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Elastic Optical Network (EON) has emerged as a solution to manage different kinds of services, improving network scalability and efficiency. However, EONs tend to present differences in service performance due to the uneven bandwidth requirements. In addition, uneven network performance among routes with different hop counts is a known issue, affecting not only optical networks or EONs, but also computer networks. We call this problem inter-routes unfairness. In this letter we propose strategies based on the trunk reservation technique to solve it. Our results show that it is possible to deal with the inter-routes unfairness problem. We believe that this kind of strategy opens opportunities to be applied for connections traveling longer and more loaded routes, that would lead to a minimum impact in the overall network performance.

This paper deals with the problem of service differentiation in an optical packet-switched backbone. A QoS-aware network function based on different routing and contention resolution strategies for different classes of service is proposed and analyzed. Contention resolution is performed by using both wavelength and time domains and QoS differentiation at the single node level is achieved by resource partitioning in the wavelength domain. This technique is combined with multi-path routing at the network level. The paper, analyzing different network topologies under different traffic assumptions, shows that the proposed strategies guarantee a good performance differentiation between two levels of traffic priority. Finally, a network design procedure is also illustrated and discussed.

We address the problem of congestion resolution in optical packet switching (OPS). We consider a fairly generic all-optical packet switch architecture with a feedback optical buffer constituted of fiber delay lines (FDL). Two alternatives of switching granularity are addressed for a switch operating in a slotted transfer mode: switching at the slot level (i.e., fixed length packets of a single slot) or at the burst level (variable length packets that are integer multiples of the slot length). For both cases, we show that in spite of the limited queuing resources, acceptable performance in terms of packet loss can be achieved for reasonable hardware resources with an appropriate design of the time/wavelength scheduling algorithms. Depending on the switching units (slots or bursts), an adapted scheduling algorithm needs to be deployed to exploit the bandwidth and buffer resources most efficiently.

This paper addresses the problem of congestion resolution and quality of service differentiation in optical packet switching. The paper shows that by designing congestion resolution algorithms that combine the use of the wavelength and the time domain it is possible to significantly reduce information loss phenomena and also to guarantee quality of service differentiation among traffic classes. In particular this is achieved by means of QoS algorithms specifically designed to exploit the characteristics of optical technology. The results are different from the QoS techniques typically implemented in electronic networks. Performance evaluation obtained by simulation shows the influence of the main system parameters on packet loss probability and delay for two service classes.

This paper addresses the problem of building optical packet switches that are able to effectively cope with variable length packet traffic and quality of service management, therefore able to support IP traffic. The paper aims at showing that the availability of dense wavelength division multiplexing is crucial. By suitably exploiting the wavelength dimension a multistage fiber delay line buffer can be implemented, with fine granularity and long delay with an architecture of limited complexity. This is necessary to fulfill the buffering requirements of variable length packets. Furthermore, the wavelength domain is proved to be more effective than the time domain to manage different levels of quality of service. Algorithms are presented that are peculiarly designed for this environment showing that they can effectively differentiate the packet loss probability between three priority classes.

This paper deals with the calling procedures of the novel service-oriented networking architecture called Hybrid SIP Network (H-SIP). H-SIP by exploiting the Session Initiation Protocol (SIP), is able to support a population of users moving within a network of trusted domains over wireless and/or wired connections. The proposed architecture combines the flexibility of a peer-to-peer connectivity network with the efficient signaling organization of a hierarchy of domains.

The rapid increase of Internet traffic is pushing the deployment of WDM technology in the next-generation high-speed Internet backbone. Routers in the backbone could still be the potential bottleneck. In this article we consider some design issues of high-throughput optical routers which combine the advantages of WDM with the new optical switching technology. We first introduce a proposed Internet architecture based on the optical burst switching mechanism. Some important design issues in optical buffering and control function are addressed which are expected to have significant effects on router performance. Numerical results of a simulation study are also presented along with discussions.

