suffers from low bandwidth utilization. However, reactive loss recovery mechanisms, such as burst retransmission, have the advantage of high bandwidth utilization but at the cost of high burst delay. In this paper, we present an analysis of this trade-off and we propose two new schemes to improve bandwidth utilization while keeping burst delay as low as possible in star OBS networks. The first scheme controls the retransmissions. The second scheme combines burst cloning and burst retransmission mechanisms. Analytical and simulation results show that the both schemes achieve high bandwidth utilization. The results confirm also that compared to basic burst retransmission scheme, the first scheme reduces burst delay only at moderate and high load, however, the second scheme reduce delay at every load.

A load balancing multi-path routing scheme based on effective voids for optical burst switching networks

Multi-path routing in the optical burst switching (OBS) networks can reduce the burst loss probability (BLP) by distributing the data burst traffic to multiple paths, compared with single path routing. Unlike the other multi-path routing schemes without considering the carrying capability of the routes, a new multi-path routing scheme based on effective voids (MPEV) is proposed to balance the load of multi-path and reduce the BLP in the paper. MPEV scheme first obtains the information on effective voids of the bottleneck link of multipath by sending a probe packet periodically. The effective voids can accommodate data bursts and accurately represent the available channel resource that is the main determinant of the BLP for OBS networks without optical random access memory. Then MPEV scheme distributes the burst traffic between an ingress node and an egress node to multiple link-disjoint paths by the ratio of the effective voids. More traffic is distributed to the path that has more effective voids, and vice versa. And the distributed amount is proportional to the effective voids of the bottleneck link. So MPEV scheme can balance the load of multi-path routes and can effectively reduce the BLP by avoiding the high load of a single path. And it is easy to implement and agilely adapt to dynamic network traffic. The performance of MPEV scheme is analyzed by queuing theory and is evaluated by simulation. The numerical results show that the proposed scheme can effectively reduce the BLP and balance the traffic load over multiple paths at the same time.

Performance evaluation of an OBS network as a IPP/M/W/W network

We develop an analytical method for calculating the burst loss probabilities in a tandem Optical Burst Switched (OBS) network with a bursty arrival process, depicted by an Interrupted Poison Process (IPP). The OBS network is modeled as a tandem network of loss nodes which is analyzed using single-node decomposition, whereby each node is studied in isolation as an IPP/M/W/W. For this, we need the departure process from an IPP/M/W/W which we obtain using binomial moment techniques. Performance evaluation of an OBS network shows that our method gives results which are closer to simulation results than a Poisson arrival process.

Hybrid offset‐time and burst assembly algorithm (H‐OTBA) for delay sensitive applications over optical burst switching networks

SummaryOptical burst switching (OBS) is the most favourable switching paradigm for future all‐optical networks. Burst assembly is the first process in OBS and it consists of aggregating clients packets into bursts. Assembled bursts wait for an offset time before being transmitted to their intended destinations. Offset time is used to allow burst control packet reserve required resources prior to burst arrival. Burst assembly process and offset‐time create extra delay in OBS networks. To make OBS suitable for real time applications, this extra latency needs to be controlled. This paper proposes and evaluates a novel offset time and burst assembly scheme to address this issue. Constant bit rate (CBR) traffic that has stringent end‐to‐end delay QoS requirements is used in this study. The proposed scheme is called hybrid offset‐time and burst assembly algorithm (H‐OTBA). The objective of the paper is achieved by controlling maximum burst transfer delay parameters of CBR. The proposed scheme was evaluated via network simulation. Simulation results demonstrate that, H‐OTBA has effectively reduced end‐to‐end delay for CBR traffic compared with current solutions. Copyright © 2014 John Wiley & Sons, Ltd.

Energy Efficient Parallel Optical Burst Switching (POBS) Networks

Greening the Internet has recently become one of the main challenges for the research community due to economic and environmental reasons. In this context, optical technology can offer an energy efficient solution. As such it is interesting to examine Optical Burst Switching (OBS) network that provides an avenue for reducing energy consumption by significantly reducing the amount of header processing in the core switch. A variant of OBS, which is known as Parallel Optical Burst Switching (POBS), takes this concept further by transmitting bursts in two dimensions: the wavelength dimension and the time dimension. Consequently, this study investigates the power consumption in both the OBS and POBS technologies when used in the core network. The simulation results show that in the core network, the use of POBS can provide significant saving in energy as compared to the use of OBS. Furthermore, the use of POBS can lower the power consumption and the number of packets dropped in the network when appropriate parameter settings are used, particularly the burstification time and waveband granularity.

A well-aware resource reservation strategy TAW+ in the Optical Burst Switched System

For the Optical Burst Switched (OBS) System, a new resource reservation strategy TAW+ is presented in the Intra-Domain Network Statue Model (INSM). By promptly using the control signal channel to update the INSM, better decisions are made in selecting optical path and assigning wavelength at each OBS network edge node, which can make the node to avoid reserving those being used link resources. Besides, a time slot is introduced to detect the latent collision, which not only can achieve the goal in preventing the forthcoming collision effectively, but also can better support multi-priority QoS. Furthermore, Virtual Configuration Table (VCT) at the network core node is further proposed to resolve collisions without bandwidth wastage. The analysis and simulation results verify the feasibility of the proposed strategy in the OBS network, show the enhancing of the network state awareness capability at edge node in lack of the optical conversion capability and optical buffer, and improve the effect on the data burst drop probability and QoS supports.

