Alternative Multiple Spanning Tree Protocol (AMSTP) for Optical Ethernet Backbones

The availability and affordable cost of Gigabit and 10 Gigabit Ethernet switches has impacted the deployment of metropolitan area networks (MAN) and campus networks. This paper presents a new protocol, the alternative multiple spanning tree protocol (AMSTP), that uses multiple source based spanning trees for backbones using Ethernet switches. It provides minimum paths and more efficient usage of optical backbone infrastructure than currently proposed protocols such as resilient packet ring and rapid spanning tree. The protocol exhibits features similar to MAC routing protocols like Link State Over MAC (LSOM) such as optimum path and effective infrastructure usage, without requiring MAC routing due to the use of the spanning tree protocol paradigm. AMSTP is not restricted to specific topologies such as ring or tree, but performs efficiently in arbitrary topologies. Among the application areas are optical backbones of campus and MANs.Publicad

Benchmarking and viability assessment of optical packet switching for metro networks

Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained

Novel algorithms for fair bandwidth sharing on counter rotating rings

Rings are often preferred technology for networks as ring networks can virtually create fully connected mesh networks efficiently and they are also easy to manage. However, providing fair service to all the stations on the ring is not always easy to achieve. In order to capitalize on the advantages of ring networks, new buffer insertion techniques, such as Spatial Reuse Protocol (SRP), were introduced in early 2000s. As a result, a new standard known as IEEE 802.17 Resilient Packet Ring was defined in 2004 by the IEEE Resilient Packet Ring (RPR) Working Group. Since then two addenda have been introduced; namely, IEEE 802.17a and IEEE 802.17b in 2006 and 2010, respectively. During this standardization process, weighted fairness and queue management schemes were proposed to be used in the standard. As shown in this dissertation, these schemes can be applied to solve the fairness issues noted widely in the research community as radical changes are not practical to introduce within the context of a standard. In this dissertation, the weighted fairness aspects of IEEE 802.17 RPR (in the aggressive mode of operation) are studied; various properties are demonstrated and observed via network simulations, and additional improvements are suggested. These aspects have not been well studied until now, and can be used to alleviate some of the issues observed in the fairness algorithm under some scenarios. Also, this dissertation focuses on the RPR Medium Access Control (MAC) Client implementation of the IEEE 802.17 RPR MAC in the aggressive mode of operation and introduces a new active queue management scheme for ring networks that achieves higher overall utilization of the ring bandwidth with simpler and less expensive implementation than the generic implementation provided in the standard. The two schemes introduced in this dissertation provide performance comparable to the per destination queuing implementation, which yields the best achievable performance at the expense of the cost of implementation. In addition, till now the requirements for sizing secondary transit queue of IEEE 802.17 RPR stations (in the aggressive mode of operation) have not been properly investigated. The analysis and suggested improvements presented in this dissertation are then supported by performance evaluation results and theoretical calculations. Last, but not least, the impact of using different capacity links on the same ring has not been investigated before from the ring utilization and fairness points of view. This dissertation also investigates utilizing different capacity links in RPR and proposes a mechanism to support the same

Resilient Packet Ring: una tecnologia per il futuro delle Reti Metropolitane

Il rapido aumento del volume di traffico nelle reti metropolitane sta sfidando i limiti di capacit`a delle esistenti infrastrutture di trasporto basate su tecnologie circuit-oriented quali SONET e ATM. Le inefficienze associate al trasporto di crescenti quantita' di traffico dati su reti circuit-switched ottimizzate per la voce rende difficile fornire nuovi servizi ed incrementa il costo dell'aggiunta di capacita' oltre i limiti della maggior parte dei carrier. In questo articolo viene esaminata la tecnologia di trasporto packetbased RPR (Resilient Packet Ring), una solida alternativa per adattare le reti metropolitane alle crescenti richieste.Metropolitan Area Network, Resilient Packet Ring.

Measurement Based Reconfigurations in Optical Ring Metro Networks

Single-hop wavelength division multiplexing (WDM) optical ring networks operating in packet mode are one of themost promising architectures for the design of innovative metropolitan network (metro) architectures. They permit a cost-effective design, with a good combination of optical and electronic technologies, while supporting features like restoration and reconfiguration that are essential in any metro scenario. In this article, we address the tunability requirements that lead to an effective resource usage and permit reconfiguration in optical WDM metros.We introduce reconfiguration algorithms that, on the basis of traffic measurements, adapt the network configuration to traffic demands to optimize performance. Using a specific network architecture as a reference case, the paper aims at the broader goal of showing which are the advantages fostered by innovative network designs exploiting the features of optical technologies

