Burst Loss Reduction Using Fuzzy-Based Adaptive Burst Length Assembly Technique for Optical Burst Switched Networks

The optical burst switching (OBS) paradigm is perceived as an intermediate switching technology prior to the realization of an all-optical network. Burst assembly is the first process that takes place at the edge of an OBS network.  It is crucial to the performance of an OBS network because it greatly influences loss and delay on such networks.  Burst assembly is an important process while  burst loss ratio (BLR) and delay are important issues in OBS.  In this paper, an intelligent burst assembly algorithm called a Fuzzy-based Adaptive Length Burst Assembly (FALBA) algorithm that is based on fuzzy logic and tuning of fuzzy logic parameters is proposed for OBS network. FALBA was evaluated against itself and the fuzzy adaptive threshold (FAT) burst assembly algorithm using 12 configurations via simulation. The 12 configurations were derived from three rule sets (denoted 0,1,2), two defuzzification techniques (Centroid [C]and Largest of Maximum[L]) and two aggregation methods (Max[M] and Sum[S]) of fuzzy logic.  Simulation results have shown that FALBA0LM has the best BLR performance when compared to its other configurations and the FAT. However, with respect to delay, FAT only outperforms all configurations of FALBA at low loads (0.0-0.4) but the performance of FAT also decreases as the load (0.4-1.0) increases. Therefore, at high loads (0.4-1.0)  FALBA2CS has the best delay performance. Our results deduce that FALBA0LM can be use

Dynamic threshold-based algorithms for communication networks

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 68-72.A need to use dynamic thresholds arises in various communication networking scenarios under varying traffic conditions. In this thesis, we propose novel dynamic threshold-based algorithms for two different networking problems, namely the problem of burst assembly in Optical Burst Switching (OBS) networks and of bandwidth reservation in connection-oriented networks. Regarding the first problem, we present dynamic threshold-based burst assembly algorithms that attempt to minimize the average burst assembly delay due to burstification process while taking the burst rate constraints into consideration. Using synthetic and real traffic traces, we show that the proposed algorithms perform significantly better than the conventional timer-based schemes. In the second problem, we propose a model-free adaptive hysteresis algorithm for dynamic bandwidth reservation in a connection-oriented network subject to update frequency constraints. The simulation results in various traffic scenarios show that the proposed technique considerably outperforms the existing schemes without requiring any prior traffic information.Toksöz, Mehmet AltanM.S

A new adaptive burst assembly algorithm for OBS networks considering capacity of control plane

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical references leaves 55-57.Recent developments in wavelength-division multiplexing (WDM) technology increase the amount of bandwidth available in fiber links by many orders of magnitude. However, this increase in link capacities is limited by the conventional electronic router’s capability. Optical burst switching (OBS) has been proposed as a promising and a short-term solution for switching technology to take advantage of increased capacity of optical links. The congestion in OBS control plane and the adaptive burst assembly algorithms are two important research topics that are among the most effective factors determining the performance of OBS networks. These two problems have been separately studied in the literature so far. It has been shown that contending bursts at a core optical switch in an OBS network may experience unfair loss rates based on their residual off- set times and burst lengths, that are called path length priority effect (PLPE) and burst length priority effect (BLPE), respectively. In this thesis, we propose a new adaptive timer-based burst assembly algorithm (ATBA) which uses loss rate measurements for determining the burstification delays of traffic streams in order to mitigate the undesired effects of PLPE and BLPE. ATBA distributes the burst generation rates of traffic streams at an ingress node such that total rate of generated bursts is constant in order to constrain the congestion in the control plane. Without ATBA, the fairness index drops to 76% when per hop processing delay (PHPD) is increasing. With ATBA, the fairness index drops only to 85% with increasing PHPD. It is also shown that the total goodput of the OBS network improves by 5% compared with the case without ATBA.Çırak, İsmailM.S

Cost-based burst dropping strategy in optical burst switching networks

Optical burst switching (OBS) is a new paradigm for future all-optical networks. Intentional burst dropping is one of techniques used to achieve desired quality of service. In this paper we note that some bursts are more likely to cause contention. We propose a cost function that can be used to predict the likelihood that a given burst will interfere with other traffic, then we explain how, by using this information a new burst dropping strategy can be designed. We compare our method with a random burst dropping technique and show that the cost-based approach offers a significant performance improvement

