Marek Michalski

The Routing Algorithm and Wide-Sense Nonblocking Conditions for Multiplane Baseline Switching Networks

A new control algorithm for the multiplane baseline switching network is proposed in this paper. This algorithm chooses a plane for a new connection in such a way that this new connection blocks the lowest number of possible future connections in the plane. We have proved, that when using this algorithm connections can be routed without blocking when the number of planes in the switching network is the same as in the rearrangeable one for even number of stages. When the switching network contains the odd number of stages, required number of planes is greater than in the rearrangeable switching network but less than in the strict-sense nonblocking one. Different implementations of the proposed algorithm are also considered. It should be noted, that the algorithm can determine the plane for a new connection in O(N0.5) time or even in O(1) time depending on the implementation. The overall time complexity of the proposed algorithm is from O(N3.5 log2 N) to O(N log2 N) depending on its implementation and number of processors used

A New Control Algorithm for Wide-Sense Nonblocking Multiplane Photonic Banyan-Type Switching Fabrics with Zero Crosstalk

A new control algorithm for log2(N, 0, p) switching networks composed of 2 x 2 switching elements has been proposed recently. Under this algorithm, log2(N,0,p) switching networks with even number of stages are wide-sense nonblocking (WSNB) if p is the same as for the rearrangeable nonblocking (RNB) one. The considerred algorithm and WSNB conditions did not take into account crosstalk constraint, which is an important factor in photonic switching. This paper enhanced this algorithm to the case when crosstalk in the switching fabric is not allowed. WSNB conditions for this enhanced algorithm are also derived. It is shown, that the number of planes required is less than those derived earlier in other papers for WSNB multiplane banyan- type switching fabrics under crosstalk constraint. Under this algorithm, log2( N,0,p) switching networks with odd number of stages and with zero crosstalk are WSNB if p is the same as for RNB one.

A Software and Hardware System for a Fully Functional Remote Access to Laboratory Networks

This paper presents a software and hardware system which enables users to have a full access to a laboratory network composed of switches, routers, and workstations. The physical topology of this network can be dynamically reconfigurable according to current requirements of a remote user or users. Users can reserve access to the system via a web site according to their profiles and rights granted by administrators. In order to configure a lab topology and its devices dedicated software is used.

The strict-sense nonblocking elastic optical switch

In this paper, we address the problem of the strict-sense nonblocking operation of an elastic optical switch. Elastic optical switches are used as nodes in elastic optical networks (EONs), where fine granular frequency slots or flexible grids are used in opposite to the traditional optical networks, where fixed grids are used. The switch architecture considered in this paper consists of waveband converting switches in input and output stages, while in the center stage there is only one wavelength selective space switch without wavelength conversion capabilities. We derive the number of frequency channels k needed in interstage links to ensure the nonblocking operation of the switch when input and output links have n frequency channels and a frequency slot of one connection is not greater than m frequency channels. Both, necessity and sufficient conditions are proved.

Rearranging algorithms for log 2 (N, 0, p) switching networks with even number of stages

In this paper we consider the rearrangeable multi-plane banyan-type switching fabrics, called also log2(N, 0, p) switching networks, with even number of stages. For such networks different rearranging algorithms have been proposed for both: one-at-a-time and simultaneous connection models. In this paper we consider the one-at-a-time connection model, where connections arrive to the system one-by-one, and in case of blocking rearrangements are realized. To our knowledge, known algorithms require several rearrangements, and the number of such rearrangements have not been considered in the literature. We propose the new rearranging algorithm for the multi-plane banyan-type switching fabric composed of even number of stages. This algorithm leads to success using only one rearrangement. We also introduce the modified version of this new algorithm, in which rearrangement of an existing connecting path can be realized without its interruption.

Wide-sense nonblocking log/sub 2/ (N, 0, p) switching networks with even number of stages

In this paper the new control algorithm for multi-log/sub 2/N switching networks is proposed. Wide-sense nonblocking conditions are derived and proved when this algorithm is used for connection set up in such kind of switching networks with even number of stages. It is shown, that under this algorithm and even the number of planes required for wide-sense non-blocking operation is the same as for the rearrangeable switching networks. To our knowledge this is the first switching network which achieves the same WSNB conditions as the rearrangeable one.

The Algorithm for Rearrangements in the Log2 (N, 0, p) Fabrics with an Odd Number of Stages

This paper presents a new way of representing the internal states of the log₂((N; 0; p) switching fabrics. Basing on this representation a new algorithm for rearrangements in such fabric was developed and is presented here. Also, the maximal number of rearrangements in the log₂((N; 0; p) switching fabrics with odd number of stages is presented.

The FPGA implementation of the Log 2 (N, 0, p) switching fabric control algorithm

This paper presents a hardware implementation of a control algorithm for the log2(N, 0, p) switching fabric. This algorithm controls both connections and disconnections in the strict sense of a nonblocking switching fabric. The hardware implementation of this algorithm in Virtex5 circuits is described. The presented implementation has been optimized in order to minimize the time response of the controller. The controller is suitable to work in applications which require very fast (even immediate) decisions. Simulations were performed and the hardware implementation shows that the controller is able to determine a plane for a new connection in one clock cycle. After this clock cycle the controller is also ready for the next connection.

Wide-Sense Nonblocking Multiplane Photonic Banyan-Type Switching Fabrics With Zero Crosstalk

A new control algorithm for log2(N, 0, p) switching networks composed of 2 x 2 switching elements has been proposed recently. Under this algorithm, log2(N,0,p) switching networks with even number of stages are wide-sense nonblocking (WSNB) if p is the same as for the rearrangeable nonblocking (RNB) one. The considerred algorithm and WSNB conditions did not take into account crosstalk constraint, which is an important factor in photonic switching. This paper enhanced this algorithm to the case when crosstalk in the switching fabric is not allowed. WSNB conditions for this enhanced algorithm are also derived. It is shown, that the number of planes required is less than those derived earlier in other papers for WSNB multiplane banyan- type switching fabrics under crosstalk constraint. Under this algorithm, log2( N,0,p) switching networks with odd number of stages and with zero crosstalk are WSNB if p is the same as for RNB one.

Strict-Sense Nonblocking W-S-W Node Architectures for Elastic Optical Networks

The paper considers optical node architectures for elastic optical networks. They use switching fabric topologies which are similar to the three-stage Clos switching networks. These architectures employ wavelength switching in the first and the third stages, and space switching in the second stage, and are also called W-S-W switching fabrics. In elastic optical networks, the optical spectrum is divided into frequency slot units. One frequency slot unit uses 12.5 GHz of bandwidth and an optical path may use m adjacent frequency slot units. Such connection is called an m-slot connection. For each architecture, strict-sense nonblocking conditions are derived and proved for such m-slot connections. The number of center stage switches and the number of frequency slot units in interstage links are calculated and evaluated. The considered architectures are compared to each other. When the maximum number of frequency slot units that may be used by one connection, is not too high, these architectures can be implemented in practice.