Recovery fairness and congestion control mechanisms in RPR networks

The paper describes fundamental features of RPR (Resilient Packet Ring - IEEE 802.17 standard). It focuses on proposals how to improve fairness mechanism and to increase network efficiency in state of congestion. Recovery mechanisms are also discussed, with presented analytical and simulation results. The goals of paper are threefold. At first, we show RPR main features and describe its current status. Secondly, we present main recovery and resilience features of RPR and propose solutions for improving both fairness and congestion control. Finally, a new concept, the enhanced hold-off timer (EHOT) is introduced improving recovery actions in multilayer networks. Some simulation results are presented in order to illustrate advantages of proposed solution.Postprint (published version

Congestion control in resilient packet ring networks

The Resilient Packet Ring (RPR) is a new metro technology; RPR shares SONET\u27s ability in providing fast recovery from link and node failures as well as inherits the cost and simplicity of Ethernet. RPR, like SONET/SDH, is a ring based architecture consisting of two optical rotating rings (uni-directional). In RPR, packets are removed from the ring at the destination so that different segments of the ring can be used at the same time for different flows; as a result, the spatial reuse feature is achieved. Enabling the spatial reuse feature introduces the challenge of guaranteeing fairness among the nodes sharing the same link. The RPR fairness algorithm is comparatively simple, but it poses some critical limitations. One of the major problems is that the amount of bandwidth allocated by the algorithm oscillates severely under unbalanced traffic scenarios. These oscillations are a barrier to achieving spatial reuse and high bandwidth utilization. Moreover, the current RPR standard uses a single FIFO for each class at the ingress point, thus resulting in the head of line blocking problem. On the other hand, RPR uses the shortest path to route the traffic in the dual ring which is inefficient and unfair. In this dissertation, the performance of the existing fairness algorithms and their limitations was investigated. Two bandwidth allocation algorithms were proposed to address the fairness issue. Both algorithms were demonstrated analytically and through simulations were able to achieve fairness and maximize the ring utilization. The Distributed Bandwidth Allocation (DBA) and the Adaptive Bandwidth Allocation (ABA) do not need to maintain information about each node. Instead, they use the local information which makes them scalable for a ring with any number of nodes. The Simple Scheduling Algorithm (SSA) was proposed to avoid the head of line blocking and to maximize the ring utilization at a very low complexity. The SSA algorithm was shown analytically and through simulations to be optimal where the flows achieve their max-mm fair rates at a very low computational complexity. Also, the weighted routing algorithm was proposed to maximize the ring utilization by enabling the RPR nodes to transmit in both rings in a weighted manner. The routing algorithm was demonstrated analytically and through simulations was able to maximize the ring utilization

Benchmarking and viability assessment of optical packet switching for metro networks

Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained

Future development trends of optical transport network infrastructure: an infrastructual framework for metropolitan-based optical transport networks - a field test of a Chinese ISP and a case study of a Chinese Electric Power Company

Optical Transport Networks (OTNs) play a foundational role in current and future telecommunication infrastructure. However, the development and implementation of OTNs have been restrained since the bursting of the dot-com bubble. Many service providers and large companies are confused in the development directions of future OTN infrastructure, as there are several standards organisations with differing positions. On the other hand, there is a lack of large scale testing, as well as practical implementation cases due to the emerging nature of the OTN. Therefore, this thesis develops a framework demonstrating a landscape of current and future development steps of OTN infrastructure from both theoretical and commercial standpoints. The key concept of the framework is the integration of the IP-oriented data transmission layer and the WDM-based optical transport layer. Traditional telecommunication infrastructure focuses on long-haul, point-to-point optical transmission with ultra broadband carrier capacity. Nevertheless, the next generation OTN systems will emphasis the delivery of IP-oriented multifunctional data services, instead of legacy simplex TDM-based services across a metropolitan span with sufficient reliability and efficiency. Thus, this thesis gives a systematic validation of the proposed framework from two angles. Firstly, it provides in-depth research on the evolution of protection technologies in metro core optical networks, along with a MPLS-based network fast recovery field test to validate the framework from the network reliability aspect. The field test was conducted using a large Chinese ISP test bed and demonstrated the practical performance of the advanced OTN protection technology from the perspective of a service provider. Secondly, this research presents a comprehensive case study based on a large commercial metro OTN upgrade project of Shanghai Municipal Electric Power Company (SMEPC). The outcome of the case study is an evolutional roadmap, which illustrates the infrastructural development trends of this ongoing project. The roadmap can be considered as another evaluation of the framework in terms of network efficiency from an industrial-based dimension. The outcome of this research is to clarify future development trends in OTN infrastructure for the purpose of informing the design and implementation of commercial OTN applications