OPS or OBS in the Core Network? -A Comparison of Optical Packet-and Optical Burst Switching (original) (raw)
Related papers
2003
Abstract Future network should be able to efficiently serve packet-based networks, such as the Internet. In this paper, based on results from COST 266, we explore characteristics of optical burst switching (OBS) and optical packet switching (OPS). Both node design and metropolitan area network (MAN) are discussed. A unique joint comparative performance evaluation of contention resolution in OBS and OPS are presented, as well as methods of quality of service (QoS) differentiation in OBS/OPS networks, and their performance.
Node architectures for optical packet and burst switching
2002
Optical Packet Switching (OPS) and Optical Burst Switching (OBS) are optical networking concepts based on fully exploiting fast dynamic allocation of (D)WDM channels. Compared to more static approaches focussing on providing end-toend optical channels, OPS and OBS aim at providing greater bandwidth efficiency, granularity and flexibility. In this paper we give an overview of the issues arising when designing an optical switch for either OPS or OBS, including packet formats, contention resolution techniques, and switching fabrics.
Analysis and design of optical burst switching networks
2005
Optical Burst Switching (OBS) is a hybrid technique between coarse grain optical circuit switching and fine grain optical packet switching. In OBS networks, user data is switched entirely in the optical domain, while control and management functions are performed in the electrical domain. This separation of the data plane and the control plane allows OBS networks to provide reasonably high levels of utilization while circumventing the need for optical buffering. In spite of OBS favorable features, several issues need to be addressed before OBS can be deployed in the Internet backbone. The objectives of this thesis are twofold: devise new methods for quality-of-service (QoS) provisioning in OBS networks, and develop new wavelength scheduling algorithms for enhancing the blocking probability in OBS networks. QoS provisioning is a major research problem in OBS networks. This is mainly because of the absence of the concept of "packet queues" in OBS networks. This thesis proposes two approaches for QoS provisioning in OBS networks. The first approach is a simple, yet effective scheme, called preemptive prioritized just enough time (PPJET). PP JET provides better service for high priority traffic by dropping reservations belonging to lower priority traffic using a new channel scheduling algorithm called preemptive latest Abstract in available unused channel with void filling (PLAUC-VF). Simulation results show that PPJET outperforms offset-based QoS schemes both in terms of dropping probability and end-to-end delay. As a second approach for solving the QoS problem in OBS networks, we present a detailed architecture for providing quantitative QoS guarantees with respect to endto-end delay, throughput, and packet loss probability in labeled OBS networks. The architecture describes a novel approach for applying fair scheduling algorithms in both the data plane of labeled OBS edge nodes and the control plane of core nodes without the need for optical buffering. In addition, we present analytical results for delay, throughput, and blocking probability in the proposed architecture. Simulation results demonstrate that the proposed architecture provides accurate and controllable service differentiation in labeled OBS networks. The absence of optical buffers in OBS nodes, coupled with the one way nature of OBS signaling protocols, drives the blocking probability to become the main performance measure in OBS networks. This give rise to the need for analytical models for calculating the blocking probability in OBS networks. In this thesis we present an approximate analytical model for calculating the blocking probability in OBS networks. The proposed analytical model takes into consideration the peculiar characteristics of OBS networks. To verify its accuracy, we compared the model results with results from a discrete-event simulation model. The proposed model results are in satisfactory agreement with simulation results.
New Contention Resolution Techniques for Optical Burst Switching
2005
Optical burst switching (OBS) is a technology positioned between wavelength routing and optical packet switching that does not require optical buffering or packet-level parsing, and it is more efficient than circuit switching when the sustained traffic volume does not consume a full wavelength. However, several critical issues still need to be solved such as contention resolution without optical buffering which is a key determinant of packet-loss with a significant impact on network performance. Deflection routing is an approach for resolving contention by routing a contending packet to an output port other than the intended output port. In OBS networks, when contention between two bursts cannot be resolved through deflection routing, one of the bursts will be dropped. However, this scheme doesn’t take advantage of all the available resources in resolving contentions. Due to this, the performance of existing deflection routing scheme is not satisfactory. In this thesis, we propose a...