This article presents a new proposal for TCP-IP backbone implementation based on optical packet switching technology. The proposed network architecture merges the flexibility in resource management of packet switching with the high capacity offered by full optical technology.

A new photonic packet switch based on wavelength encoding of information and on the broadcast-and-select principle for routing is presented. A suitable management of a set of fiber delay lines to allow all-optical output queuing is performed through electronic control. Implementation and traffic aspects are analyzed. Experimental results are given to demonstrate the feasibility of the switch and its future evolution, achieved by a rack-mounted subequipped demonstrator. Different design options are discussed in order to achieve a global terabit per second capacity. Performance is evaluated by simulation under the typical traffic conditions that arise in the broadband communication environment.

This paper presents an analytical model to evaluate the performance of an optical wavelength-routed network for inter- and intra-data center interconnection, designed to work according to the cloud computing paradigm. Such a scenario calls for anycast routing of service requests to find a network path that best suits both connectivity and IT resource requirements. The analytical model is based on conventional queuing theory for loss systems combined with an ad-hoc combinatorial analysis of the anycast service alternatives. The model presented here is meant to provide engineering guidelines for data center interconnection networks supporting the cloud paradigm, in particular in terms of performance and cost of resource distribution.

This paper investigates the kind and quantity of wavelength converters required for an effective packet contention resolution scheme. Tunable and non tunable wavelength converters are considered showing that optimal performance can be achieved with both. Then the utilization of such wavelength converters is evaluated showing that, by switching them off when not used, a significant saving in power consumption can be achieved.

This paper presents PI-OPS (Parallel-Iterative Optical Packet Scheduler) a parallel-iterative scheduler for asynchronous Optical Packet Switching nodes with optical buffering. Optical packets are assembled by aggregating IP packets, and attaching an optical packet header. Conventional schemes process optical packet headers one by one, in a sequential form. Then, the worst case algorithm response time is tightly coupled to switch size. In contrast, in PI-OPS all the optical packets received during a given time window are jointly processed to optimize the delay and output wavelength allocation, applying void filling techniques. The scheduler has a deterministic response time, independent of the traffic arrival's pattern. In addition, PI-OPS has been specifically designed to allow a parallel electronic implementation similar to the ones found in VOQ schedulers. In this respect, we evaluate the traffic loss performance of the scheduler in different settings, to dimension a set of hardware related parameters. Finally, we conduct an emulation of an FPGA implementation of a large-scale version of the scheduler. Results support the feasibility of its implementation.

In this letter we consider burst switching for very high speed routing in the next generation Internet backbone. In this scenario, Internet protocol (IP) packets to a given destination are collected in bursts at the network edges. We propose a burst assembly mechanism that can reduce the traffic autocorrelation or degree of self-similarity, and at the same time keep the delay due to burst formation limited at the network edges.

Generalized Multi-Protocol Label Switching (GMPLS) has recently become the reference signalling scheme for optical networks. This paper focuses on the idea of using GMPLS as a resource allocation scheme in an Optical Packet-Switched (OPS) network scenario. In particular, dynamic wavelength allocation to different traffic flows is discussed and an integer linear programming formulation of this problem is introduced, aiming at reducing the chance of contention events on the output channels by grouping the flows incoming on the same input wavelength and destined to the same output fiber and allocating them to the same output wavelength. Keywords: optical networks, optical packet switching, GMPLS, wavelength allocation.

This paper proposes a methodology to compare scheduling algorithms for congestion resolution in optical burst switching or optical packet switching networks, focusing on the issue of wavelength conversion capabilities. The performance of such algorithms when full wavelength conversion is available at the switching nodes are compared with the case of conversion capabilities over a limited range of wavelengths. The results presented show that limited range wavelength conversion is not necessarily performing worse than full wavelength conversion, as long as the correct terms of comparison are considered.

