Norvald Stol

A packet-switched hybrid optical network with service guarantees

We show that our proposed optical packet switched (OPS) hybrid network model supports both high throughput efficiency and guaranteed service transport (GST) with no packet loss and constant delay. The network comprises a wavelength routed optical network (WRON) enabling GST, and a statistically multiplexed (SM) network enabling high throughput. In the WRON, packets follow a fixed wavelength path and forwarding is based on the packets wavelength, while in the SM network, packets are switched according to header information. High reliability of GST packet forwarding is possible, because the forwarding does not depend on the operation of the packet switch. A novel node design supporting three Quality of Service (QoS) classes is proposed and described in detail. It facilitates full sharing of the link bandwidth by segregating GST packets and SM packets using polarization time division multiplexing (PTDM). SM packets are differentiated into two specified sub-QoS classes employing a novel buffer reservation technique and asynchronous buffer scheduling algorithm AIP3Q. We present a detailed analysis of the node throughput performance, demonstrating that buffering resource requirements are reduced in the optical packet switch, because processing and buffering of GST packets is avoided. The SM packet QoS differentiation permits a further reduction of buffer resources

3-Level Integrated Hybrid Optical Network (3LIHON) to Meet Future QoS Requirements

This paper presents a new hybrid network architecture including different transport technologies to support a wide range of services. In particular the proposed hybrid network provides three service levels, and a possible set of foreseeable services with different QoS needs is mapped into these levels to show the effectiveness of the hybrid networking in managing multi-service requests. In the switching nodes of the network, each service level is associated to a different switching technology, thus optimizing the switch implementation. In the nodes of the network, the service levels are distinguished based on optical encoding techniques, while an output collision stage manages the access to the output wavelengths. Performance studies show the effectiveness of the output collision mechanism.

Evaluation of QoS differentiation mechanisms in asynchronous bufferless optical packet-switched networks

Existing quality of service differentiation schemes for todays IP over point-to-point optical WDM networks take advantage of electronic RAM to implement traffic management algorithms in order to isolate the service classes. Since practical optical RAM is not available, these techniques are not suitable for a future all-optical network. Hence, new schemes are needed to support QoS differentiation in optical packet-switched (OPS) networks. In this article we first present an overview of existing QoS differentiation mechanisms suitable for asynchronous bufferless OPS. We then compare the performance of the presented schemes and qualitatively discuss implementation issues, in order to evaluate the mechanisms. In particular, we present an evaluation framework, which quantifies the throughput reduction observed when migrating from a best effort scenario to a service-differentiated scenario. Our study shows that preemption-based schemes have the best performance, but also the highest implementation complexity

Quality of Service in Asynchronous Bufferless Optical Packet Switched Networks

Optical Packet Switching (OPS) is a promising technology for future core networks due to the ability to handle bursty traffic, adaptability to changes in the network infrastructure and good network utilization. In order to provide sufficient Quality of Service (QoS) to the emerging range of real-time and critical business applications, service differentiation should be present in future OPS. This paper presents the Preemptive Drop Policy (PDP), which provides service differentiation in asynchronous bufferless OPS. Based on time-continuous Markov chains, we introduce an analytical model of the PDP for switches with and without wavelength conversion. We extend the PDP into the Adaptive PDP (APDP), which provides absolute QoS guarantees in OPS. Simulations performed validate our analytical model and show that the APDP operates properly in a dynamic changing system load scenario.

Quality of service in optical packet switched DWDM transport networks

For support of multimedia applications in Internet, at least four service classes are normally outlined. We expect optical packet switching to be of special interest in terabit capacity networks with a high number of wavelengths. Our analysis shows that when the wavelength dimension is used for contention resolution, and number of wavelengths is 32 or higher, node-delay is negligible. However buffering in optical packet switches is a scarce resource which use should be minimized. Based on the requirement of the future network, and on our packet switch performance analysis, we suggest reducing the number of service classes to two: A normal class (NCT) with medium low packet loss and a low need for buffering, and a high class (HCT) with a minimum of packet loss. Performance of a buffer reservation scheme is analyzed by simulation. Assuming the network of today with 10 % HCT traffic, assigning four buffer inputs to the HCT traffic, a difference in optical packet loss ratio of three orders of magnitude can be obtained. The same difference in optical packet loss ratio can be obtained if 50 % HCT traffic is assumed (network of tomorrow), by assigning a higher number of buffer inputs.

Effects of bursty traffic in service differentiated Optical Packet Switched networks

Service differentiation is a crucial issue in the next -generation Optical Packet Switched networks. In this paper we examine how bursty traffic influences the performance of a service differentiated Optical Packet Switched network. By using time -continuous Markov chains, we derive explicit results for the packet loss rates in the case of a bursty hyper-exponential arrival process. Results indicate that the performance is degraded as the burstiness of the arrival process increases.

Research in optical burst switching within the e-Photon/ONe network of excellence

This paper presents a summary of Optical Burst Switching (OBS) research within the VI framework program e-Photon/ONe network of excellence. The paper includes network aspects such as routing techniques, resilience and contention resolution, together with burst switch architectures. On the other hand, we also discuss traffic analysis issues, Quality of Service (QoS) schemes, TCP/IP over OBS and physical layer aspects for OBS.

QoS provisioning using traffic shaping and policing in 3rd-generation wireless networks

According to the recently presented QoS architecture by 3GPP, a traffic conditioner may be deployed to provide conformance of the negotiated QoS in UMTS. The traffic conditioning is performed by traffic shaping or/and policing. A framework of traffic conditioning with QoS provisioning in the 3G radio access network is proposed in this paper. The main idea of our traffic conditioning approach is to employ traffic shaping at each user equipment (UE) and traffic policing at the RNC. The traffic generated at each UE is regulated by a traffic shaper in the form of a token bucket, and the conformance of the traffic is policed at the RNC according to traffic policing policies. A system model based on the proposed framework is implemented. The simulation results regarding the impact of traffic shaping on packet discarding probability, the tradeoff between probability of non-compliance and shaping delay are also presented in this paper.

Scalability analysis of SDN-controlled optical ring MAN with hybrid traffic

The development of software defined networking (SDN) has instigated a growing number of experimental studies which demonstrate the flexibility in network control and management introduced by this technique. Optical networks add new challenges for network designers and operators to successfully dimension and deploy an SDN-based in the optical domain. At present, few performance evaluations and scalability studies that consider the high-bandwidth of the optical domain and the flow characterization from current Internet statistics have been developed. In this paper these parameters are taken as key inputs to study SDN scalability in the optical domain. As a relevant example an optical ring Metropolitan Area Network (MAN) is analyzed with circuit and packet traffic integrated at the wavelength level. The numerical results characterize the limitations in network dimensioning when considering an SDN controller implementation in the presence of different flow mixes. Employing flow aggregation and/or parallel distributed controllers is outlined as potential solution to achieve SDN network scalability.

Optical burst and packet switching: node and network design, contention resolution and quality of service

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.