Architecture, design, and modeling of the OPSnet asynchronous optical packet switching node

An all-optical packet-switched network supporting multiple services represents a long-term goal for network operators and service providers alike. The EPSRC-funded OPSnet project partnership addresses this issue from device through to network architecture perspectives with the key objective of the design, development, and demonstration of a fully operational asynchronous optical packet switch (OPS) suitable for 100 Gb/s dense-wavelength-division multiplexing (DWDM) operation. The OPS is built around a novel buffer and control architecture that has been shown to be highly flexible and to offer the promise of fair and consistent packet delivery at high load conditions with full support for quality of service (QoS) based on differentiated services over generalized multiprotocol label switching

Scalable shared protection approach for mesh WDM-routed networks

The paper proposes an approach for calculating the protection pool size on each link in a mesh WDMrouted network. The protection pool evaluation is part of a shared protection scheme applied to a failure dependent scenario and based on aggregated information dissemination. Two models based on a probabilistic approach are proposed to provide a scheme that is scalable as the number of optical cross-connects (OXC), fibres and wavelength multiplexing in a core network increases. Precisely, two models based on a binomial and a beta-binomial distribution are presented. The evaluation of the models by simulation shows that both models are attractive propositions to offer protected ¸-services that do not require an absolute protection guarantee offered by (1:1) schemes or shared protection schemes requiring full network state information, or using partial information but with less efficient use of the fibre utilisation

Spare capacity modelling and its applications in survivable iP-over-optical networks

As the interest in IP-over-optical networks are becoming the preferred core network architecture, survivability has emerged as a major concern for network service providers; a result of the potentially huge traffic volumes that will be supported by optical infrastructure. Therefore, implementing recovery strategies is critical. In addition to the traditional recovery schemes based around protection and restoration mechanisms, pre-allocated restoration represents a potential candidate to effect and maintain network resilience under failure conditions. Preallocated restoration technique is particularly interesting because it provides a trade-off in terms of recovery performance and resources between protection and restoration schemes. In this paper, the pre-allocated restoration performance is investigated under single and dual-link failures considering a distributed GMPLSbased IP/WDM mesh network. Two load-based spare capacity optimisation methods are proposed in this paper; Local Spare Capacity Optimisation (LSCO) and Global Spare Capacity Optimisation (GSCO)

Performance analysis of a 2-D time-wavelength OCDMA wavelength-aware receiver with beat noise

The effect of beat noise on two-dimensional time-wavelength optical code-division multiple-access systems utilising wavelength-aware receivers is examined. A derivation of a general formula for the bit error probability taking into consideration multiple access interference (MAI) and other noise sources is given. In addition, a comparison between the system performance of such a receiver and the traditional configuration is presented. Studies to date that have focused only on the MAI limited case showed that the wavelength-aware configuration yields a better performance when compared to the traditional receiver. When beat noise is considered, the numerical results reveal that the performance of wavelength-aware receiver is very sensitive to beat noise and is not superior over the traditional receiver

A novel optical passive router ring architecture using MAGNet protocol

This paper introduces a family of bidirectional multi-fibre passive photonic ring architectures that may serve as a high-capacity network backbone for supporting next-generation data-centric services. We introduce a novel dual-router node design that avoids several non-ideal routing phenomena typically associated with passive networks based on cyclic graphs. Our design also achieves the requisite single-hop full-mesh connectivity needed for arbitrary node-to-node communications. A ring enlargement strategy is presented that allows this architecture to scale across a wide range of networking domains. A medium access protocol will also briefly elaborated

Designing a multi-hop regular virtual topology for ultrafast optical packet switching : node placement optimisation and/or dilation minimisation?

This paper studies the design of multi-hop regular virtual topologies to facilitate optical packet switching in networks with arbitrary physical topologies. The inputs to the virtual topology design problem are the physical topology, the traffic matrix and the regular topology. In this paper, this problem is tackled directly and also by decomposition into two sub-problems. The first sub-problem, dilation minimisation, uses only the physical topology and the virtual topology as optimisation inputs. The second sub-problem considers the traffic matrix and virtual topology as optimisation inputs. The solutions of these two sub-problems are compared with each other and against the results obtained when the global problem is optimised (using all three possible input parameters) for a variety of traffic scenarios. This gives insight into the key question of whether the physical topology or the traffic matrix is the more important parameter when designing a regular virtual topology for optical packet switching. Regardless of the approach taken the problem is intractable and hence heuristics must be used to find (near) optimal solutions in reasonable time. Five different optimisation heuristics, using different artificial intelligence techniques, are employed in this paper. The results obtained by the heuristics for the three alternative design approaches are compared under a variety of traffic scenarios. An important conclusion of this paper is that the traffic matrix plays a less significant role than is conventionally assumed, and only a marginal penalty is incurred by disregarding it in several of the traffic cases considered

Service level agreement framework for differentiated survivability in GMPLS-based IP-over-optical networks

In the next generation optical internet, GMPLS based IP-over-optical networks, ISPs will be required to support a wide variety of applications each having their own requirements. These requirements are contracted by means of the SLA. This paper describes a recovery framework that may be included in the SLA contract between ISP and customers in order to provide the required level of survivability. A key concern with such a recovery framework is how to present the different survivability alternatives including recovery techniques, failure scenario and layered integration into a transparent manner for customers. In this paper, two issues are investigated. First, the performance of the recovery framework when applying a proposed mapping procedure as an admission control mechanism in the edge router considering a smart-edge simple-core GMPLS-based IP/WDM network is considered. The second issue pertains to the performance of a pre-allocated restoration and its ability to provide protected connections under different failure scenarios

An optimum network selection solution for multihomed hosts using Hopfield Networks

This work introduces a Hopfield Neural Network approach to network selection for multihomed hosts which considers a range of relevant network parameters including available radio access technologies and traffic types (VoIP, video streaming, Web browsing and FTP-based). Also proposed is a novel utility function that further improves network selection. Results show that, in terms of QoS, the allocation obtained using proposed algorithm outperforms other two reference allocation schemes under a range of different scenarios

Performance modeling of an asynchronous optical packet switch for direct IP over WDM

The EPSRC project OPSnet addresses the design, modeling and implementation of an asynchronous optical packet switch (OPS) suited for 100Gb/s DWDM operation. This novel switch architecture allows direct IP transport over DWDM-based core networks. The paper reports on the system-level design and modeling of the core OPS module, with a focus on performance modeling aspects like simulation automation and results processing. The modeling results show that high throughput and low latency and very low packet loss can be achieved with this type of OPS

A novel design for an asynchronous optical packet switch

We present a novel design for an asynchronous optical packet switch. The architecture is GMPLS-compliant, DWDM-capable and fully scalable. The switch uses a novel in-line buffer design, based on parallel recirculating buffers. The buffers solve contention by statistical multiplexing, and can be configured to conserve packet order and prioritize traffic. The control system is based on a direct local lookup of the destination port and wavelength and traffic class using the packet label. Performance modeling indicates that the switch has excellent throughput with low latency and low packet los