Round-robin burst assembly and constant transmission scheduling for optical burst switching networks

Abstract — In this paper, we propose a round-robin burst assembly and constant burst transmission for optical burst switching (OBS) network. In the proposed method, ingress edge node has multiple buffers where IP packets are stored depending on their egress edge nodes, and bursts are assembled at the buffers in round-robin manner. Moreover, bursts are transmitted at fixed intervals with scheduler. To evaluate the performance of the proposed method, we construct a loss model with deterministic and Poisson arrivals, and explicitly derive burst loss probability, burst throughput, and data throughput. In numerical examples, we show the effectiveness of our analysis and compare the performance of the proposed method with Erlang loss system. I

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

Cost functions in optical burst-switched networks

Optical Burst Switching (OBS) is a new paradigm for an all-optical Internet. It combines the best features of Optical Circuit Switching (OCS) and Optical Packet Switching (OPS) while avoidmg the mam problems associated with those networks .Namely, it offers good granularity, but its hardware requirements are lower than those of OPS. In a backbone network, low loss ratio is of particular importance. Also, to meet varying user requirements, it should support multiple classes of service. In Optical Burst-Switched networks both these goals are closely related to the way bursts are arranged in channels. Unlike the case of circuit switching, scheduling decisions affect the loss probability of future burst This thesis proposes the idea of a cost function. The cost function is used to judge the quality of a burst arrangement and estimate the probability that this burst will interfere with future bursts. Two applications of the cost functio n are proposed. A scheduling algorithm uses the value of the cost function to optimize the alignment of the new burst with other bursts in a channel, thus minimising the loss ratio. A cost-based burst droppmg algorithm, that can be used as a part of a Quality of Service scheme, drops only those bursts, for which the cost function value indicates that are most likely to cause a contention. Simulation results, performed using a custom-made OBS extension to the ns-2 simulator, show that the cost-based algorithms improve network performanc

Flow control and service differentiation in optical burst switching networks

Cataloged from PDF version of article.Optical Burst Switching (OBS) is being considered as a candidate architecture for the next generation optical Internet. The central idea behind OBS is the assembly of client packets into longer bursts at the edge of an OBS domain and the promise of optical technologies to enable switch reconfiguration at the burst level therefore providing a near-term optical networking solution with finer switching granularity in the optical domain. In conventional OBS, bursts are injected to the network immediately after their assembly irrespective of the loading on the links, which in turn leads to uncontrolled burst losses and deteriorating performance for end users. Another key concern related to OBS is the difficulty of supporting QoS (Quality of Service) in the optical domain whereas support of differentiated services via per-class queueing is very common in current electronically switched networks. In this thesis, we propose a new control plane protocol, called Differentiated ABR (D-ABR), for flow control (i.e., burst shaping) and service differentiation in optical burst switching networks. Using D-ABR, we show with the aid of simulations that the optical network can be designed to work at any desired burst blocking probability by the flow control service of the proposed architecture. The proposed architecture requires certain modifications to the existing control plane mechanisms as well as incorporation of advanced scheduling mechanisms at the ingress nodes; however we do not make any specific assumptions on the data plane of the optical nodes. With this protocol, it is possible to almost perfectly isolate high priority and low priority traffic throughout the optical network as in the strict priority-based service differentiation in electronically switched networks. Moreover, the proposed architecture moves the congestion away from the OBS domain to the edges of the network where it is possible to employ advanced queueing and buffer management mechanisms. We also conjecture that such a controlled OBS architecture may reduce the number of costly Wavelength Converters (WC) and Fiber Delay Lines (FDL) that are used for contention resolution inside an OBS domain.Boyraz, HakanM.S