Performance issues in optical burst/packet switching

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-01524-3_8This chapter summarises the activities on optical packet switching (OPS) and optical burst switching (OBS) carried out by the COST 291 partners in the last 4 years. It consists of an introduction, five sections with contributions on five different specific topics, and a final section dedicated to the conclusions. Each section contains an introductive state-of-the-art description of the specific topic and at least one contribution on that topic. The conclusions give some points on the current situation of the OPS/OBS paradigms

Congestion window based adaptive burst assembly for TCP traffic in optical burst switching networks

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical references leaves 51-55.Burst assembly is one of the key factors affecting the TCP performance in Optical Burst Switching (OBS) networks. Timer based burst assembly algorithm generates bursts independent of the rate of TCP flows. When TCP congestion window is small, the fixed-delay burst assembler waits unnecessarily long, which increases the end-to-end delay and decreases the TCP goodput. On the other hand, when TCP congestion window becomes larger, the fixed-delay burst assembler may unnecessarily generate a large number of small-sized bursts, which increases the overhead and decreases the correlation gain, resulting in a reduction in the TCP goodput. Using simulations, we show that the usage of the congestion window (cwnd) size of TCP flows in the burst assembly algorithm consistently improves the TCP goodput (by up to 38.4%) compared with the fixed-delay timer based assembly even when the timer based assembler uses the optimum assembly period threshold value. One limitation of this proposed method is the assumption that the exact value of the congestion window is available at the burst assembler. We then extend the adaptive burstification algorithm such that the burst assembler uses estimated values of the congestion winpassive measurements at the ingress node. It is shown through simulations that even when estimated values are used, TCP goodput can achieve values close to the results obtained by using exact values of the congestion window. dow that are obtained viaÖzsaraç, SeçkinM.S

A novel ingress node design for video streaming over optical burst switching networks

This paper introduces a novel ingress node design which takes advantage of video data partitioning in order to deliver enhanced video streaming quality when using H.264/AVC codec over optical burst switching networks. Ns2 simulations show that the proposed scheme delivers improved video traffic quality without affecting other traffic, such as best effort traffic. Although the extra network load is comparatively small, the average gain in video PSNR was 5 dB over existing burst cloning schemes, with a maximum end-to-end delay of 17 ms, and jitter of less than 0.35 ms

QoS Considerations in OBS Switched Backbone Net-Works

Optical Burst Switching (OBS) was proposed as a hybrid switching technology solution to handle the multi-Terabit volumes of traffic anticipated to traverse Future Generation backbone Networks. With OBS, incoming data packets are assembled into super-sized packets called data bursts and then assigned an end to end light path. Key challenging areas with regards to OBS Networks implementation are data bursts assembling and scheduling at the network ingress and core nodes respectively as they are key to minimizing subsequent losses due to contention among themselves in the core nodes. These losses are significant contributories to serious degradation in renderable QoS. The paper overviews existing methods of enhancing it at both burst and transport levels. A distributed resources control architecture is proposed together with a proposed wavelength assignment algorithm

Enhancing the quality of service for real time traffic over optical burst switching (OBS) networks with ensuring the fairness for other traffics

Optical burst switching (OBS) networks have been attracting much consideration as a promising approach to build the next generation optical Internet. A solution for enhancing the Quality of Service (QoS) for high priority real time traffic over OBS with the fairness among the traffic types is absent in current OBS ’ QoS schemes. In this paper we present a novel Real Time Quality of Service with Fairness Ratio (RT-QoSFR) scheme that can adapt the burst assembly parameters according to the traffic QoS needs in order to enhance the real time traffic QoS requirements and to ensure the fairness for other traffic. The results show that RT-QoSFR scheme is able to fulfill the real time traffic requirements (end to end delay, and loss rate) ensuring the fairness for other traffics under various conditions such as the type of real time traffic and traffic load. RT-QoSFR can guarantee that the delay of the real time traffic packets does not exceed the maximum packets transfer delay value. Fur- thermore, it can reduce the real time traffic packets loss, at the same time guarantee the fair- ness for non real time traffic packets by determining the ratio of real time traffic inside the burst to be 50 – 60%, 30 – 40%, and 10 – 20% for high, normal, and low traffic loads respectively