Extended bimodal burst switching architecture

Optical burst switching (OBS) is a switching technology that can efficiently operate in the optical core network using WDM technology and can also develop the future optical internet. The OBS switching technology presents a trade-off between the two switching technologies: optical circuit switching (OCS) and optical packet switching (OPS). This switching approach increases resource utilization compared with OCS technology and avoids the technological barriers of OPS networks. In OBS networks, many packets are assembled into one data burst at the edge node and a burst header packet (BHP) is sent before the burst transmission by an offset time in order to reserve the required resources in core nodes. This can cause security issues in the network and more specifically denial of service attacks that can occur if a source node is compromised. In this paper, we study a specific denial of service attack which we refer to as "BHP flooding attack", which prevents legitimate traffics from reserving the required resources at intermediate core nodes. We also propose the design of a reconfigurable BHP flooding countermeasure module that allows to counter against this type of attacks in an OBS network.

In this paper the end-to-end TCP performance of a hybrid network composed of multiple Ethernet Passive Optical Networks (EPONs) in the access segment connected to the same edge node of a core network is evaluated. Three possible core network paradigms are considered: Optical Circuit Switching (OCS), Optical Burst Switching (OBS) and Optical Packet Switching (OPS). TCP performance is evaluated through simulations with ns-2. The hybrid network scalability is assessed by varying the number of EPONs connected to the same edge node and the number of Optical Network Units (ONUs) per EPON. Interoperability issues between access and core are investigated and the impact of the most important network parameters is highlighted. The three transfer modes considered for the core network are properly compared under different input conditions, discussing the related trade-offs that may lead to the most suitable choice based on the specific application scenario. Finally, some design issues are investigated with reference to emerging Long-Range EPON (LR-EPON) solutions.

On burst assembly in optical burst switching networks—A performance evaluation of just-enough-time

Hybrid optical switching networks make full use of the advantages of Optical Circuit Switching (OCS) and Optical Burst Switching (OBS). In parallel hybrid optical switching networks, edge nodes choose a switching mode for traffic and no longer change. The inflexible decision making of the traffic transfer mode leads to low resource utilization when the arrival rate of the OCS traffic is lower than the capacity of the light path. In this paper, a new transmission scheme is proposed to improve resource utilization for hybrid optical switching networks. When the traffic arrival rate of the light path is lower than the transmission rate of the light path, the OCS traffic flow is reshaped at the edge nodes to generate a series of voids. Then, several message packets are sent along the light path to inform the core nodes of the voids of the light paths that represent the unused bandwidth resources. To improve the resource utilization, the voids can be filled with data bursts by core nodes. The simulation results show that the new scheme can effectively reduce the burst loss rate and improve the link utilization of the hybrid optical switching network on the premise of a providing service quality guarantee for OCS traffic.

Parallel Optical Burst Switching (POBS) is a variant of Optical Burst Switching (OBS) which is proposed as a new optical switching strategy for Ultra-Dense Wavelength Division Multiplexing (U-DWDM) to support the enormous bandwidth demand of the next generation Internet. As opposed to OBS, POBS transmits bursts in two dimensions: the wavelength dimension and the time dimension. POBS network uses an one-way resource reservation mechanism to set up the resources for each data burst transmission. The use of this mechanism may cause bursts to contend for the same resources at the same time at core (intermediate) nodes of the network. Therefore, the performance of POBS networks depends on the contention resolution policies to reach acceptable levels for bandwidth usage. These policies may increase both the cost and complexities of the core nodes in POBS networks. Most literatures on OBS networks apply contention resolution at the core nodes based on reactive strategies that are activated after contention takes place in core nodes. This study proposes the use of a proactive contention resolution technique at ingress nodes of POBS network as well as reactive contention resolution technique at core nodes for reducing the probability of burst drop in the network in order to increase the performance of the network. The simulation results show that the use of POBS network with the proposed Reactive Odd/Even Node ID Wavelength Assignment Technique (POBS-ROENIDWAT) shows a better performance in terms of reduced data loss rate and increased throughput compared to the performances of both POBS network with Sequential Wavelength Assignment Technique (POBS-SWAT) and OBS network with Burst Segmentation (OBS-BS).