Network level performance of differentiated services (diffserv) networks

The Differentiated Services (DiffServ) architecture is a promising means of providing Quality of Service (QoS) in Internet. In DiffServ networks, three service classes, or Per-hop Behaviors (PHBs), have been defined: Expedited Forwarding (EF), Assured Forwarding (AF) and Best Effort (BE). In this dissertation, the performance of DiffServ networks at the network level, such as end-to-end QoS, network stability, and fairness of bandwidth allocation over the entire network have been extensively investigated. It has been shown in literature that the end-to-end delay of EF traffic can go to infinity even in an over-provisioned network. In this dissertation, a simple scalable aggregate scheduling scheme, called Youngest Serve First (YSF) algorithm is proposed. YSF is not only able to guarantee finite end-to-end delay, but also to keep a low scheduling complexity. With respect to the Best Effort traffic, Random Exponential Marking (REM), an existing AQM scheme is studied under a new continuous time model, and its local stable condition is presented. Next, a novel virtual queue and rate based AQM scheme (VQR) is proposed, and its local stability condition has been presented. Then, a new AQM framework, Edge-based AQM (EAQM) is proposed. EAQM is easier to implement, and it achieves similar or better performance than traditional AQM schemes. With respect to the Assured Forwarding, a network-assist packet marking (NPM) scheme has been proposed. It has been demonstrated that NPM can fairly distribute bandwidth among AF aggregates based on their Committed Information Rates (CIRs) in both single and multiple bottleneck link networks

SARDANA: an all-optical access-metro WDM/TDM-PON

A new optical access network, named “Scalable Advanced Ring-based passive Dense Access Network Architecture” (SARDANA), is presented. It transparently integrates WDM metro and TDM PON access technologies, implementing ring protection, 100 km reach and up to 1024 users served at 10 Gb/s, with passive highly-shared infrastructure. The introduced innovations are hybrid ring/tree WDM/TDM Passive Optical Network (PON) architecture; a resilient remote node (RN), which is distantly pumped from the Optical Line Terminal (OLT); and a reflective ONU (Optical Network Unit); as well as an enhanced Medium Access Control (MAC) protocol.Postprint (published version

Traffic and performance evaluation for optical networks. An Investigation into Modelling and Characterisation of Traffic Flows and Performance Analysis and Engineering for Optical Network Architectures.

The convergence of multiservice heterogeneous networks and ever increasing Internet applications, like peer to peer networking and the increased number of users and services, demand a more efficient bandwidth allocation in optical networks. In this context, new architectures and protocols are needed in conjuction with cost effective quantitative methodologies in order to provide an insight into the performance aspects of the next and future generation Internets. This thesis reports an investigation, based on efficient simulation methodologies, in order to assess existing high performance algorithms and to propose new ones. The analysis of the traffic characteristics of an OC-192 link (9953.28 Mbps) is initially conducted, a requirement due to the discovery of self-similar long-range dependent properties in network traffic, and the suitability of the GE distribution for modelling interarrival times of bursty traffic in short time scales is presented. Consequently, using a heuristic approach, the self-similar properties of the GE/G/¿ are being presented, providing a method to generate self-similar traffic that takes into consideration burstiness in small time scales. A description of the state of the art in optical networking providing a deeper insight into the current technologies, protocols and architectures in the field, which creates the motivation for more research into the promising switching technique of ¿Optical Burst Switching¿ (OBS). An investigation into the performance impact of various burst assembly strategies on an OBS edge node¿s mean buffer length is conducted. Realistic traffic characteristics are considered based on the analysis of the OC-192 backbone traffic traces. In addition the effect of burstiness in the small time scales on mean assembly time and burst size distribution is investigated. A new Dynamic OBS Offset Allocation Protocol is devised and favourable comparisons are carried out between the proposed OBS protocol and the Just Enough Time (JET) protocol, in terms of mean queue length, blocking and throughput. Finally the research focuses on simulation methodologies employed throughout the thesis using the Graphics Processing Unit (GPU) on a commercial NVidia GeForce 8800 GTX, which was initially designed for gaming computers. Parallel generators of Optical Bursts are implemented and simulated in ¿Compute Unified Device Architecture¿ (CUDA) and compared with simulations run on general-purpose CPU proving the GPU to be a cost-effective platform which can significantly speed-up calculations in order to make simulations of more complex and demanding networks easier to develop