This paper compares scheduling algorithms for congestion resolution in optical burst and/or packet switching networks, focusing on the effectiveness of wavelength and time multiplexing. The aim is to show whether it may be more convenient to invest in wavelength conversion or in some form of buffering when designing all optical switching elements.

Performance evaluation of congestion resolution schemes in OPS networks has been mainly limited to packet loss probability and/or queuing delay. In this paper we aim at broadening the scope of this evaluation by considering also out-of-sequence delivery and delay jitter, providing a framework to quantitatively measure the different effects that congestion resolution algorithms have on the packet stream.

This paper considers the problem of service differentiation in an optical packet switched backbone. We propose and analyze a QoS routing approach based on different routing and congestion management strategies for different classes of service. Congestion resolution is achieved by using the wavelength and time domain and QoS differentiation in the single node is achieved by resource reservation in the wavelength domain. This is combined with alternate routing at the network level. In the paper we show that the proposed strategy guarantees very good performance to the high priority traffic with very limited impact on low priority traffic.

The new telecommunication networks scenario is characterised by a very rapid increase of the volume of traffic, and also very variable and unpredictable traffic demands. In this context, all-optical packet switching is emerging as the most promising technology for covering such new requirements. In this paper, we deal with the performance analysis of an optical packet switch with a feedback delay line buffer configuration. The network mode operation is slotted and the case of a realistic traffic model (i.e., variable-length packets modelled by self-similar traffic) fitted into trains of fixed-size slots is considered. Results from contention resolution performed by using both the time and the wavelength domains show that they must be exploited as combined tools in order to obtain good node performance.

An ATM multiplexer with different classes of bursty sources is considered for evaluation of the effects of bursty traffic variations on its performance. A discrete-time Markov chain model is developed to obtain cell loss probability both for the whole set of sources and for each class. Calculations carried out for the particular case of two classes, with a first class behaving as declared at call set up and a second class violating that reference situation by variation of some of the bursty traffic parameters. The results show that the most dangerous violation is represented by burst length increase, which will play a key role for the definition of congestion avoidance strategies. >

This paper deals with an MPLS over DWDM network scenario and with the related problem of Label Switched Path (LSP) allocation in wavelengths. Static and dynamic allocation strategies within an optical packet switch are considered and compared. In particular dynamic allocation algorithms can be used to improve the overall system performance by exploiting queuing behaviors related to the connection-oriented nature of the traffic. As a consequence packet loss probability is obtained in an acceptable range with very limited queuing resources as required by implementation limits.

This paper addresses the problem of quality of service management in optical packet switching over DWDM. Asynchronous, variable length packets are considered and algorithms able to offer congestion resolution and quality of service differentiation are presented, with reference to both connectionless and connection oriented network scenarios. The paper aims at showing that it is possible to guarantee differentiation of the quality of service among traffic classes, with very little buffering requirements.

In this paper a semi-analytical procedure is employed to evaluate the performance of a wireless ATM local area network based on the IEEE 802.11 MAC protocol, taking into account the effects of propagation over a real radio channel. Numerical results are presented as a function of the MAC frame length and of the signal-to-noise ratio in order to evaluate network performance and to provide guidelines for the overall system design.

This paper deals with the problem of an MPLS packet switched network with DWDM links and addresses the issue of congestion avoidance by means of wavelength sharing among MPLS connections. The paper proposes an algorithm for wavelength sharing that aims at minimizing congestion and limit queuing requirements.

This paper deals with the problem of connection to wavelength assignment in an MPLS optical packet switched network with DWDM links. The need to adopt dynamic allocation of connections to wavelengths is outlined to avoid congestion and dynamic wavelength assignment algorithms are proposed. The main results show the effectiveness of dynamic assignment with respect to static one and show that the connection configuration can be exploited for performance enhancement

This paper deals with the problem of simulating an optical packet switch for IP traffic (asynchronous variable length packets) relying on wavelength encoding for routing and on delay lines for buffering. A simulation model of this switching architecture based on the use of the Petri Nets formalism is presented, and its implementation by means of the Artifex simulation tool described.

