Optimal Burst Scheduling in Optical Burst Switched Networks (original) (raw)
Related papers
On ordered scheduling for optical burst switching
Computer Networks, 2005
Optical burst switching (OBS) is a promising optical networking paradigm for efficient transport of bursty IP traffic over wavelength division multiplexing (WDM) optical Internet networks. In OBS, the header of a burst is sent in advance of the data burst to reserve a wavelength channel at each optical switching node along the path. The nodes use a scheduling algorithm to assign wavelengths to incoming bursts. Our work is motivated from the observation that existing scheduling algorithms assign a wavelength to a burst when its header arrives at the node. Thus, information about other bursts whose headers arrive later is not available when the scheduling decision is made. This leads to suboptimal scheduling decisions and unnecessary burst dropping. The key idea in our proposed algorithm, Ordered Scheduling, is to defer making the scheduling decision until just before the burst arrival in order to have full knowledge about other bursts. The effectiveness of the proposed algorithm is studied through simulation and the computational complexity and signalling overhead are analysed.
Techniques for improved scheduling in optical burst switched networks
2009 International Symposium on Autonomous Decentralized Systems, 2009
Optical burst switching (OBS) has emerged as a viable switching alternative in backbone optical networks since it can support high data rates with an intermediate granularity compared to wavelength routing and optical packet switching. At the edges of an OBS cloud, packets are assembled to form bursts which enter the network core and are switched on the fly using bandwidth previously reserved by their control packets at each node. A key problem in OBS networks is the assignment of wavelengths to incoming bursts, i.e. the scheduling of bursts. This paper proposes two new techniques which are shown to improve burst scheduling algorithms by lowering their complexity. The first proposed technique is based on a triangular estimator that defines a "drop zone"; bursts that fall into this area are considered to have a very low probability of finding a suitable wavelength and as such, no effort is made to schedule them. According to the second approach, the drop zone is defined dynamically based on the burst drop history. Simulation results show that both approaches yield burst drop rates marginally higher or identical to the LAUC-VF scheduling algorithm while reducing the number of channel or void checks and thus the algorithm complexity and execution time.
Efficient resource reservation for optical burst switching networks
2009 IEEE Global Telecommunications Conference, GLOBECOM 2009
Optical burst switching (OBS) is one promising method for data transfer in photonic networks based on a WDM (Wavelength Division Multiplexing) technology. In the OBS scheme, the wavelength is exclusively reserved along the source and destination nodes, when the burst data is generated at the source. Then, efficient data transfer is expected. However, its performance is heavily dependent on the number of links that the lightpath goes through. TCP-based applications account for a majority of data traffic in the Internet; thus understanding and improving the performance of TCP over OBS networks is critical. In this paper, we present a new parallel wavelength reservation method for optical burst switching (OBS) networks based on adapting the set of potential wavelengths with the number of hops in the path. The uniqueness of this work when compared to existing works is that buffering resources, which consist of Optical Delay Lines (ODLs), are considered in the reservation mechanism. The consequence of this is that the time made by the segments in the various buffers across the selected path is taken into consideration. Various simulation experiments have been conducted to evaluate the performance of the scheme. It is found that our approach has better performance than previous related works reported in the literature. http://ieeexplore.ieee.org/xpls/abs\_all.jsp?arnumber=5425688
A cost-effective approach to optical packet/burst scheduling
2007
Abstract Optical burst and packet switching are being considered as the most promising paradigms to increase bandwidth efficiency in IP over DWDM networks. In both cases, due to statistical multiplexing, a scheduling policy is needed to solve contentions at the node level caused by more than one burst/packet directed to the same output channel. The scheduling may be performed in the wavelength, time and space domains, turning this problem into a choice of the best available resource in the different domains.
Batch Scheduling Algorithms for Optical Burst Switching Networks
2005
Previously proposed wavelength scheduling algorithms in optical burst switching networks process each reservation request individually and in a greedy manner. In this paper we propose a new family of wavelength scheduling algorithms that process a batch of reservation requests together instead of processing them one by one. When a control burst with a reservation request arrives to a free batch scheduler, the scheduler waits for a small amount of time, called the acceptance delay, before deciding to accept or reject the reservation request. After the acceptance delay has passed, the scheduler processes all the reservation requests that have arrived during the acceptance delay, then it accepts the requests that will maximize the utilization of the wavelength channels. We describe an optimal batch scheduler that serves as an upper bound on the performance of batch scheduling algorithms. Furthermore, we introduce two heuristic batch scheduling algorithms. The performance of the proposed algorithms is evaluated using a discrete-event simulation model. Simulation results suggest that batch schedulers could decrease the blocking probability by 25% compared to the best previously known wavelength scheduling algorithm.