Optical Circuit Switching (OCS) provides a good support for the services requiring high bandwidth and Quality of Service (QoS). When the character of network traffic changes from voice-oriented to data-oriented, OCS must cooperate with new switching mechanisms such as Optical Burst Switching (OBS) to improve performance. So a Hybrid Optical Switching (HOS) system is proposed. In HOS, different traffics are classified and both OBS and OCS can be processed. At the same time, delay buffer mechanisms, which are Fiber Delay Line (FDL) and electronic buffering, are introduced in HOS to solve the contention of OBS bursts. And a wavelengths classification mechanism, which assigns some wavelengths dedicated to OCS traffics, is provided to guarantee the QoS of OCS. To analyze the performance in theory, models based on Markovian theory and iterative method are provided. The results got by theory are accurate compared with simulations. The use of delay buffer can decrease the blocking probability of OBS and increase resource utilization. Wavelength classification mechanism benefits to improve OCS's performance.

Hybrid optical networks (HONs) are the combination of different switching mechanisms such as Optical Circuit Switching (OCS), Optical Burst Switching (OBS) and Optical Packet Switching (OPS). The basic idea behind HONs is to integrate the advantages of different switching mechanisms. HONs are classified into three classes as: (1) parallel hybrid optical networks, (2) integrated hybrid optical networks, (3) client-server hybrid optical networks. In this article, we describe these classes in detail and a new integrated hybrid optical network called EISM (Efficient Integration of Switching Mechanisms in all-optical networks) is introduced. The proposed EISM method could perform optimally while considering some implementation criteria; such criteria include network bandwidth utilization, implementation complexity and also the domain of network performance by combining four switching mechanisms-OCS, long-OBS, short-OBS and OPS.

Hybrid optical switching (HOS) is a switching paradigm that aims to combine optical circuit switching, optical burst switching, and optical packet switching on the same network. This paper proposes a novel integrated control plane for an HOS core node. The control plane makes use of a unified control packet able to carry the control information for all the different data formats and employs an appropriate scheduling algorithm for each incoming data type. Three possible node architectures are presented and an analytical model is introduced to analyze their power consumption. Also, the concept of increase in power efficiency is introduced to compare the considered architectures. The performance and power consumption analysis of the node have been carried out through the use of a simulation model developed specifically for the scope. The obtained results show the effectiveness of HOS networks.

We develop an integrated optical packet and circuit switching node in which signaling via optical packet switching is implemented. We demonstrate 80 (8λ × 10) Gbit/s optical packet switching with <;1E-4 packet-loss-rate, 8-lightpaths establishment, and dynamic wavelength-resources control.

DWDM multi-mode switching network provides a unified approach to DWDM-based communications by allowing electronic packet switching (EPS), optical burst switching (OBS) and optical circuit switching (OCS) to be carried in the same network, and on the same router platform. In this paper, we present a sub-millisecond dynamic optical path setup scheme for the multi-mode switching router. More specifically, we devised a reconfigurable asymmetric optical burst switching (RA-OBS) scheduling scheme which integrates burst scheduling in the OBS mode, connection setup/teardown in the OCS mode, and channel reconfiguration in the EPS mode in a seamless fashion. The proposed scheme allows wavelengths to be dynamically shared among three different switching modes in real-time. The performance of the proposed integrated scheduler has been verified using OBS-ns2 simulator as well as in a hardware testbed. In particular, we have implemented the proposed integrated multi-mode scheduler in FPGA hardware in an optical switching testbed, and have demonstrated application triggered real-time sub-millisecond optical path setup. Another key contribution is that the proposed approach brings out the practical value of optical burst switching, which has stayed mostly in the theoretical regime in the past decade. We show that a truly dynamic optical network can be built with off-the-shelf optical components.