This paper addresses the problem of building optical packet switches able to effectively cope with variable length packet traffic, such as IP traffic. Aswit ching architecture equipped with a multistage fiber delay lines based buffer is presented. The aim is to realize a buffer with fine granularity and long delay with an architecture of limited complexity. QoS mechanisms are proposed to support service differentiation by exploiting the wavelength resource and are evaluated by simulation.

This paper addresses the problem of building optical packet switches able to effectively cope with variable length packet traffic, such as IP traffic. A switching architecture equipped with a multistage fiber delay lines based buffer is presented. The aim is to realize a buffer with fine granularity and long delay with an architecture of limited complexity.

In this paper a network architecture for all optical packet switching is presented, suitable for both long distance and metropolitan application. Overall network architecture, protocol layering, functional sub-blocks required and wavelength management are discussed with reference to the latest results obtained within the ACTS Project KEOPS (Keys in Optical Packet Switching).

This paper present the definition of a new transfer mode suited for all optical packet switching. A preliminary format of the optical packet has been defined, consisting of a header at fix bit rate and a payload, switched transparently inside the network, able to carry whatever service and bit rare. This optical packet is inserted in a time slot of fixed time length, regardless of the link speed, in order to siriplify switches operation and guaranty the network modularity. In this paper the issue of the optimal size of the tine slot is addressed, with reference to access delay and traffic shaping.

The application of the IEEE 802.11 access protocol for wireless local area networks (WLAN) to an ATM wireless environment is considered with the aim to support ATM virtual connections. Two different schemes are considered to perform cell multiplexing in MAC frames. The proposed solutions are suitably discussed and evaluated by means of simulation in a multiservice environment with data and video traffic. The effect of the presence of fading in the communication channel is also taken into account.

This paper addresses the design of an optical packet switch able to effectively cope with variable length packet traffic, such as IP traffic. A switching architecture equipped with a multistage fiber delay line buffer is presented, that is able to realize fine time granularity and long delay. WDM is introduced to solve switch internal blocking and to enhance buffer exploitation. Packet loss performance, evaluated by simulation, is discussed in relation to the degrees of freedom available for switch design, to show the feasibility of a switch for the IP environment.

Third generation cellular systems will have to accommodate a variety of different services and very high traffic volumes. Hence, flexible and efficient multiple access protocols are sought. We analyse the performance of the packet reservation multiple access (PRMA) protocol, in the case of mixed voice and data traffic. In particular we consider the impact on the performance of voice traffic of the added data traffic, in a variety of different configurations. The aim is to understand the effect of the various parameters, that is the delay, dropping probability, and burstiness, on the overall performance. Finally, the effect of a data traffic shaping is taken into account in order to achieve better system performance.

Out of order delivery and/or delay jitter are typical phenomena occurring in networks adopting a packet transfer mode and may have a relevant impact on the behavior of higher layer protocols. In this paper an original framework is proposed to analyze these phenomena in optical packet-switched networks that employ the wavelength and the time dimensions to solve congestion. This framework is the first step toward a deeper understanding of the interaction between transport networks and higher layers behaviors.

The performance of the IEEE 802.11 protocol for wireless local area networks (WLAN), is analysed when applied to the case of a wideband WLAN carrying high bit rate multimedia services (such as voice, video and high speed data) that should be interconnected with a wired, ATM based, broadband network. The paper evaluates the protocol in this more advanced environment that is supposed to be the trend of local area networking in the medium term future. As far as the interface with ATM is considered, the use of cell clustering in longer radio packets is also proposed and discussed, showing that it can significantly improve the protocol performance. Overall the results obtained are very encouraging suggesting that the protocol may be considered as a starting point for the development of a wireless wideband LAN.