Wide-Sense Nonblocking Networks

A new method for constructing wide-sense nonblocking networks is presented. Application of this method yields (among other things) wide-sense nonblocking generalized connectors with n inputs and outputs and size O( n log n ), and with depth k and size O( n1 + 1/k ( log n )1 - 1/k )

Nonblocking Multirate Distribution Networks

This paper generalized known results for nonblocking distribution networks (also known as generalized connection networks) to the multirate environment, where different user connections share a switch\u27s internal data paths in arbitrary fractions of the total capacity. In particular, we derived conditions under which networks due to Ofman and Thompson, Pippenger, and Turner lead to multirate distribution networks. Our results include both rearrangeable multirate networks exceeds that of the corresponding space division network by a log log factor while the complexity of the wide sense nonblocking networks in within a factor of two the corresponding space division networks

Practical Wide-Sense Nonblocking Generalized Connectors

In this note, we show that wide-sense nonblocking networks can be obtained by cascading a pair of Cantor networks or a pair of Clos networks. The only constraint placed on the routing algorithms is that branching be restricted to the second network in the cascade. This result yields practical network for multipoint communication with complexities O(N(logN)2 and O(N1+1/r)

Crosstalk-free Conjugate Networks for Optical Multicast Switching

High-speed photonic switching networks can switch optical signals at the rate of several terabits per second. However, they suffer from an intrinsic crosstalk problem when two optical signals cross at the same switch element. To avoid crosstalk, active connections must be node-disjoint in the switching network. In this paper, we propose a sequence of decomposition and merge operations, called conjugate transformation, performed on each switch element to tackle this problem. The network resulting from this transformation is called conjugate network. By using the numbering-schemes of networks, we prove that if the route assignments in the original network are link-disjoint, their corresponding ones in the conjugate network would be node-disjoint. Thus, traditional nonblocking switching networks can be transformed into crosstalk-free optical switches in a routine manner. Furthermore, we show that crosstalk-free multicast switches can also be obtained from existing nonblocking multicast switches via the same conjugate transformation.Comment: 10 page

Study of wide-sense nonblocking switching networks from the approach of upper ideals.

by Kwok Siu Yu.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 48-49).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Background of switching networks --- p.1Chapter 1.2 --- Nonblocking properties of 3-stage networks --- p.5Chapter 1.3 --- Wide-sense nonblocking networks --- p.10Chapter 1.4 --- Routing algorithms by packing --- p.12Chapter 2 --- The Concept of the Upper Ideals --- p.15Chapter 3 --- "Routing algorithm over the network [6x10, 3x3, 10x6]" --- p.26Chapter 4 --- Simulation Program (SP) --- p.30Chapter 5 --- "Nonexistence of routing algorithm over the network [5x8, 3x3, 8x5]" --- p.35Chapter 6 --- Packing algorithms --- p.42Chapter 7 --- Summary and directions of further study --- p.4

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

A new scheme to realize crosstalk-free permutations in optical MINs with vertical stacking

©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Vertical stacking is an alternative for constructing nonblocking multistage interconnection networks (MINs). In this paper, we study the crosstalk-free permutation in rearrangeable, self-routing Banyan-type optical MINs built on vertical stacking and propose a new scheme for realizing permutations in this class of optical MINs crosstalk-free. The basic idea of the new scheme is to classify permutations into permutation classes such that all permutations in one class share the same crosstalk-free decomposition pattern. By running the Euler-Split based crosstalk-free decomposition only once for a permutation class and applying the obtained crosstalk-free decomposition pattern to all permutations in the class, crosstalk-free decomposition of permutations can be realized in a more efficient way. We show that the number of permutations in a permutation class is huge, enabling the average time complexity of the new scheme to realize a crosstalk-free permutation in an N by N network to be reduced to O(N) from previously O(NlogN).Xiaohong Jiang, Hong Shen, Md. Mamun-ur-Rashid Khandker, Susumu Horiguch

Blocking behaviors of crosstalk-free optical Banyan networks on vertical stacking

Banyan networks are attractive for constructing directional coupler (DC)-based optical switching networks for their small depth and self-routing capability. Crosstalk between optical signals passing through the same DC is an intrinsic drawback in DC-based optical networks. Vertical stacking of multiple copies of an optical banyan network is a novel scheme for building nonblocking (crosstalk-free) optical switching networks. The resulting network, namely vertically stacked optical banyan (VSOB) network, preserves all the properties of the banyan network, but increases the hardware cost significantly. Though much work has been done for determining the minimum number of stacked copies (planes) required for a nonblocking VSOB network, little is known on analyzing the blocking probabilities of VSOB networks that do not meet the nonblocking condition (i.e., with fewer stacked copies than required by the nonblocking condition). In this paper, we analyze the blocking probabilities of VSOB networks and develop their upper and lower bounds with respect to the number of planes in the networks. These bounds depict accurately the overall blocking behaviors of VSOB networks and agree with the conditions of strictly nonblocking and rearrangeably nonblocking VSOB networks respectively. Extensive simulation on a network simulator with both random routing and packing strategy has shown that the blocking probabilities of both strategies fall nicely within our bounds, and the blocking probability of packing strategy actually matches the lower bound. The proposed bounds are significant because they reveal the inherent relationships between blocking probability and network hardware cost in terms of the number of planes, and provide network developers a quantitative guidance to trade blocking probability for hardware cost. In particular, our bounds provide network designers an effective tool to estimate the minimum and maximum blocking probabilities of VSOB networks in which different routing strategies may be applied. An interesting conclusion drawn from our work that has practical applications is that the hardware cost of a VSOB network can be reduced dramatically if a predictable and almost negligible nonzero blocking probability is allowed.Xiaohong Jiang; Hong Shen; Khandker, Md.M.-ur-R.; Horiguchi, S