Martin Nord

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

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.

Compact all-optical parity calculator based on a single all-active Mach Zehnder interferometer with all-SOA amplified feedback

An all-optical signal processing circuit capable of parity calculations is demonstrated using a single integrated all-active SOA-based MZI, exploiting the integrated SOAs for feedback amplification.

OpMiGua Hybrid Circuit- and Packet-Switched Test-Bed Demonstration and Performance

Hybrid optical network architectures that combine beneficial properties of circuit- and packet-switching are attractive for multimedia networks. We have already proposed and reported the experimental demonstration of elements of a hybrid optical network architecture, the OpMiGua network. We now report experimental characterization of a three-node OpMiGua network test-bed with ingress, core, and egress nodes. The experiment confirms zero packet loss and jitter of the circuit-switched guaranteed service transport class of service (CoS) and shows how adding a packet-switched statistical multiplexed CoS increases lightpath utilization

Experimental Demonstration of OpMiGua Hybrid Circuit/Packet Nodes

Separation of two QoS classes in a hybrid time-interleaved circuit/packet node is demonstrated. Guaranteed packets follow circuit switched paths with absolute priority, while statistical multiplexed packets are packet switched and are subject to packet loss.

Node design in optical packet and optical burst switching

The paper discusses recent progress in optical packet switching (OPS) and optical burst switching (OBS). Main factors influencing node design are considered, before focusing on wavelength router designs for OPS. Performance and complexity of OPS and OBS node designs are compared, with the aim of identifying prerequisites for, and viable paths towards, statistically multiplexed optical networks.

Transparent optical protection switching scheme based on detection of polarisation fluctuations

We have demonstrated a novel transparent optical protection-switching scheme capable of switching with minimum, and even without, loss of data. The detection circuit has proven to trigger the optical switch when failure situations, like the unplugging of a fibre-connector or the fibre being exposed to abnormal environmental conditions, occurs. We believe this protection scheme will be attractive for networks where optical transparency or high level of protection security, like protection against security attacks, tampering or earthquakes, are desired.

Hybrid wavelength routed and optical packet switched ring networks for the metropolitan area network

Increased data traffic in the metropolitan area network calls for new network architectures. This paper evaluates optical ring architectures based on optical packet switching, wavelength routing, and hybrid combinations of the two concepts. The evaluation includes overall throughput and fairness aspects in both uniform and unbalanced traffic scenarios, for both Poisson and bursty input traffic. Simulations show a trade-off between performance and complexity. Whilst the static wavelength routed optical network is a good solutions for uniform traffic, the proposed hybrid architectures are more attractive when traffic is unbalanced.

Impact of four-wave-mixing in polarisation multiplexed 12.5 GHz channel spacing WDM systems

The impact of four-wave-mixing (FWM) induced crosstalk in medium haul WDM systems with 12.5 GHz channel spacing is investigated. Adjacent channel polarisation and channel powers are varied. By using an orthogonal polarisation scheme, FWM efficiency is significantly reduced. Differential Group Delay (DGD) has no significant impact on FWM efficiency in the investigated polarisation multiplexed system.

Optical switching technologies for fast optical packet switching

A survey of optical switching technologies being candidates for an optical packet switched (OPS) network is presented. Switching time range for optical switching fabrics is found through analysis. In light of this, and based on reported switch devices, switching technologies are identified as candidates for OPS. Their suitability from a network perspective is then discussed.