Segmentation-based On-Demand Burst Rescheduling Algorithm for Optical Burst Switched Networks
Optical Burst Switching (OBS) is a type of switching technology capable of harnessing the Wavelength Division Multiplexing (WDM) capability by aggregating different client packets into larger packets known as bursts. OBS is a promising candidate for near-future all-optical networks. However, large burst loss at the core node due to contention is a key issue and it is caused by the bufferless nature of OBS architecture. This paper focuses on scheduling as a means to reduce contention and improve the overall network performance in terms of loss and throughput. Two important design criteria for scheduling algorithms are speed and link utilization. These criteria are not supported in current scheduling algorithms due to the trade-off between control packet processing speed and efficient utilization of the bandwidth resource. In this paper, a Segmentation-based On-Demand Burst Rescheduling Algorithm (SODBRA) is proposed and evaluated. In SODBRA, the aforementioned trade-off is balanced b...
Iet Communications, 2009
A strategy for minimising the probability of contention in optical burst-switching (OBS) networks, by combining traffic engineering in the wavelength domain with delayed burst scheduling at the ingress nodes, has been proposed. The implementation of this strategy only requires an increase on the processing and electronic buffering capacities of the ingress nodes, while avoiding the use of complex and expensive optical buffers at the core nodes. The performance evaluation study has shown that the proposed strategy outperforms the burst-scheduling strategies described in the literature by several orders of magnitude, in terms of burst-blocking probability. Moreover, the performance improvements have been shown to depend on the average offered traffic load, number of wavelengths per link and maximum delay allowed at the ingress nodes.
Optical burst switching is a promising solution for terabit transmission of IP data bursts over WDM networks. Optical Burst Switching (OBS) is a promising paradigm for the next-generation Internet. In this paper, we propose a random algorithm, first-fit wavelength algorithm and wavelength reservation algorithm. The blocking probability of the Optical Burst Switch will be analyzed depending upon the number of channels, loads and the number of links. The number of wavelengths on all the links will be kept constant. The blocking probability of the proposed scheme is significantly reduced as compare with general OBS.
Proceedings of the International Conference on Communication and Signal Processing 2016 (ICCASP 2016), 2017
Optical burst switching (OBS) is envisioned to be one of the most promising technology to support all-optical switching in the optical Internet. OBS is finding potential in bandwidth hungry applications like, grid computing, video conferencing, video telephony and video on demand. In this critical high speed Internet based applications, where bursts losses should be minimized. In OBS based networks, there exists the possibility that bursts may contend with one another at intermediate nodes. Typically, contention resolution in IP networks is implemented by storing excess packets in electronic buffer (RAM). However, electronic like buffer is unavailable and optical buffer is constructed from fiber delay lines (FDL). An FDL is simply the length of fiber and offer a deterministic delay. We present simulation results which show the effect of the use of FDLs of various delays to reduce bursts losses. The simulation results show that such limited optical buffers can significantly reduces burst losses in the network.
Performance analysis of an optical burst switching (OBS) network
2008 International Conference on Electrical and Computer Engineering, 2008
The development of wavelength division multiplexing opens a new horizon in optical networks and promises to be one of the best solutions for the high demand of the bandwidth. However, with this technology, many problems arise, especially those related to the architecture to be used in optical networks to take advantage of the huge potential of this technique. Many approaches and architectures have been proposed in literatures to carry information in optical domain. Among them, optical burst switching (OBS) and wavelength routed network seems to be the most successful. We propose a new novel architecture that uses both methods in order to overcome the limitations imposed by each approach. The proposed architecture deploys bursty traffic in a hybrid fashion where implicitly predicted and explicitly pre-booked traffic are dynamically allocated reserved end-to-end paths, inheriting the spirit of conventional wavelength routing; whilst, the non-predicted traffic is transmitted via classical OBS reservation mechanism(s) with the best efforts support. The complete network structure alongwith load-balancing prior reservation strategy is presented. Simulation results reveal the performance of the proposed work by examining the blocking probability and delay characteristics. The encouraging results provide stimulation for further work on optimal traffic placement, QoS provisioning, and various apriori resource reservation strategies.