Optical burst switching (OBS) is a new optical switching paradigm where traffic can be switched and groomed at a lower level compared to optical switched circuit (OCS). While OCS is useful in carrying highly aggregated long-lived streams that require absolute quality of service (QoS) guarantees, OBS has a role in efficiently carrying bursty best-effort traffic. In this paper, we investigate further the comparative goodput and bandwidth efficiency of OBS and OCS using, on one hand, an adaptive deflection OBS routing that aims at minimizing the burst loss rate and, on the other hand, a routing and wavelength OCS strategy using the best possible routing paths for minimizing the blocking rate.

The service evolution and the rapid increase in traffic levels fuel the interest toward switching paradigms enabling the fast allocation of Wavelength Division Multiplexing WDM channels in an on demand fashion with fine granularities (microsecond scales). For this reason, in the last years, different optical switching paradigms have been proposed (Sabella et al., 2000): optical-packet switching (OPS), optical-burst switching (OBS), wavelength-routed OBS, etc. Among the various all-optical switching paradigms, OPS attracts increasing attention. Owing to the high switching rate, Semiconductor Optical Amplifier (SOA) is a key technology to realize Optical Packet Switches. We propose some Optical Packet Switch (OPS) architectures and illustrate their realization in SOA technology. The effectiveness of the technology in reducing the power consumption is also analyzed. The chapter is organized in three sections. The main blocks (Switching Fabric, Wavelength Conversion stage, Synchronization stage) of an OPS are illustrated in Section 2 where we also show some examples of realizing wavelength converters and synchronizers in SOA technology. Section 3 introduces SOA-based single-stage and multi-stage switching fabrics. Finally the SOA-based OPS power consumption is investigated in Section 4.

Modeling and performance analysis of a data center network (DCN) combining optical packet switching (OPS) and agile optical circuit switching (OCS) in a unified platform are presented. Hybrid optoelectronic packet routers which combine optical switching fabric and electronic buffers are used, supporting 100 Gbit/s (25 Gbit/s × 4 wavelengths) optical packets. OCS transmission is implemented by a novel “express path,” (ExP) an instant wavelength path on demand, which enables certain flows following the ExP with no packet contention, whereas ordinary OPS packets are switched with a deflection routing algorithm and buffering for contention resolution. This architecture can support OCS for large and reliability-sensitive data transferring and OPS for latency-sensitive applications. The performance of the network is investigated via numerical simulations of top-of-rack switch (ToR)-to-ToR traffic in an N-dimensional (up to 4096 node) torus topology. We have made the following observations: 1) torus topology results in high throughput and can be scaled out by increasing the dimension; 2) contention resolution between OPS and agile OCS is needed and our proposed strategies enhance the overall performance; and 3) in a lightly to moderately loaded case of OPS traffic, more than 100 ExPs can be supported simultaneously with acceptable affect on OPS.

The paper presents the Multi-Service Photonic Network (MSPN) architecture, implementing the idea of optical circuit, burst and packet switching coexistence. We focus on the architecture using a layered perspective, and describe each layer functionality and technical implementation. Generic node structure gives a systematic description of MSPN functionalities through switching elements and transport interfaces. The implementation of new switching paradigms is particularly addressed by the discussion of the ways of transporting possibilities of optical packet/burst switching services over optical circuit switching services optical packet/burst. The MSPN support of different topological paradigms is of essential importance for the next generation optical transmission network deployment.

In this work we propose an optical burst switching retransmission scheme without any loss of bursts for star topology networks that exploits the entire network capacity. The basic idea is to allow the core node to resolve contentions by itself; balancing the intelligence of the network between edge and core nodes, losing neither the advantages of optical burst switching nor the simplicity of the core switch architecture. To achieve this objective, two retransmissions schemes are defined. The former confines the average number of retransmissions per burst below 2. The later exploits the whole network capacity.