Group Scheduling for MultiChannel in OBS Networks

Group scheduling is a scheduling operation of optical burst switching networks in which the burst header packets arriving in each timeslot will schedule their following bursts simultaneously. There have been many proposals for group scheduling (such as OBS-GS, MWIS-OS and LGS), but they consider mainly to schedule the arriving bursts which have the same wavelength on an output data channel. Another suggestion is GreedyOPT which considers the group scheduling for multichannel with the support of full wavelength converters, but it is not optimal. This article proposes another approach of group scheduling which is more optimal and has a linear complexity.

Optical Multicast over OBS Networks: An Approach Based on Code-Words and Tunable Decoders

Optical Multicast over OBS Networks: An Approach Based on Code-Words and Tunable Decoders

Optical Multicast over OBS Networks: An Approach Based on Code-Words and Tunable Decoders

Optical Multicast over OBS Networks: An Approach Based on Code-Words and Tunable Decoders

The Contention Resolution in OBS Network

Burst contention occurs when attempting to transmit several optical bursts at the time into the same core router output port. This is a shortcoming of the Optical Burst Switching (OBS) networks and for this reason it has been challenging to implement the OBS mode into the transport networks so far. This problem can be solved applying various contention resolution strategies at core nodes (fiber delay lines, wavelength conversion or deflection routing). The following question arises: how does data transmission through the OBS network quality depend on using such strategy combination in the core node? For these reasons an analytical model has been created to find out what impact a joint application of various contention resolution strategies has on the data transmission quality. An algorithm has been proposed for the burst service in the OBS core router when a contention arises. The authors suggest applying burst segmentation only for the lower priority bursts, reducing the lower priority data losses in the case of mixed priority burst incoming flow. Every additional burst collision resolution strategy increases the time spent at the node however, so it is highly important to determine by means of simulations the optimal amount of resources needed at the core node. DOI: http://dx.doi.org/10.5755/j01.eee.20.6.7288

A Novel Mechanism for Contention Resolution in Parallel Optical Burst Switching (POBS) 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).

A Dual Price-Based Congestion Control Mechanism for Optical Burst Switching Networks

A dual price-based congestion control (DPCC) mechanism for optical burst switching (OBS) networks is proposed in this paper, which can achieve an optimal rate-reliability tradeoff by allocating proper network traffic and resources based on the idea of network utility maximization (NUM). The DPCC uses the congestion and reliability prices and feedback information to dynamically adjust the users’ data sending rate and the end-to-end data transmission reliability in an OBS network. The performance of DPCC is evaluated and analyzed through simulations. Results verify that DPCC works very well in terms of its convergence and optimality. Moreover, compared with TCP, DPCC can achieve a maximum network utility, a parameter which can be used to reflect the overall user satisfaction degree in a network. DPCC is scalable due to its distributed nature.

SPECTRAL THREAT IN TCP OVER OPTICAL BURST SWITCHED NETWORKS

Exponential increase in the number of online users has increased over the years posed a demand for high speed core architecture for the internet. The Optical Burst Switching (OBS) is a new switching architecture that efficiently utilizes the bandwidth of the optical layer. It offers all-optical switching as there is no Optical-Electronic conversion at any intermediate switching node. It is one of the three optical switching architectures, while others being Optical Circuit Switching (OCS) and Optical Packet Switching (OPS). The basic switching entity of OBS is a burst which posses an intermediate granularity between a packet and the amount of optical data in a circuit. The OBS architecture merits the shortcomings of the other two optical architectures namely OCS and OPS. This efficient core networking architecture, suffers from various security vulnerabilities. This paper proposes a novel security threat namely the spectral threat. It is a threat that affects only multicast capable nodes. Multicast Capable nodes are those nodes that are capable of multicasting an optical data. The wavelength of the optical data burst is altered resulting in flooding of data to a particular outgoing channel and ultimately blocking the channel. The attack results in losses thereby reducing the burst throughput and increasing the burst latency. The paper further summarizes other potential threats affecting normal nodes and Multicast Capable nodes for TCP over OBS networks.

Optical Multicast over OBS Networks: An Approach Based on Code-Words and Tunable Decoders

Optical Multicast over OBS Networks: An Approach Based on Code-Words and Tunable Decoders

Study on Pre-Deflection Routing in OBS Network Based on Congestion Avoidance

Burst contention is the key issue to solve for optical burst switching (OBS), deflection routing is researched as an effective contention resolution approach. A pre-deflection Routing (CAPDR) algorithm based on Congestion Avoidance is proposed in the paper, using periodic feedback network congestion information, the algorithm deflects in advance parts of the bursts in some probability. Compared with the traditional shortest path deflection routing, the new algorithm can avoid congestion and also balance the load of the network. Simulation results show that the proposed algorithm outperforms shortest path deflection routing in terms of the burst loss ratio (BLR), throughput and average link utilization.

EVALUATION OF HIDDEN MARKOV MODEL BASED ADAPTIVE PROVISIONING OF OPTICAL BURST SWITCHING NETWORKS AMENABLE FOR UPGRADATION TO GREEN FLEXIGRID NETWORKS

Catering to the evolving bandwidth-on-demand applications requires flexible provisioning architectures that ensure fairness to both high end and low end users of internet. Dynamic classification of network path s into long and short, based on traffic dependent connecti on holding times and a wavelength allocation from different subsets for these categories is a necessi ty for implementing energy saving hybrid switching, loss recovery and flexi grid bit rate variable schemes. Therefore, this study evaluates such a scheme of d ynamic classification based on HMM predicted connection-holding times with tightly integrated adaptive burst sizing and segregated wavelength allocation for lon g and short categories. Simulation study of a 28 no de OBS network shows that this coupled scheme reduces delays and results in throughput improvement of 67% for long and 12% for short traffic over schemes tha t employ adaptive burst sizing based on number of a ctive traffic flows and independent wavelength assignment schemes.