Jakob Buron

Label preference schemes in GMPLS controlled networks

The GMPLS assumption that all available labels are equal is reasonable in electronic networks but not always true in WDM optical networks where labels correspond to physical wavelengths. In this paper we present two schemes for collecting the preference for specific labels during GMPLS signaling. For this purpose a new use of the Suggested Label object is proposed, and a novel object called Suggested Vector is introduced. The approach is validated through simulations showing significant wavelength converter usage reduction in a WDM optical network

Wavelength-Converter Saving Span Restoration in GMPLS Controlled WDM Optical Networks

We present two label preference schemes to reduce wavelength-conversion during restoration path setup in GMPLS controlled optical networks exploiting span restoration. The amount of required wavelength-conversions can be reduced up to 34 percent.

Increasing Restorability for Local-to-Egress Restoration in GMPLS Controlled Networks with Limited Wavelength Conversion

We study the performance of the local-to-egress restoration method in GMPLS controlled optical networks, when a limited number of wavelength converters are available. We evaluate the recovery percentage for a converter-saving label assignment scheme and compare its performance to a simple scheme with and without releasing resources that are not used after the failure (stub release). Our simulations show that the converter-saving label assignment scheme without stub release outperforms the simple label assignment scheme with stub release, to the extent that stub release can be avoided without sacrificing restorability

Blocking Reduction of Span Restoration Requests in GMPLS Controlled WDM Optical Networks

The proposed label preference scheme reduces blocking of span restoration requests in GMPLS optical networks with limited wavelength conversion. By minimizing resource contention and conversion usage, it increases recovery percentage and reduces control plane load.

Bidirectional lightpath provisioning in GMPLS-controlled optical networks

This paper compares two GMPLS schemes for bidirectional lightpath provisioning. The novel scheme based on the label set, where both directions are set up with a backward reservation, is assessed against the standard scheme based on the upstream label, where the reverse path is established with a forward reservation unaware of wavelength availability. Results show that the label set scheme significantly outperforms the upstream label scheme, especially when detailed network status information is not advertised.

GMPLS-based packet contention resolution in connection-oriented OPS networks

Approaches for contention resolution among packets in the optical domain have been traditionally devised for distributed operation locally within individual nodes, exploiting both the time and wavelength dimensions. In this work, we focus on packet contention prevention in an optical packet-switched network, tackling the problem from the perspective of a network-wide end-to-end label-switched path (LSP) admission control and LSP-to-wavelength assignment. We present two contention-preventing wavelength assignment schemes, called minimum interference (MI) schemes, that can be implemented within a network control plane based on a generalized multiprotocol label switching (GMPLS) protocol suite. MI schemes envision that LSP-to-wavelength assignment is accomplished by a novel ranking policy utilized for the tie breaking of the GMPLS label set (i.e., the available wavelength set). Specifically, the novel GMPLS object named the suggested vector (SV) is populated during forward propagation of the path message, collecting, for each wavelength, the amount of bandwidth not interfering with already-established LSPs. During the backward propagation of the Resv message, the actual LSP-to-wavelength allocation is performed based on the preference level stored in the SV object. Numerical results show that MI schemes are effective in decreasing end-to-end packet loss and wavelength conversion probabilities, compared with the no-preference scheme that does not exploit such optimization.

Span Restoration in Optical Networks with Limited Wavelength Conversion

Next generation optical networks provide functionalities to dynamically provision and recover connections, while emerging technologies allow for the conversion between wavelengths. These devices are however expensive and hence it is likely that only few are deployed throughout the network. Accordingly, the unavailability of wavelength converters decreases the chance for successful connection establishment, especially in the recovery phase, where several restoration requests try to access a limited pool of resources. The recently proposed suggested vector scheme has been designed to perform converter-saving wavelength assignment in GMPLS networks. The converter saving property of the Suggested Vector is particularly desirable in span restoration, where the pre-failure path stubs have to be merged to the restoration path at the failure-adjacent nodes. In order to avoid wavelength conversion at the merging nodes, the wavelength of the connection stubs can be considered. In this study, we evaluate the recovery performance of the suggested vector scheme and a scheme exploiting standard protocol extensions only. The behavior of both schemes with a stub-aware extension for span restoration is also assessed. Our simulations show that the Suggested Vector scheme achieves a higher recovery performance than the standard scheme. Both schemes benefit from the stub-aware modification. The performance increase is especially predominant if few wavelength converters are available and at medium load ranges. Furthermore, we describe different scenarios to extend the suggested vector wavelength assignment scheme to multi-domain networks with focus on span restoration.

First experimental demonstration of a SOA/DFB-LD Feedback Scheme based all-optical flip-flop

Dynamic optical flip-flop operation is observed for the first time using a DFB laser diode connected with a SOA. Switching times of around 150 ps for switch pulse energies of around 6 pJ and a repetition rate of 500 MHz have been measured.

Demonstration of an All-Optical Class-of-Service Segregation Method for Edge Nodes in Hybrid Circuit/Packet Switched Networks

We demonstrate the principle of operation of an edge node for all-optical class-of-service segregation by the state of polarization. The operation is based on a combination of wavelength and polarization conversion using a standard wavelength converter.

Segmentation-based path switching mechanism for reduced data losses in OBS networks

The Optical Burst Switching (OBS) technology emerged as an alternative switching paradigm for the optical transport layer. Its biggest disadvantage (high data losses) has been the focus of numerous research papers. This paper proposes a data loss reduction technique, which relies on the combination of global network coordination between network nodes and local contention resolution. Via full-scale network simulation it is demonstrated that the proposed scheme has improved performance in terms of data losses and resource utilization, compared to its constituent mechanisms alone. Furthermore, the effectiveness of the mechanism has proven to be less sensitive to load variations in the medium and high load ranges. Additionally, its complexity and deployment cost are low, due to the absence of immature optical components in the network.