Optical burst switching: a new area in optical networking research
IEEE Network, 2004
In this tutorial, we give an introduction to optical burst switching (OBS) and compare it with other existing optical switching paradigms. Basic burst assembly algorithms and their effect on assembled burst traffic characteristics are described first. Then a brief review of the early work on burst transmission is provided followed by the description of a prevailing protocol for OBS networks called Just-Enough-Time (JET). Algorithms used at an OBS core node for burst scheduling as well as contention resolution strategies are presented next. Tradeoffs between their performance and implementation complexities are discussed. Recent work on QoS support, IP/WDM multicast, TCP performance in OBS networks and Labelled OBS is also described, and several open issues are mentioned. Hereafter, we will use the terms channel and wavelength (or λ) interchangeably.
Optical burst switching (OBS)-a new paradigm for an optical Internet
Journal of high speed networks, 1999
To support bursty tra c on the Internet (and especially WWW) e ciently, optical burst switching (OBS) is proposed as a way to streamline both protocol and hardware in building the future generation Optical Internet. By leveraging the attractive properties of optical communications and at the same time, taking into account its limitations, OBS combines the best of optical circuitswitching and packet/cell switching. In this paper, the general concept of OBS protocols and in particular, those based on Just-Enough-Time (JET), is described, along with the applicability of OBS protocols to IP over WDM. Speci c issues such as the use of ber delay-lines (FDL) for accommodating processing delay and/or resolving con icts are also discussed. In addition, the performance of JET-based OBS protocols which use an o set time along with delayed reservation to achieve e cient utilization of both bandwidth and FDLs as well as to support priority-based routing is evaluated.
Contention Resolution Technique based on Packet Switching in Optical Burst Switched Networks
Optical Burst Switching (OBS) is a data switching technique for upcoming computer networks, since this technique can perform data switching and data processing operations with high speed and efficiency. Its main goal is to get rid of problems found in two main techniques, which are, Optical Circuit Switching (OCS) and Optical Packet Switching (OPS). Routing deflection methods route bursts to other output ports, in fact it is not intended to resolve contention. In OBS, when burst is not programmed on other output port through routing deflection then it is simply deleted. To route data to the receiver, the routing deflection does not resolve all aspects that resulted loss of data; therefore, the performance of schemes deflection existence is not acceptable by the systems and so it closes with deletion any plan to resolving contention, backtrack if deflection fails (BDF), that is given as a second opportunity to burst in order to face the failure through deflection, the blocked bursts will return to the previous station, to find suitable alternative available paths.
Study on the performance of slotted and non-slotted Optical Burst Switched networks
Current progress in optical communication is driven by the continuous growth of the number of Internet users and the explosion of bandwidth greedy applications. Three main optical switching paradigms are being investigated to cope with this evolution: Optical Circuit Switching (OCS), Optical Packet Switching (OPS) and Optical Burst Switching (OBS). Among these paradigms, OBS is seen as the most appropriate solution. However, OBS still suffers from high burst loss as a result of contention at the buffer-less core node. There exist two categories of OBS, slotted and non-slotted. In this paper, the performance of these two categories is evaluated. The evaluation is done through simulation and it consists of comparing Hierarchical Time Sliced OBS (HiTSOBS) a slotted OBS to the conventional non-slotted OBS. Simulation results show that, HiTSOBS architecture outperforms conventional OBS in terms of Burst Loss Ratio (BLR) and throughput. The high performance of HiTSOBS is attributed to the flexibility of its hierarchy and support of QoS.
On The Control Packet Structure of Optical Burst Switching Networks
Optical Burst Switching (OBS) is a prospective optical switching technology that can be deployed as the infrastructure of the future All-optical Internet. OBS is still at its definition phase. Hence, no definite OBS standard architecture has been established yet, including the control packet format. In this paper, a control packet structure is introduced. The structure provides constant transmission overhead and makes the control packet scalable to higher speeds. Without adjustments, the new control packet can be used with various OBS implementations. Furthermore, a simple analytical model is used to evaluate the performance of the OBS network, based on the new format of the control packet.