Journal of Telecommunications and Information Technology, 2018, nr 1

In most cases defragmentation occurs, in elastic optical networks, in the links between the network’s nodes. In this article, defragmentation in an elastic optical network’s node is investigated. The W-S-W switching architecture has been used as a node. A short description of a purpose-built simulator is introduced. Several methods of defragmentation which are implemented in this simulator are described as well

The Strict-Sense Nonblocking Multirate l

This paper considers the nonblocking conditions for a multirate logd(N,0,p) switching network at the connection level. The necessary and sufficient conditions for the discrete bandwidth model, as well as sufficient and, in particular cases, also necessary conditions for the continuous bandwidth model, were given. The results given for dn-1/2f0≥f1+1 in the discrete bandwidth model are the same as those proposed by Hwang et al. (2005); however, in this paper, these results were extended to other values of f0, f1, and d. In the continuous bandwidth model for B+b>1, the results given in this paper are also the same as those by Hwang et al. (2005); however, for B+b≤1, it was proved that a smaller number of vertically stacked logdN switching networks are needed

Combinatorial Properties and Defragmentation Algorithms in WSW1 Switching Fabrics

A spectrum defragmentation problem in elastic optical networks was considered under the assumption that all connections can be realized in switching nodes. But this assumption is true only when the switching fabric has appropriate combinatorial properties. In this paper, we consider a defragmentation problem in one architecture of wavelength-space-wavelength switching fabrics. First, we discuss the requirements for this switching fabric, below which defragmentation does not always end with success. Then, we propose defragmentationalgorithms and evaluate them by simulation. The results show that proposed algorithms can increase the number of connections realized in the switching fabric and reduce the loss probability

Journal of Telecommunications and Information Technology, 2018, nr 1

The rearreangeable conditions for the 2×2 three-stage switching fabric of a W-S-W architecture for elastic optical switches are considered in this paper. Analogies between the switching fabric considered and the three-stage Clos network are shown. On the other hand, differences are also shown, which presented the modifications required in the control algorithm used in rearrangeable networks. The rearrangeable conditions and the control algorithm are presented and proved. Operation of the proposed control algorithm is shown based on a few examples. The required number of frequency slot units in interstage links of rearrangeable switching fabrics is much lower than in the strict-sense non-blocking switching fabrics characterized by the same parameters

The Optical Signal-to-Crosstalk Ratio for the MBA(<i>N</i>, <i>e</i>, <i>g</i>) Switching Fabric <xref rid="fn-sensors-977327" ref-type="fn">†</xref>

The banyan-type switching networks, well known in switching theory and called the logdN switching fabrics, are composed of symmetrical switching elements of size d×d. In turn, the modified baseline architecture, called the MBA(N,e,g), is only partially built from symmetrical optical switching elements, and it is constructed mostly from asymmetrical optical switching elements. Recently, it was shown that the MBA(N,e,g) structure requires a lower number of passive as well as active optical elements than the banyan-type switching fabric of the same capacity and functionality, which makes it an attractive solution. However, the optical signal-to-crosstalk ratio for the MBA(N,e,g) was not investigated before. Therefore, in this paper, the optical signal-to-crosstalk ratio in the MBA(N,e,g) was determined. Such crosstalk influences the output signal’s quality. Thus, if such crosstalk is lower, the signal quality is better. The switching fabric proposed in the author’s previous work has lower optical signal losses than a typical Beneš and banyan-type switching networks of this same capacity and functionality, which gives better quality of transmitted optical signals at the switching node’s output. The investigated MBA(N,e,g) architecture also contains one stage fewer than banyan-type network of the same capacity, which is an essential feature from the optical switching point of view

Strict-Sense Nonblocking Conditions for the log2⁡N-1 Multirate Switching Fabric for the Discrete Bandwidth Model

The article discusses the strict-sense nonblocking conditions derived for the log2⁡N-1 multirate switching fabric for the discrete bandwidth model at the connection level. Architecture of the log2⁡N-1 switching fabric was described in previous study; however, conditions for the multirate discrete bandwidth model as well as comparison with different structures have not been published before. Both sufficient and necessary conditions were introduced and proved in this study. A few numerical examples which help to understand an idea of the multirate bandwidth model for the log2⁡N-1 switching fabrics were delivered as well. Additionally a comparison of achieved results to the banyan switching structures and a comparison of the costs of all mentioned in this study structures expressed as the number of optical elements were done

HARDWARE ABSTRACTION LAYER FOR NON-OPENFLOW CAPABLE DEVICES

This paper describes a viable and experimentally-tested way forward for augmenting legacy network elements with software-defined networking control. Following and implementation-driven approach we have explored the possibilities for adding SDN-based interfaces to devices which are not compatible with OpenFlow. OpenFlow is arguably a leading control-place protocol for the upcoming generation of operator networks. Yet not all domains will be equipped from the very beginning with compatible supporting frameworks. To address this gap, we introduce the Hardware Abstraction Layer (HAL) for non-OpenFlow capable devices which tackles this problem. We discuss the advantages of the proposed approach and explain how a HAL-based architecture can support different classes of network devices

Hardware Abstraction Layer for non-OpenFlow capable devices

This paper describes a viable and experimentally-tested way forward for augmenting legacy network elements with software-defined networking control. Following and implementation-driven approach we have explored the possibilities for adding SDN-based interfaces to devices which are not compatible with OpenFlow. OpenFlow is arguably a leading control-place protocol for the upcoming generation of operator networks. Yet not all domains will be equipped from the very beginning with compatible supporting frameworks. To address this gap, we introduce the Hardware Abstraction Layer (HAL) for non-OpenFlow capable devices which tackles this problem. We discuss the advantages of the proposed approach and explain how a HAL-based architecture can support different classes of network devices